RS485 TX       1 d1/tx/pd1               Vin  1   Vin
   RS485 RX       2 d0 rx/pd0               GND  2   GND
                  3 reset/pc6             reset  3
   GND            4 gnd                     +5V  4   +5V
   RS485 DE/RE    5 d2/pd2                   a7  5
   Echo D3        6 d3/pd3                   a6  6
   Echo D4        7 d4/pd4               pc5/a5  7   LED 1
   Echo D5        8 d5/pd5               pc4/a4  8   Trig C
   Echo D6        9 d6/pd6               pc3/a3  9   Echo C3
   Trig D        10 d7/pd7               pc2/a2 10   Echo C2
   Echo B0       11 d8/pb0               pc1/a1 11   Echo C1
   Echo B1       12 d9/pb1               pc0/a0 12   Echo C0
   Echo B2       13 d10/pb2                aref 13
   Echo B3       14 d11/mosi/pb3            3V3 14
   Trig B        15 d12/miso/pb4    pb5/d13/sck 15   LED 2