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RNode GPS
This currently targets an experimental T-Beam firmware: https://github.com/faragher/RNode_Firmware
This uses the uBlox NEO-6M and may not be compatible with any other modem, since the NEO-6M has NMEA standard output, but proprietary control codes.
Data is sent to to and received from the RNode over UART. (Default 115200 Baud, 8N1)
RNode command codes are subject to change.
This is designed to pass NMEA sentences from the radio to the computer attached over the RNode. It is not intended to be a high-precision stand-alone device and lacks things like satellite lists, DoP, or NTP capabilities. Onboard time and location information is designed for on-RNode display purposes or for super-low power capabilities, such as ATMega systems controlling the RNode.
Additional on-board features are not expected. Support for additional modems is possible given a known control code standard.
| Frame End | RNode Command | GPS Opcode | Frame End |
|---|---|---|---|
| FEND | CMD_GPS_CMD | X | FEND |
| 0xC0 | 0xA0 | X | 0xC0 |
X: See command list below
| Frame End | RNode Command | Sentence Type | Rate | Frame End |
|---|---|---|---|---|
| FEND | CMD_GPS_RATE | X | Y | FEND |
| 0xC0 | 0xA1 | X | Y | 0xC0 |
X: Target NMEA sentence Y: Rate divisor 0-9
Divisor cuts the rate of messages, 1/n, but is dependent on the internal modem rate. This is a hardware limitation. May be increased to 0-99 with further testing.
| Num | Sentence |
|---|---|
| 0 | GGA |
| 1 | GLL |
| 2 | GSA |
| 3 | GSV |
| 4 | RMC |
| 5 | VTG |
| Code | Name | Description |
|---|---|---|
| 0x00 | GPS_CMD_TIME | Returns UTC time in a six character string. - 001122 |
| 0x01 | GPS_CMD_LOCATION | Returns location as a string. dd mm.mmm N 0x0d 0x0a ddd mm.mmm W |
| 0x02 | GPS_CMD_RATE | Defined but unused. Reserved for future output |
| 0x03 | GPS_CMD_SENTENCE | Instructs the RNode to request and return a GGA message. Triggers all stored messages |
| 0x10 | GPS_CMD_ENABLE_HEARTBEAT | Convenience: Sets GGA pole rate to 1 and Automatic to true |
| 0x11 | GPS_CMD_DISABLE_HEARTBEAT | Convenience: Sets GGA pole rate to 0 and Automatic to false |
| 0x12 | GPS_CMD_ENABLE_AUTOMATIC | Reports all NMEA messages as they arrive |
| 0x13 | GPS_CMD_DISABLE_AUTOMATIC | Reports messages only on request |
| 0x20 | GPS_CMD_HOT | Convenience: Sets GGA, GLL, RMC, and VTG to rate 1 |
| 0x21 | GPS_CMD_COLD | Convenience: Sets all sentences to rate 0 |