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- Опубліковано 19 січ 2022
- I wanted a simple BT transmitter for my ESP32 Web Radio so I tested this one out.
► JLCPCB Only $2 for PCB Prototype any colour jlcpcb.com/cyt
You can either use this as-is, or connect it up to the serial pins of your Arduino to manage it. Very simple with excellent sound quality.
HARDWARE
Bluetooth Audio Transmitter Module Board 4.1 Stereo Audio GFSK Transceiver Wireless Speaker Headphones KCX_BT_EMITTER 5V
NB: change the delivery country to yours (at the top of the screen)
s.click.aliexpress.com/e/_9iRqhc
Typical small 2.4GHz antenna with lead and tiny plug suitable for this board:
s.click.aliexpress.com/e/_9JXN6r
Anker Bluetooth Speaker I used in the demo, small but sounds OK.
Can play from SD card, AUX in, FM Radio and Bluetooth.
amzn.to/320sH9Q
DOCUMENTATION
► Utilities to help program the KCX_BT_EMITTER by Mark-MD047
github.com/Mark-MDO47/Bluetoo...
► Electro-Tech-Online (aka Dr G) with details of AT commands (and more) for the KCX_BT_EMITTER
www.electro-tech-online.com/t...
► Partly translated documentation for AT commands
www.electro-tech-online.com/a...
► AT Command List for ESP (Espressif)
docs.espressif.com/projects/e...
► List of all my videos
(Special thanks to Michael Kurt Vogel for compiling this)
bit.ly/UA-camVideoList-RalphB...
If you like this video please give it a thumbs up, share it and if you're not already subscribed please consider doing so and joining me on my Arduinite (and other μControllers) journey
My channel, GitHub and blog are here:
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• / ralphbacon
• ralphbacon.blog
• github.com/RalphBacon
• buymeacoffee.com/ralphbacon
------------------------------------------------------------------ - Наука та технологія
PCB breakout boards ALL GONE! Sorry, everyone. If you have already emailed me your address you should get one in about 1 week.
The Gerber files are in my GitHub for you to download and send to the PCB manufacturer of choice (JCLPCB.com made mine).
github.com/RalphBacon/235_KCX_BT_EMITTER-Breakout-Board
NOTE: if you include a comment here *with a link to another site* YT will zap your comment. Nowt to do with me, honest. 😂
How do I download the Gerber files?
Even though this is somewhat of a "niche" topic (as you put it), I , and I'm sure many of your subscribers, appreciate the effort it took and the expertise you have passed on to each of us.
A big "Thank you!"
I appreciate that! Funnily enough, niche it might be, but all 16 PCBs were claimed! I never would have thought that, so maybe not quite so 'off piste' as I feared! 😀
Thank you Hayes Modems for the AT command set. My office was next door to them in Westlake Village, CA.
Well, l love it or hate it, the fact it's still being used today must mean it was a good invention!
I love your videos. I just found your channel and I'm catching up on all your material. Thanks.
Glad you like them! You will be busy watching all 235 videos!
Great to hear from you again, unless UA-cam hasn't been sending notifications again. Either way hi Ralph. I've been getting into gardening mostly of late. I haven't done any electronics in quite some time. However, now you're like a different cousin I've never met. I hope 2022 is a great year for you. I didn't see the link in the comments, but I'll look in the description before I go. Take care and keep healthy.
OMG where have you been hiding, Steven? I thought winter time was when electronics projects got made, all those dark evenings? Anyway, great to see you back here, dive right in!
Not tried bluetooth with any of my gadgets so far. I might have a play after watching this. Thanks Ralph
You should! Cheap to play about with!
Thank you for the breakout board it looks great I am waiting for the delivery of KCX_BT_EMITTER as I am eager to build on your board again thank you so much for the board.
Hope you enjoy it! Do read the comment in my GitHub for this video about the external antenna!
Another great video, thanks Ralph
Glad you liked it!
Thanks for the demo and information. It always seems more difficult to find Bluetooth transmitters than receivers, and I've often used those little transmitters with a built in battery, but found it a bit messy; these little boards look like they should work a treat.
Glad it was helpful! And so far, they do indeed work a treat!
Whoa this would be cool to use to make a hands-free system for a car 🤘🏽🔥
The sky's the limit for sure!
Enjoyed it, learned, liked and commented. :)
Glad you enjoyed it, Ronald!
Thanks Ralph, the breakout boards are invaluable i've used both that I have 1 for ESP32 web radio and one to add BT to my sonos connect! Thanks again, I wish i'd have had this video when i first started playing because the not sending CR or LF to the device when sending AT commands drove me mad! you just get "command error" back from the device, so you think it is the command thats wrong not the fact you are sending a LF!!! Happy days, Keep the videos coming :-)
Dave
P.S. Not had any issues with the antenna and the breakout board, however a cheap external BT antenna does extend the range quite significantly!
I'm sorry I didn't mention the line ending bit to you earlier, Dave, my bad 😳but at least you got it working now!
