This example is about a node transferring data via a RFM69 to a gateway. The format of the packets are described below. They're flexible and can vary for each node (type). On the gateway a rule should be defined accordingly (by node or node type) to understand the data received.
A datapacket consist of a type/len byte followed by len data bytes. The 1st byte defines what kind of packet it is (4bits) and how long it is (4bits).
A node can therefore send and receive 16 different types of datapackets each, which can be up to 16 bytes long. Types 0-7 are reserved for generic types, 8-15 are node dependent.
| type | name | length | description |
|---|---|---|---|
| 0x00 | debug | 1 | used to debug, eg as counter |
| 0x01 | vcc | 2 | voltage of power source, 522 = 5.22v |
| 0x02 | temp | 2 | temperature on pcb, p.475 in datasheet |
| 0x03 | rssi | 1 or 2 | RSSI ctrl, [ last received RSSI as uint8_t ] |
| ... | |||
| 0x08 | humidity | 1 | relative humidity in % |
| 0x09 | temp | 2 | temperature on sensor, 225 = 22.5°C |
| 0x0a | threshold | 1 | new threshold on which humidity value means "dry" |
| type | name | length | description |
|---|---|---|---|
| 0x00 | debug | 1 | used to debug, eg as counter |
| 0x01 | timestamp | 4 | current timestamp |
| 0x02 | |||
| 0x03 | rssi | 1 or 2 | RSSI ctrl, [ last received RSSI as uint8_t ] |
| 0x0a | threshold | 1 | new threshold on which humidity value means "dry" |
The RSSI ctrl byte gives information about power transmission:
- the lower 4 bits define the amount of change to the power transmission
- ctrl byte
| bit | mask | name | description |
|---|---|---|---|
| 7 | 0x80 | limit | set if node reached a limit (0 or 23) so the gateway doesn't send more changes |
| 6 | 0x40 | reset | set to request a reset of the atc, eg on startup of the node |
| 5 | 0x20 | request | set to request the last rssi value. Should be sent with the next transmission |
| 4 | 0x10 | res | for future use |
