many many years ago we developed and sold a pair of products called ez-key (https://www.adafruit.com/product/1535) and ez-link (https://www.adafruit.com/product/1588) that implemented bluetooth classic HID and SPP respectively. they were popular because we actually did the two ‘right’ – with SPP having control lines for remote programming of boards that would normally use the RTS/DTR/CTS lines for auto-reset control.
to do the initial development we had to source CSR chipset BT modules, get them FCC certified and then develop for them using the very-unpleasant-and-totally-nda’d CSR firmware package and IDE. and then our module supplier closed shop and everything got extremely annoying to replace and recertify and we ended up discontinuing the line.
however, perhaps we can bring it back from the dead with ESP32 pico modules, small enough to make for tiny lil boards and with BT classic support and without a nonsense sdk. best of all there’s a version of the pico that can use external antennas for looooong range bluetooth!
here’s a respin on the classic: its much smaller, but has the same pinout and capabilities. the pair LED is now a neopixel so we can have more statuses. the hardware uart on the esp32 is what we use for rx and tx. the pair button uses gpio 0 so we can use it for programming the board itself if we want to update the firmware. we strapped gpio 15 to ground, which should turn off the boot message so its a clean uart pipe over SPP. we’ll see if this works!
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