Regarding the external transmitter (one of which I have, but not tried) did you have remove any components (eg a null resistor) on the board to use it?
@@RalphBacon As far as i can see the micro connector and on board antenna are connected in parallel, i have not modified the board at all and range is far better when the external is connected.
I'll give it a go later, thanks for letting me know, Dave.
I've given it a go using a small rotatable antenna that I bought a long time ago for an ESP32 but never used. FANTASTIC range and quality difference! I will be updating my GitHub with details so others can benefit from your experience Dave, thank you so much for nudging me into trying this. 👍
Welcome BACK to you too Mr. Bacon :)
😜 Well, at least you know whose video this is! Good to hear from you Christian.
Great video. Thanks.
You are welcome!
Putting one inside a Ipod and need this module because it has an antenna connection. It is tough to solder but ill get it. I needed the wire specs and your video had what i needed. Thanks
Great! I wish you every success with your soldering (and project).
THANK YOU Sir.. تشکر از بابت آموزش بسیار عالی
You are most welcome!
Very interesting that the old Hayes modem AT command format is still being used 40+ years later.
Always a good standby, it would seem. Also the BT modules HC-05 and HC-06 so the same. Perhaps it's a BT thing?
I believe you need to use an isolated power supply with these modules. I remember attempting to power it from my laptop's USB port and provide it with the signal from my laptop's aux output and I got a horrific amount of noise; however, when powering from a li-ion cell, it was absolutely fine. In theory, using one of those potted isolated modules for a few pounds from eBay or similar would likely suffice for this. In practice of course, I haven't tried that yet
I think that's true for anything _audio_ plugged into a non-battery USB power source.
For instance, all these sound horrendous when plugged into my TV's USB port:
o Amazon TV Stick
o KCX_BT_EMITTER
o Every other BT transmitter I've tried
o Small USB-powered Audio Amplifier
They all work OK when plugged into quality wall-warts but are horrible if plugged into a PC/laptop USB port or my TV's USB port.
I'm doing a project right now to add a 'filter' of some sort to that very port so I can run my Amazon TV Stick from it without it sounding like someone frying sausages (should that be Bacon?) in the not-so-background!
Thank you mr. 😊
You're very welcome!
Until recently those devices BT transmitters where not available for cheap. Finally we got some .
Yes, that's why I dived in here, value for money.
Hi Ralph.
Looks like a very interesting module and has come at the perfect time for me. Thanks.
I'm looking to build an audio switch for a stack stereo system to allow for multiple inputs and outputs. As well as RCA, I planned to add bluetooth.
So I'm very interested in getting my mitts on one of your breakout boards. Please advise how to do this please.
( I'm UK based)
Thanks.
Just send me an email, Jason, with your address. You'll find my email address on this page: ua-cam.com/users/RalphBaconabout It's hidden so I don't get (even more) spam!
Works like a charm. Good sound, no noise. Only using 5 of those pins so used that SOT 20 1.2->2.5 cm adapter. Connects every time so don't need the led, connect, or tx,rx pins. Only catch, mine doesn't work at 3.3V with my ESP32 3.3V pin. But only pin connected to it is Vin(5V). The 3 audio pins are connected to the audio out pins of the PCM5102 i2s chip. BT speaker is a Sanyun SW010.
Great, very happy you got it working.
@@RalphBacon One more little catch. The co-habitation of the wifi and bluetooth in a small enclosure is difficult. Without the bluetooth turned on, I have a wifi range>10 meters in my house. When booth are running it's about 2 meters. Is there a way to turn down the KCX transmit level instead of placing my wifi repeater next to my enclosure? Thanks!
I do believe that there is a "transmit power" variable on the BT the same as there is on the Wi-Fi (which you might want to boost to the highest value).
@@RalphBacon Thanx your answer. Actually, the BT range is >10m. It's the low Wifi range (2m) that's bugging me. Have to either:
1. Increase the Wifi Tx xmit pwr. (n/chng)
2.DECREASE the BT Txmit pwr. (not found).
I'll just keep the Wifi repeater close to my ESP32.
Or swap the ESP32 for one that allows an external antenna (ie it has an IPEX connector on it). Unfortunately you will require the eyes of a hawk (or a USB microscope) to "move" the resistor from built-in aerial PCB track to the IPEX connector. But the range difference is astounding. I use them in my attic sensors and they talk to my workshop a good 12m away.
And check you are not using the same channel on your Wifi with other things (normally routers will detect existing WiFi channels and try others but it's worth checking).
Excellent design idea Ralph ... I would have thought by now that all the module makers would have created their own dev-kit with good prototyping connectors but obviously not 😀 .... btw does JLPCB provide a designers gallery where folk could order more copies from and maybe give you as creator a slice of the pie? (Like those t-shirt stores)
Keep up the great work 👍😀
I don't know about the 'sharing' bit (I'll check it out), but this breakout board's Gerber files are available in my GitHub; check out the pinned comment under this video for the location.
Hi Ralph, a humble request: Could you shed some light on porting the Arduino capsense lib to the ESP32 or at least the functionality? The build in touch of the ESP32 is not sensitive enough for some projects, and i cannot figure out how to make a more sensitive capacitance sensor for the ESP32. With the arduino i have no problems. Greetings from the Netherlands.
Why not use a TTP223? I did a video that included them: ua-cam.com/video/jhtY_Hn5jBM/v-deo.html Adjustable sensitivity, auto-calibration and very cheap. Can be hidden behind other bits of hardware (eg a front panel) to disguise them.
If that's not what you want, what you really, really want let me know I'll think again. 😉
After buying (and often returning) several BT modules, I was happy to find this on. Easy connect, true stereo separation (many adverised as stereo are not), tiny size for easy incorpration into other projects. What a winner, and I've only used it as BT receiver so far. I would like to explore that serial connection. I see you used an arduino to make it easier, but are thye TX/RX voltage levels correct?(5V? 3.3V?). Also Regarding the breakout, I've been thinking of getting some SOP24 breakouts to cut in half make wiring easier, but I wouldn't mind getting a few of the boards you made. Are they available? (couldn't find them at the link above).
I used it with a 3v3 ESP32 as a transmitter and it was fine. I can't remember if any voltage shifting was required - always best to check the datasheet for max voltages on pins etc.
Interesting video.I wonder how you get the initial connection to the right device, if there are several available. You may not be able to switch off all of them! Perhaps you need to use the serial interface to select the correct one. Still, a useful gadget. About 13 years ago I was looking for a Bluetooth audio link to connect my computer to my stereo (so I didn't have to have wires running across the room) and they were ridiculously expensive and the reviews where not encouraging. I ended up running flat cables under the carpet!
It will only connect to something that is in pairing mode (which you can control of course). In this demo, it _found_ the Smart Phone Charger (but didn't connect because it wasn't asking for a pairing connection) so I guess it _would_ have connected to my little speaker (in pairing mode) after all. Oh well...
esp32 bluetooth is so interesting 🥳 RemoteXY, esp32, bluetooth, android smartphone are my recent home projects and this #235 video has great information 🧐 thanks 🐱🥠🥂
Glad you found it interesting!
That's what I do with my Smart Heater Controller in my workshop.
Oh, I was looking for a Tx module like this for years and gave up last 11.11 sale when I bought ugreen Tx and Rx devices. But I am definitely checking out this module anyway, so I am interested in breakout PCB.
Ugreen devices are probably nicer, because of aptX capabilities, but I wanted to be able to cotroll transmitter from uC so bad.
Glad I could help. I've noticed a couple of (cheap) BT modules appearing, I wonder why?
@@RalphBacon Just got your letter containing the PCB. Thanks a bunch!
It got here in 21d, just in time with the module itself, so I'll start my tinkering asap.
Made initial tests, transmitter works with cheap MH-28 Receiver that I had. Connects with both Ugreen CM110 and CM402, but neither of them decodes properly, only silent led flashing.
Looks like it is going to be a challenge to find compatible low noise receiver.
Hi Ralph, thanks for the video. Interesting module. Did you ever incorporate this into your web radio design? It would be an interesting addition. I can't find much example projects using this module
Yes I did. The audio output was fed into the BT input and received by a small BT speaker (from Amazon). I described this in a follow up video, I believe, but I may have dreamt it. Very easy to do.
@@RalphBacon thanks for the info. This is a great addition to your web radio project
I wear BT earing aids so of course when they connect to the computer it cuts out the speaker and no body else can heat the sound. Does anyone think it might be possible to use two of these in parallel with each connecting to a separate device? Like maybe 2 BT headsets?
Well, if you paired each BT module with one set of headphones I don't see why it would not always re-connect to the correct (ie the same) device... but there's only one way to prove it.
Hi and thanks for a great video. I was worried about sound delay (latency) with these modules, do you notice that at all?
With standard Bluetooth there will always be a small amount of latency; how much this is a problem depends on your application.
Television lip syncing is the biggest problem, but transmitting instrument sound will also be problematic as the standard delay is anything up to 1/4 second! Very noticeable when watching TV, for example, if you cannot delay the video by that much.
Aptx (which this little module does not support) reduces that to anything starting from 2mS, so quite a difference.
Can you provided details to the cap, led limiter, and connect button you used? Sorry, a newbie here.....
I've responded to your other comment but the cap is a standard 100μF through-hole or SMD 6v (or higher) one, and the resistor a 270Ω 1/4 watt SMD or through-hole (the board supports both formats).
That trace should not cross the antenna. It can change the characteristics such as the resonant frequency . Probably not a big deal in reality but in practice some even have the antenna hang off the edge of the PCB.
I agree. The area around the antenna should be kept clear of anything.
Yes, it's a GND trace added belatedly. I should have routed it manually elsewhere.
