Just an bluetooth audio board like the XY-BT-MINI, etc.
On the board the pins are utilized as follows:
Pin | Usage | Note |
---|---|---|
PB5 | Onboard LED | |
PC5 | Mute | Driven high when no sound is playing |
USBDM/PC3 | USB D- | Exposed on a pad on back side (next to VCC) |
USBDP | USB D+ | Exposed on a pad on back side (next to GND) |
Extra functions that are available in the firmware my board shipped with:
Pin | Usage | Note |
---|---|---|
PA0/PA2 | Mic bias | |
PA1 (MIC) | Microphone | |
PA3 | Line in L | |
PA4 | Line in R | |
PB4 | ? | |
PB6 | Line in sense | Active low |
PB7 | ? | |
PC4 | ADKEY | Pulled up by an external 22k resistor on board |
ADkeys are as follows:
Resistance | Key | < long press |
---|---|---|
0R | Prev | Vol- |
3k | Play/Pause | Mode |
6k2 | Next | Vol+ |
9k1 | Mode | |
24k | Repeat | |
33k | EQ | |
51k | Vol+ | Vol+ |
100k | Vol- | Vol- |