Protocols used to talk between an embedded CPU and a PC

Host -->  [V02?]      // Request voltage #2
AVR  -->  [V02=2.34]  // Reply with voltage #2
Host -->  [V06=3.12]  // Set voltage #6
AVR  -->  [V06=3.15]  // Reply with voltage #6

struct PacketHdr
{
  char syncByte1;
  char syncByte2;
  char packetType;
  char bytesToFollow;  //-or- totalPacketSize
};

struct VoltageSet
{
   struct PacketHdr;
   int16 channelId;
   int16 voltageLevel;
   uint16 crc;
};

struct VoltageResponse
{
   struct PacketHdr;
   int16 data[N];  //Num channels are fixed
   uint16 crc;
}

V0=3.20
  V1=3.21
  V2= ...
  D1=0
  D2=1
  D3=...
  and then start over --

5=0
6=9
2=5