Hey, i had an bluetooth radio which i disassembled and it used that same chip, but it also had an mode for fm radio and usb and bluetooth, i plan on ordering one of them again, but in the module form
Sounds like you have an interesting project ahead, Emili!
No PCBs available. Sorry!
NOTE: If you create a comment under this video WITH A LINK then UA-cam will probably delete it. Nowt to do with me. 😨
Would this board be able to receive commands from the bluetooth device it's connected to? Specifically volume up/down, next/previous track, and play/pause, from headphones. It seems to say in the datasheet that the serial tx and rx can to both directions. I've been thinking about making a bluetooth dongle for my minidisc player that can output the headphones command to the remote plug next to the headphone one.
So the audio input to the BT board would come directly from the headphone jack, and any commands from the headphones would be sent via serial to an arduino board that can vary the resistance across the remote jack pins to mimic the wired remote they used to come with.
I'm not sure that this is a two-way transceiver. I've only used it as a BT transmitter. I'm afraid you will have to experiment or find someone who has used it in a two-way setup. 😔
@@RalphBacon ah ok, it might be worth a try. I think bluetooth connections involve some kind of data going both ways?
Well, the responder BT unit will have to confirm that it is connected, and probably send back some kind of acknowledgement of packets received, that's for sure. But the actual data flow, in my projects so far, has been one way only.
@@RalphBacon ok, thanks for that. I'll have to look into this myself haha
@@RalphBaconohhh so it can't be used for a hands-free talking system 🤔
Thank you very much. I have a question. Can this module be connected to two bluetooth speakers at the same time?
Or do you know a module that has this capability?
It connected to "both" (ie Left and Right) earbuds I tried it with. But that's not the same as two separate sets of speakers. In fact, I'm not sure I've ever tried that even with a commercial BT transmitter. You can PAIR them with more than one speaker, but PLAY the same music to both... I just don't know if this is possible, sorry.
@@RalphBacon Thank you for your reply and your time.
Ralph can you make a video on HaLow? about to implement it
I haven't looked at HaLow for IoT stuff yet, but other long distance Wi-Fi solutions are available (LoRa) and ESP-NOW for short-range stuff. I will have to read up on what HaLow brings to the party.
@@RalphBacon thank you
Thank you so much for the info. I've ordered some parts to have a play. I dont suppose its a standardised pcb footprint? 🤓Im more a software engineer than hardware... but loving the crossover 😇
Yes, it is! check for a symbol in EasyEDA by "bpoultier" called KCX_BT_EMITTER_5V. I edited this but I can't remember what changes I made now. The footprint on my PCB was made by "antoniv". Best I can do!
@@RalphBacon thanks so much
Hi Ralph, thanks again for your video. I got hold of one of these modules and wired it to an esp32 to send the AT commands which works really well*, however I'm getting some noise on the audio. I don't suppose you've had this experience?
*NOTE: The AT+CONADD command requires a mac address with 12 chars after the 0x... the solution was to pad the mac address with 0's after the 0x. (i.e. 0x11111111111 => 0x011111111111)
Yes, good point about the 12 character MAC address.
Noise, no none. Do not ground both ends of any audio wires to from the transmitter. So the screen is only grounded at the KCX_BT end.
Check your power supply for noise. Try decoupling the VCC/GND on the breakout board. Let me know (via email, or I'll never find a comment here again) your wiring setup.
Hi Ralph. I was was wondering what the latency with this module is. Thank you!
Difficult to say. I had it connected up to my TV and noticed no lip sync issues. It doesn't use the low latency aptX protocol though. Only way to know for sure is to try it in your particular situation.
Hi Ralph, others have said it as well but that PCB antenna should not have been on top of your custom PCB. Rather there should have been a giant cut-out or the antenna should have stuck outside of the adapter PCB. This to prevent any influence on the bluetooth signal quality and strength. That trace under the antenna is big no-no as well!
There's no ground plane on the breakout board (specifically for this reason) so I doubt the plain PCB will affect the antenna (?), but the single track (a GND line) in that area should have been routed round the edge of the board or something, I agree. Bad Ralph.
@@RalphBacon That there is no ground plane was clear but its still a better design practice to not place the antenna on top of another PCB. Either make a cut-out or place the antenna outside of the adapter board, the last being the preferred option if there are no space constraints of course.
Even though the PCB below it has no ground plane doesn't mean that traces that are routed in the vicinity of the antenna have no influence (they do not even have to run below/under the antenna) as some traces form a (ground) loop. This can act as an unintended (small) antenna which may interfere with the intended frequency the actual antenna is supposed to operate on or produce weird harmonic (RF is a strange and complicated world).
Agreed, my design was not optimal in this respect. 😳
But I've just tried a small antenna plugged into that socket (the type of antenna you can buy for the ESP32 or other BT modules) and it has made a HUGE improvement. So maybe that PCB antenna is quite sensitive to other (nearby) tracks. Live and learn! I will update my GitHub for this project with more details.
Would you recommend this board for an environment where low latency is very important?
