+static uint8_t encode4Bits(const uint8_t b)
+{
+ uint8_t c = b & 0xF;
+ // OTA, the least significant bits first
+ // The columns are
+ // 1 - Bit value to send
+ // 2 - Reversed (big-endian)
+ // 3 - Encoded
+ // 4 - Hex values
+
+ switch(c){
+ // 1 2 3 4
+ case 15: return 0x55; // 1111 -> 1111 -> 01010101 -> 0x55
+ case 14: return 0x95; // 1110 -> 0111 -> 10010101 -> 0x95
+ case 13: return 0x65; // 1101 -> 1011 -> 01100101 -> 0x65
+ case 12: return 0xa5; // 1100 -> 0011 -> 10100101 -> 0xa5
+ case 11: return 0x59; // 1011 -> 1101 -> 01011001 -> 0x59
+ case 10: return 0x99; // 1010 -> 0101 -> 10011001 -> 0x99
+ case 9: return 0x69; // 1001 -> 1001 -> 01101001 -> 0x69
+ case 8: return 0xa9; // 1000 -> 0001 -> 10101001 -> 0xa9
+ case 7: return 0x56; // 0111 -> 1110 -> 01010110 -> 0x56
+ case 6: return 0x96; // 0110 -> 0110 -> 10010110 -> 0x96
+ case 5: return 0x66; // 0101 -> 1010 -> 01100110 -> 0x66
+ case 4: return 0xa6; // 0100 -> 0010 -> 10100110 -> 0xa6
+ case 3: return 0x5a; // 0011 -> 1100 -> 01011010 -> 0x5a
+ case 2: return 0x9a; // 0010 -> 0100 -> 10011010 -> 0x9a
+ case 1: return 0x6a; // 0001 -> 1000 -> 01101010 -> 0x6a
+ default: return 0xaa; // 0000 -> 0000 -> 10101010 -> 0xaa
+
+ }
+}