Implementation for STM32WL

[happytm]

Thank you for your efforts for license free long range audio transmissions for emergencies.

It would be nice to have this implemented on STM32WLE5CCU6 chip. There is an inexpensive Ebyte module linked below with built in LoRa for simplicity.

It does have 12 bit ADCs for microphone input and single DAC for audio output.

https://www.cdebyte.com/products/E77-900M22S/2

or

https://www.aliexpress.us/item/3256805558901791.html?src=google&src=google&albch=shopping&acnt=708-803-3821&slnk=&plac=&mtctp=&albbt=Google_7_shopping&albagn=888888&isSmbAutoCall=false&needSmbHouyi=false&albcp=20123152476&albag=&trgt=&crea=en3256805558901791&netw=x&device=c&albpg=&albpd=en3256805558901791&gad_source=1&gclid=Cj0KCQiAyeWrBhDDARIsAGP1mWS4KRjapS07nC1aphLKKmmf-IKzsKdOoLu4Fcfko1lT8m7N8QNgXmIaAkWPEALw_wcB&gclsrc=aw.ds&aff_fcid=7a6de1e9b8ad44969e38b58c7f1a1ff1-1702514768527-00881-UneMJZVf&aff_fsk=UneMJZVf&aff_platform=aaf&sk=UneMJZVf&aff_trace_key=7a6de1e9b8ad44969e38b58c7f1a1ff1-1702514768527-00881-UneMJZVf&terminal_id=bff5be4fdbcf427b9e92b442d86ba01e&afSmartRedirect=y&gatewayAdapt=glo2usa

If this is possible, It can be smallest long range walkie-talkie with simplest design.

Thanks.

[sh123]

@happytm , I'm not sure 48 MHz CPU will be enough, on ESP I could not get Codec2 performing well on time at 80 MHz, maybe OPUS is going to work... but probably some delicate low level porting/optimization is needed for STM, need to order couple devices and try out..

[happytm]

Thank you for your response.

I you are located in USA I could ship you couple of Ebytes units.

I am not sure about flash size of 250k on these modules is enough to fit whole codec and LoRa related code.

Thanks.

[happytm]

@sh123 Were you able to get E77 modules?

Thank you.

[sh123]

Hi, very busy lately, did not have time to play with that..

[happytm]

OK. Thanks.

[happytm]

I have couple of E-77 modules:

If you can spare some time and give some hints I can experiment with them using Opus codec.

Thanks.

[happytm]

Looks like they have new module which can be suitable for low footprint walkie-talkie using Opus codec:

https://www.cnx-software.com/2025/06/09/6-5-rak11160-lorawan-wifi-and-ble-module-pairs-esp32-c2-with-stm32wle5-for-low-power-long-range-iot/