Well, it's not aptx compliant (AFAIK) and in my testing I was just transmitting audio from my web radio to a BT speaker unit - where latency just doesn't apply.
I'm guessing if you need low latency you should
(a) check out the specs of this device more closely
(b) see what else is out there that might meet your needs
(c) buy one (they are cheap-ish) and try it out and see!
Whichever route you end up taking, good luck!
i'm trying to transmit to multiple bluetooth speakers simultaneously from one audio source, would this or the esp32 be capable of that? Thanks for the informative video!
Most BT devices have a limit to the number of connections they can support simultaneously. Most BT transmitters support at least two devices (eg for left and right ear buds) but many support more. You need to read the datasheet carefully to see what the simultaneous transmission capability of each device is.
@@RalphBacon thanks, yeah mine are usually 2 also. My objective is to have the esp32 receive the BT signal from the audio source and retransmit it to multiple BT speakers. Perhaps one for each GPIO or something.
Hello, I'm new to bluethoot technology and to building PCB with MCU (if it's in a fact an MCU) I ordered it to make some test on a project. Do you know if I will be able to command it directly solder on a PCB when my design will be done ?
I expect you will be able to program it if you incorporate the necessary push buttons to get the device into AT mode at switch on (just like the modules). Personally, I would use one of the modules and plug that into pin headers on a PCB. That way you KNOW it will work properly.
Sir, is it possible to transmit audio data from ESP32 may be .wav file or any supported format to a wireless bluetooth headset?
Not that I know, which is why I used these modules.
@@RalphBacon It's definitely possible to do it without the modules. You can find info with the search term bellow.
Sending Sound from an ESP32 to a Bluetooth Sink
Hello Ralph, great video on this topic.
I got this mittle device (KCX_BT_EMITTER V1.7 printed on pcb) from amazon.
Connected it to my laptop via usb2serial adapter using 5V setting as Vcc. Using HTerm 0.89 as terminal window, because I was not able to force the actual Arduino IDE to accept the usb2serial adapter as Arduino device.
Now my questions:
I get no connection to the KCX when using 9600 baud.
When using 115200 (8N1) I get every 15s data from the KCX "SCAN...". So connection is working.
I can send AT+ and get "OK+" back, but trying AT+REST or AT+GMR I get "CMD ERR!" back. Any idea on this. Has the V1.7 a totally new set of commands? Or are my com settings wrong? Which are your terminating characters, when sending an AT+ command ? 'cr+lf'?
Appreciate any support. THX
Find some answers:
First the commands are different from yours (AT+RESET, AT+GMR?, AT+BAUD?, AT+STATUS?, AT+PAIR) and second you don't type a `?` at the end of a command, that queries data from the device.
As Sven stated, queries often have a "?" after the command. I've discovered that not all Hayes commands are equal with some manufacturers implementing a different dialect. Confusing or what?
Ralph, How about using a Pi Zero W 2 using Python?
I cannot believe that someone has not already covered this in some detail! Probably on some RasPi channel. [Whilstles] C'mon boy, c'mon Google, over here, good boy.
i'm trying to set it up to connect to one of my bluetooth devices, talking to the module through my arduino Nano. It can find my sony headphones and my samsung buds but it just doesn't want to connect and I cant figure out why. I use the program made by mark-md047 to add the mac adres but to no avail.
Do you've any ideas?
Try this: ensure the only BT device available is the one you want to connect to, and that is in pairing mode. Then turn on the KCX module and wait for a while. If it still doesn't connect press the connect button on the breakout board. That has surely got to work.
@@RalphBacon I have it just soldered up. Found your video after the fact. Do I understand the diagram right that it's a button that ya have to wire to the con and to the ground?
The CON button clears the internal list of previously connected devices and makes it look for something else to connect to - the first thing it can find.
@@RalphBacon the con button did wonders! ty Ralph!
possible transmit audio from a gaming console via bluetooth to external speakers so transmitter to reciever both bluetooth !
I guess that is a possible scenario!
I am wondering if there is a way to use something like this to send audio to 2 separate speakers? I have a pair of non powered 100 watt speakers with 1/4 inch (guitar type) jacks on the back. They are high efficiency, so they will fill a room with 10 watts input. I would like to place them in different parts of the room and enjoy stereo audio without tripping on cables. So I would need something that has BT input that drives 10 to 50 watts and has a left/right switchable output.
Can the board you demo'ed in the video pair to 2 separate devices at the same time?
or would I need to make my speakers act as master and slave?(I hope not)
What is the fidelity of the BT board in your video?
If you have two speakers that can receive BT signals then you could use two transmitters with just one of the channels (Left/Right) being transmitted by each module, could you not?
But you would need an amplifier per speaker (you'll soon find one in the Asian warehouses) plus power supply thus turning your passive speakers into active ones! And they will need to be plugged in somewhere too so not entirely cable free - unless the amplifier was close to the power socket and you just sent the speaker signal to the speaker (same number of wires, ie two).
