===== TGnet Zigbee protocol =====
I settled on channel 16 at 9600 baud for the initial control netwrok.

Protocol is as follows:

|0x7f|Pac synch 1|
|0xfe|Pac synch 2|
|0xdd|Destination address|
|0xss|Source address|
|0xnn|Packet Length|
|0xop|Op code |
|0xxx - 0xyy|data |
|0xcc|CRC LSD byte|
|0xcc|CRC MSD byte|

  * Packet length is entire length including 2 synch bytes and 2 crc bytes

Address assignments:
|Bonnard Master|0x01|
|Burbank grow box|0x02|
|Burbank garage status|0x03|