headers:

left

GND     -  STM32
GPIO_B <-  STM32 B9
GPIO_A <-  STM32 B8
5V      -> STM32
LED_D   -> STM32 B7
LED_C   -> STM32 B6
LED_B   -> NC
LED_A   -> NC


middle

GND     -  NC
NC      -  NC
NC      -
PIC RX <-  STM32 B10
PIC TX  -> STM32 B11
*RESET <-  STM32 B1


right

5V  -> MR3020
NC
GND -  MR3020