Fidelity is good, no perceptible background noise or hum etc but then again I'm listening to web radio in the bathroom! Oh, I did try this module on my TV to headphones and they were very good in that case too.
@@RalphBacon The speakers I have are (old school) 8ohm 100watt high effeciency speakers.. So I guess your first paragraph is best answer. I just need a separate (BT rec/amp circuit) for each speaker, then the corresponding transmitter for each one. Thanks
Can you recomend a good BT reciever able to drive 10 watts or more into 8 ohms? Would I be able to name the BT recievers as LeftSpeaker and RightSpeaker?
I found a device that has a number: HW-407
Do you know anything about it?
It's an inexpensive BT receiver (stereo) but you would still need one per speaker AND have to connect a mono amplifier to it for each speaker. More details: amzn.to/32r5IFl and www.banggood.com/custlink/GDKYbib5v1
You could try looking on Banggood for a complete BT receiver and amplifier (Banggood do offer more 'complete' units than AliExpress' modules) although I suspect they will all be stereo and you would then need two if you don't want to connect one speaker to the other.
hello sir i have a question, where did you find the CAD model for making the pcb ?? because i shearch in all the web site i know and didn't find it, and i'm affraid to draw it by and because the last time i did that it failed. thx
I pretty sure I made my own footprint/component. Worked well enough!
Nice board Ralph, should that cap read 100nF ? or are the holes for 100uF.....cheers.
It should be for (up to) 100µF but I think I put a much smaller one in there just for decoupling.
Cheese!!!!!!!!!
@@fredflintstone1 SQUEAK!!!!
Good video!!! i have a cuestion for you, is it possible to obtain de RSSI information of this transmitter? Thank you
The receiver module that you use might already have this functionality - or you might have to build one yourself with a simple BT receiver module. You phone might have an app available to do this too, I use one for Wi-Fi so maybe someone has built one for BT too?
Hi Ralph. Great video! I used this very module for a CD player project and it works great. However, I wanna embed it now in a PSP to use it with my earbuds, but I can't find the way to manage the earbuds volume. Has anybody found out which AT commands handle that? I'd attach a board with an Atmega and the KCX_BT_EMITTER, intercept the PSP volume buttons and send the AT commands accordingly. However, I can't find any info :S. There must be a way to send "next track", "previous track", "start", "stop", "volume+", etc.
What are you sending those commands to (NEXT, PREV etc)? The KCX is only a BT transmitter, you can't send those sort of commands to it.
@@RalphBacon I'd want the KCX to receive those inputs and tell the receiver via bluetooth to increase/decrease the output volume. The same way a phone tells its bluetooth earbuds to increase/decrease volume. I know it's a BT transmitter, but BT can be used to transmit data as well as audio. Many bluetooth devices allow for data transfer of actions such as play/pause being sent from receiver to transmitter or volume management, which happens the other way around. I thought there might be a way to tell the KCX using AT commands to tell the receiver to increase the volume.
I have 2 of these modules in my drawer. Nicely stowed away after I saw the pitch. Why didn't they make these when I was like 20 years old and my eyes were 150%?
Guess if I order from the UK the customs might tax me big time.
And you are right with your warning about including YT links. I tend to give comments that are rather larger than the average, since sharing is caring, and it is extremely frustrating to find that the posting has been removed after all the work has been put into it.
Not sure why you haven't tried a DC-DC isolator that are widely available. Transformers tend to have some loss and also be non linear in frequency.
You can get one of my breakout boards without customs issues as I will send it as a gift - no money is changing hands! If you want one, let me know your full postal address, Luc. No magnifying glass included, sorry!
@@RalphBacon Nice just send you an email. Next to the Flukes and others I have the same meter. Guess which one I tend to use for all my low voltage projects, yup that one. It is lighter, smaller than my Fluke's, almost as quick and still precise after having used it almost every day for 3 years. For the price it is a no brainer.
I am trying to use a similar chip for a BT project of mine in a Gameboy, there are tons of tutorials online about this but none of them show a way to turn off the stock speaker on the gameboy when this chip is turned on... Would you happen to have any idea about how someone would go about doing this? there is a headphone jack on the Gameboy but it uses a mechanical switch in the headphone port to switch off the speaker rather than through an electrical connection. So if you install this it keeps the stock speaker on and you have BT at the same time which is not the desired result I'm looking for. I want the speaker to shut off when I turn on the chip or pair my headphones.
I've had a similar situation; I just got a pair of earphones and plugged them into the device to shut it up, and listen to better quality via the BT method.
You could also just use a spare jack plug, not a complete set of headphones to do this. Simple and fairly unsophisticated, but it does the job!
Hi Ralph, is there an error on the silkscreen - it states 100uF cap is this correct value?
It's just room for some sort of (optional) decoupling/smoothing capacitor, Lee. I use 100uF in my web radio implementation but only a 100nF on my test board - both seem to work equally well. Btw do read what I've put on the GitHub about the use of a small aerial, makes a huge difference in range.
@@RalphBacon Cheers Ralph, much appreciated.
I'm really curious if a module like this could be used to mod Bluetooth into an iPod classic
Do we still need an iPod classic these days? Surely our phones are much more capable? Just sayin'!
@@RalphBacon yes 100% but I like having a dedicated music device and offline storage for songs I've already done a SD card mod to it and was curious if this little module would give it Bluetooth it's more of a hobby seeing what I can do to it
Just hooked it up to my 4th gen iPod, haven't integrated it yet (just prototyped it). But got it running, headphone jack and Bluetooth runned fine. The bluetooth has a bit of a delay.
Just doubting if I'm going to integrate the con button with the lock - unlock switch.
If you want to transmit audio from your ESP32, why aren't you using the inbuilt Bluetooth? Why would you need an external Bluetooth transmitter when it's all on the same piece of silicon?
The inbuilt BT in the ESP32 is apparently not optimised for audio.
Hello Ralph. I am interested in a BT TO breakout board. South Africa?
Sure, send me an email. Found here: ua-cam.com/users/RalphBaconabout
Hi, what is the current draw running at 5 volts?
I found this on the Internet:
KCX-BT emitter Features:
Power Supply: 3.3~5.5V
current: 35mA
Transmission rate: 2000Kbps
Much more here:
bit.ly/3uMpPZ3
Can you use the built in esp32 bluetooth functionelity for this?
Probably not. I haven't heard about Bluetooth A2DP profile being implemented on ESP devices.
As Leeroy says, BT _audio_ is (probably) not available on the ESP32 - but I will look into what the BT can do on this module at some future date.
@@Mr.Leeroy Theres a ESP-IDF A2DP-SINK demo in the IDF examples folder. The example uses Bluetooth classic A2DP for audio stream reception. Espressif says you have to use and external i2s or internal DAC (8 bit) for output to a speaker.
@@noweare1 I just realized couple hours ago that I was wrong and replied here to correct myself but apparently YT zapped my post with anti-spam.
You are right. I found ESP32-A2DP lib by pschatzmann
.
If the standard ESP32 can send BT audio that would be a start but then we would still need an I2S decoder so probably no advantage after all?
Could you not use the esp32 was it not possible to use the blutooth on the ESP 32?? or am I missing something😉
I don't think the ESP32 has the capability for streaming BT _audio_ but I might be wrong. I would have to research this (again).
@@RalphBacon I know the esp32 supports bluetooth classic which is 2Mbps and used for audio. I had the same question. I don't think you can use BT Classic and BLE at the same time though.
@@RalphBacon it can recieve the signal but you would have to figure out how to decode and amplify it likely with some external decoder reading off i2s
Anyone have a good source for a KCX_ BT_ EMITTER footprint?
What PCB CAD program are you using? I designed a small breakout board for this device as part of this video which I can let you have in EasyEDA format if you want. Email me!
How does the break off antennas work?
"Break off" antenna? Hmm. Is this really what you mean? There is no break off antenna.
Do you mean "external" antenna (that plugs into the tiny IPEX or UFL connector)?
What is your real question?
But….doesn’t the ESP32 already have BT ? 🧐
The ESP32 has BT but doesn't decode the final signal. Thus, if we still need another module to do that (I2S) we might as well use this one that does the whole job very well (even better with an external aerial, see my GitHub for what I use which has transformed the device).
can you make video for bluetooth audio transmitter and reviser for speaker by using this. i you make i love it and please reply
I'm not clear what you're asking here! This video is all about a BT audio transmitter; I don't have plans for a BT audio receiver unit (with a speaker) because you can buy them so easily for just a few dollars (or a lot of dollars for better quality) from Amazon and the likes. I showed one in this video IIRC.
I AM SCHOOL STUDENT. i wank to make low cost Voice Amplifier Speaker with Microphone for Teachers because in india it about 2500rs and more. so could you guide me how to bluetooth vioce amplifer work and how to make it own. anyway thank for reply sir
@@RalphBacon
I'm afraid I don't have the resources to design bespoke projects but I do have a question for you. Why Bluetooth? Why not just a simple audio amplifier with microphone and speaker? Much cheaper and simpler too.
Hi Ralph.
Please may I get in line for a breakout board.
Thanks John.
You're in! Obvs, given that you have built my ESP32 Web Radio! Send me your address via email please.
@@RalphBacon Thanks Ralph. Sent details on the email address we used before.
On its way, John.
Thank you Ralph look forward to using this. I Already use a Bluetooth speaker, but with a line out connection. Be nice to get rid of another wire.
Is this has mic to communicate with android phones
No microphone on the board but you can feed in a (pre-amplified) microphone input.
Did you find a datasheet?
Yes, links to the documentation I found are in my GitHub:
github.com/RalphBacon/235_KCX_BT_EMITTER-Breakout-Board
i am waiting when they will bring BT usb emilator in ali, so that i can connect my kbd / mouse / printer to it :/
If they haven't invented it yet, I'm sure they will soon 😁
Why not use the blue tooth on the esp32
Apparently it is not good for _audio_ BlueTooth transmission (no idea why).
