The ublox neo 6m GPS receiver
Most GPS receivers use a UART to communicate with their hosts and the Neo 6M is no exception. The ESP32 has 3 hardware UARTs with the following default connections:
| UART number | default Rx, Tx, GPIO pins |
|---|---|
| 0 | 3,1 |
| 1 | 9,10 |
| 2 | 16,17 |
On our system UART 0 is reserved for REPL, GPIO 9 and 10 are not pulled out to the connector and GPIO 16,17 are used by PSRAM. Fortunately the ESP32 allows to re-map UARTs to just about any GPIO pin using the GPIO matrix and the MicroPython driver supports the re-mapping. We can define a UART as follows: uart2=machine.UART(2, baudrate=9600, rx=21, tx=22, timeout=10000) For more information about the ESP32 UART driver in MicroPython see https://docs.micropython.org/en/latest/library/machine.UART.html#machine-uart The card on which the Neo 6M GPS receiver is mounted has 4 connection pins (starting from the left): UART number | default Rx, Tx, GPIO pins
| Pin on Neo 6M | Pin on ESP32 bus |
|---|---|
| Vcc | 3.3V |
| Rx | Rx: D1 = GPIO 22 |
| Tx | Tx: D2 = GPIO 21, only needed if you want to modify parameters on the Neo 6M |
| Gnd | Gnd |
Only Pin D2 or GPIO 21 is actually used and as you can tell from the instantiation of UART2 shown above the Neo 6M receiver communicates on 9600 baud.
Here is a photo of the device:
