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141 lines
5.1 KiB
141 lines
5.1 KiB
# Read GPS data - Wio Terminal
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In this part of the lesson, you will add a GPS sensor to your Wio Terminal, and read values from it.
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## Hardware
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The Wio Terminal needs a GPS sensor.
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The sensor you'll use is a [Grove GPS Air530 sensor](https://www.seeedstudio.com/Grove-GPS-Air530-p-4584.html). This sensor can connect to multiple GPS systems for a fast, accurate fix. The sensor is made of 2 parts - the core electronics of the sensor, and an external antenna connected by a thin wire to pick up the radio waves from the satellites.
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This is a UART sensor, so sends GPS data over UART.
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### Connect the GPS sensor
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The Grove GPS sensor can be connected to the Wio Terminal.
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#### Task - connect the GPS sensor
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Connect the GPS sensor.
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1. Insert one end of a Grove cable into the socket on the GPS sensor. It will only go in one way round.
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1. With the Wio Terminal disconnected from your computer or other power supply, connect the other end of the Grove cable to the left-hand side Grove socket on the Wio Terminal as you look at the screen. This is the socket closest to from the power button.
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1. Position the GPS sensor so that the attached antenna has visibility to the sky - ideally next to an open window or outside. It's easier to get a clearer signal with nothing in the way of the antenna.
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1. You can now connect the Wio Terminal to your computer.
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1. The GPS sensor has 2 LEDs - a blue LED that flashes when data is transmitted, and a green LED that flashes every second when receiving data from satellites. Ensure the blue LED is flashing when you power up the Pi. After a few minutes the green LED will flash - if not, you may need to reposition the antenna.
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## Program the GPS sensor
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The Wio Terminal can now be programmed to use the attached GPS sensor.
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### Task - program the GPS sensor
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Program the device.
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1. Create a brand new Wio Terminal project using PlatformIO. Call this project `gps-sensor`. Add code in the `setup` function to configure the serial port.
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1. Add the following include directive to the top of the `main.cpp` file. This includes a header file with functions to configure the left-hand Grove port for UART.
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```cpp
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#include <wiring_private.h>
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```
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1. Below this, add the following line of code to declare a serial port connection to the UART port:
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```cpp
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static Uart Serial3(&sercom3, PIN_WIRE_SCL, PIN_WIRE_SDA, SERCOM_RX_PAD_1, UART_TX_PAD_0);
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```
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1. You need to add some code to redirect some internal signal handlers to this serial port. Add the following code below the `Serial3` declaration:
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```cpp
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void SERCOM3_0_Handler()
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{
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Serial3.IrqHandler();
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}
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void SERCOM3_1_Handler()
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{
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Serial3.IrqHandler();
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}
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void SERCOM3_2_Handler()
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{
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Serial3.IrqHandler();
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}
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void SERCOM3_3_Handler()
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{
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Serial3.IrqHandler();
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}
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```
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1. In the `setup` function below where the `Serial` port is configured, configure the UART serial port with the following code:
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```cpp
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Serial3.begin(9600);
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while (!Serial3)
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; // Wait for Serial3 to be ready
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delay(1000);
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```
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1. Below this code in the `setup` function, add the following code to connect the Grove pin to the serial port:
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```cpp
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pinPeripheral(PIN_WIRE_SCL, PIO_SERCOM_ALT);
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```
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1. Add the following function before the `loop` function to send the GPS data to the serial monitor:
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```cpp
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void print_gps_data()
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{
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Serial.println(Serial3.readStringUntil('\n'));
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}
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```
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1. In the `loop` function, add the following code to read from the UART serial port and print the output to the serial monitor:
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```cpp
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while (Serial3.available() > 0)
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{
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print_gps_data();
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}
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delay(1000);
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```
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This code reads from the UART serial port. The `readStringUntil` function reads up until a terminator character, in this case a new line. This will read a whole NMEA sentence (NMEA sentences are terminated with a new line character). All the while data can be read from the UART serial port, it is read and sent to the serial monitor via the `print_gps_data` function. Once no more data can be read, the `loop` delays for 1 second (1,000ms).
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1. Build and upload the code to the Wio Terminal.
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1. Once uploaded, you can monitor the GPS data using the serial monitor.
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```output
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> Executing task: platformio device monitor <
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--- Available filters and text transformations: colorize, debug, default, direct, hexlify, log2file, nocontrol, printable, send_on_enter, time
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--- More details at http://bit.ly/pio-monitor-filters
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--- Miniterm on /dev/cu.usbmodem1201 9600,8,N,1 ---
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--- Quit: Ctrl+C | Menu: Ctrl+T | Help: Ctrl+T followed by Ctrl+H ---
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$GNGGA,020604.001,4738.538654,N,12208.341758,W,1,3,,164.7,M,-17.1,M,,*67
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$GPGSA,A,1,,,,,,,,,,,,,,,*1E
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$BDGSA,A,1,,,,,,,,,,,,,,,*0F
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$GPGSV,1,1,00*79
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$BDGSV,1,1,00*68
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```
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> 💁 You can find this code in the [code-gps/wio-terminal](code-gps/wio-terminal) folder.
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😀 Your GPS sensor program was a success!
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