You can't use WiFi and BT in parallel on ESP32
Where can I get the break out board?
The Gerber files of my board are in the GitHub for this video (github.com/RalphBacon/235_KCX_BT_EMITTER-Breakout-Board ) which you can then order from the PCB supplier of choice, but JLCPCB is top notch (and inexpensive).
If this makes no sense at all (I see you describe yourself as a newbie in another post) email me (read the video description of a more recent video to find it) and I'll walk you through it.
@@RalphBacon thanks. I was able to figure that out after reading more comments. I have some ordered. What about the button, cap, and led limitter?
A standard 100μF cap, 6V or more (not too much more or it will be enormous), 220Ω-ish resistor and the button is fairly standard SMD button, just sits on top of the board, you'll find them used as reset buttons on many PCBs.
"Telly" is television? OK, fine, but how many maths do you have?
We have many 'maths' unlike US residents who have to make do with a meagre, single 'math' (probably because they can't handle any more) 😁
BBC long day, Ralph? OMG! Try Joe Rogan on Spotify. Warning: Main stream media doesn't like Joe Rogan just FYI. Dr. Robert Epstein was just on Rogan, I know you would find that show interesting.
Love your content.
Take care.
why because Rogan is a real flipping idiot, unvaxxed delusional ... alternative medicine ...
I'll check it out later, thanks!
@@RalphBacon The most recent one, Dr. Robert Epstein is a Google/Big Tech eye opener. I often think that I'm a small fish in this world so why should I care, but nevertheless, imagine what big tech (especially Google) have on young people who just might run for political office or be the next CEO of whatever big company. They have logged everything you have ever done. Europeans are a bit insulated from Google, but no doubt they log what they can. Joe does a lot of very interesting long form interviews and main stream media hates him, because he has over 12 million listening to each show. Spotify signed him to a 10 year contract for 100 million dollars.
@@RalphBacon If you check out Rogan, put on your critical thinking cap. He is ultra right wing. He will tell you to take drugs that don't work for covid. He will tell you not to take the vaccines for covid. This guy's suggestion of Rogan tells all you need to know about him.
Hi Ralph, Finally got round to completing the KCX_BT_EMITTER-Breakout-Board (it’s only taken a year). I have set up to test its response to AT commands as per your video (235). (5V ON VCC and TX RX via FTD1232)
Despite the board being discovered, I have not been able to get it to connect and wonder if you have any thoughts that might help me to move forward please?
ALL Devices=0
Delete_Vmlink (Note after pressing CONNECT)
ALL Devices=0
ALL Devices=0
ALL Devices=0
ALL Devices=0
ALL Devices=0
New Devices:1,MacAdd:0x00c8ac91bd7,Name:Bose Mini SoundLink
ALL Devices=1
MacAddr=0x00c8ac91bd7,Name=Bose Mini SoundLink
ALL Devices=0
ALL Devices=0
New Devices:1,MacAdd:0x00c8ac91bd7,Name:Bose Mini SoundLink
ALL Devices=1
MacAddr=0x00c8ac91bd7,Name=Bose Mini SoundLink
ALL Devices=0
As you will observe my device is discovered, but then immediately disconnects. This continues for around 4 iterations after which it reverts to reporting ALL Devices=0. Predictably the blue LED flashes quickly throughout the process. I have tried “AT+CONADD=0x000c8ac91bd7” to no affect. Any pointers appreciated.
The first time you ever power up (too late now, I guess) it will connect to whatever is waiting to pair with it. If you thereafter press the CON button (or momentarily short the contacts) it will clear the memory and start as described above. Ensure you have the item you want to connect to in pairing mode. After that it will connect to the same device each time.
Some items will not connect to this device, but I don't have details of why or which ones. BT speakers should, on the whole, be OK.
Glad to report I finally have the KCX_BT_EMITTER board working. The problem? As you mentioned in your reply ‘some items will not connect to this device’. My Bose Soundlink Mini is just one of these devices. After obtaining an alternative unit it now works faultlessly.
I think this illustrates an interesting point: as amateurs, most of us learning as we proceed, there is a tendency to assume any fault will be a result of a mistake of our own making. The odds are that this will often be the case, but not every time. So perhaps we we should learn that there comes a point when fault finding, to stop, take stock and consider the idea that the fault might may well not be our build but some other external factor. Faith in our own ability (with you guidance) is worth a lot.
Do you know details on the cap, led limiter, and connect button he used?
@@engindude25 Hi, I have used a 220M Ohm Led Limiter resistor. I cannot remember why so high (Ralph suggests around 220 Ohm) but that’s what I have and it works.
The capacitor is 100uF 6.3v Electrolytic (Because I had one in the spares box)
Good video.. how can i kontakt you, i have a project i need help to.. mvh jesper dk.
My ABOUT page with email address: ua-cam.com/users/RalphBaconabout