GPS STM32 library

This project demonstrates how to use the STM32 NUCLEO-H7A3ZI-Q with the Adafruit Ultimate GPS HAT to read and process GPS data via UART. The code leverages the leech001/gps repository as a foundation for GPS data parsing and communication.

This repository now serves as documentation of how I configured the GPS module with the microcontroller. I hope it can help others who are starting with GPS and STM32 development.

Hardware and Software Configuration

Step 1: Open the .ioc File in STM32CubeIDE

• Launch STM32CubeIDE and open the .ioc file for the project.

Step 2: Enable and Configure USART1

1. Navigate to Pinout & Configuration.
2. Under the peripherals list (A → Z), search for USART1.
3. Enable USART1 in Mode as Asynchronous.
4. Go to NVIC Settings and check the box for USART1 global interrupt (as shown in the image below).

5. In Parameter Settings, set the Baud Rate to 9600 Bits/s (as shown in the image below).

6. Adjust GPIO Settings for USART1 as shown in the image below.

Step 3: Adjust Code Generation Settings

1. Go to Project Manager → Code Generator.
2. Uncheck the box for Generate peripheral initialization as a pair of .c/.h files per peripheral.

Step 4: Save the Configuration

• Press Ctrl + S to save the .ioc file, which will regenerate the code with the updated configuration.

Step 5: Add Flags for Float Support in printf and scanf

To enable floating-point support in printf and scanf, follow these steps:

1. Go to Project → Properties in STM32CubeIDE.
2. Navigate to C/C++ Build → Settings.
3. Under the Tool Settings tab, find Miscellaneous (under MCU GCC Linker).
4. In the Other Flags field, add the following flags:
   • -u _printf_float
   • -u _scanf_float
5. Click Apply and Close to save the changes.

This step ensures that floating-point values can be properly handled in formatted input/output functions like printf and scanf.

Step 6: Add the Required Files to Your Project

Add these files to your project:

• Place gps.c in the Core/Src folder.
• Place gps.h in the Core/Inc folder.

Step 7: Import the Library in main.c

1. Open main.c in STM32CubeIDE.
2. Add the following includes inside the /* USER CODE BEGIN Includes */ section:

/* Private includes ----------------------------------------------------------*/
/* USER CODE BEGIN Includes */
#include <stdio.h>
#include "string.h"
#include "gps.h"
/* USER CODE END Includes */

Step 8: Add GPS Setup Code

• In the /_ USER CODE BEGIN 2 _/ section of main.c, add the following setup code to initialize the BNO055 IMU sensor:

/* USER CODE BEGIN 2 */
GPS_Init();
/* USER CODE END 2 */

Step 9: Write a Function to Fetch and Transmit GPS Data

1. Inside the /_ USER CODE BEGIN 0 _/ section of main.c, add the following function:

/* Private user code ---------------------------------------------------------*/
/* USER CODE BEGIN 0 */
void HAL_UART_RxCpltCallback(UART_HandleTypeDef *huart)
{
	if(huart == GPS_USART) GPS_UART_CallBack();
}

void send_gps_data() {
	char buffer[200];

	// GPS data
	snprintf(buffer, sizeof(buffer),
			"[GPS Data] Time: %02d:%02d:%02d, Latitude: %.6f %c, Longitude: %.6f %c, Speed: %.2f knots, Status: %c\r\n",
			GPS.hours, GPS.minutes, GPS.seconds,  // Use pre-converted time
			GPS.dec_latitude,                     // Decimal latitude
			GPS.ns,                               // N/S indicator
			GPS.dec_longitude,                    // Decimal longitude
			GPS.ew,                               // E/W indicator
			GPS.speed_k,                          // Speed in knots
			GPS.rmc_status                        // RMC status ('A' = active, 'V' = void)
			);

	HAL_UART_Transmit(&huart3, (uint8_t*) buffer, strlen(buffer), HAL_MAX_DELAY);
	HAL_Delay(100); // 10 Hz
}
/* USER CODE END 0 */

2. Call the function inside the main loop to continuously fetch and transmit data:

/* Infinite loop */
/* USER CODE BEGIN WHILE */
while (1)
{
    /* USER CODE END WHILE */
    send_gps_data();
    /* USER CODE BEGIN 3 */
}
/* USER CODE END 3 */

Step 10: Circuit Connections

To connect the Adafruit Ultimate GPS HAT to the STM32 NUCLEO-H7A3ZI-Q, use the following wiring:

GPS HAT Pin	NUCLEO Pin
3.3V	3V3
GND	GND
TX	TX (PB6)
RX	RX (PB15)

Ensure the connections are secure to avoid communication issues. The image below illustrates the wiring:

For more detailed information about the external header connections of the NUCLEO-H7A3ZI-Q, refer to the image below:

For more detailed information about the external header connections of the Adafruit Ultimate GPS HAT, refer to the image below:

Tools

• IDE: STM32CubeIDE (1.16.1)
• Microcontroller: STM32 NUCLEO-H7A3ZI-Q
• GPS Module: Adafruit Ultimate GPS HAT for Raspberry Pi A+/B+/Pi 2/3/4/Pi 5 - Mini Kit

Third-Party Code

This project includes code from the gps.c and gps.h files by Bulanov Konstantin, originally sourced from the leech001/gps repository. The code is licensed under the GNU General Public License (GPL) v3.

For the full terms of the GPL, see the LICENSE file included in this repository.

Modifications

• Extended the GPS parsing logic to include additional NMEA messages:
  • $GNGGA: Position and satellite data
  • $GNRMC: Position, speed, and time data
• Added helper functions:
  • GPS_ConvertTime: Converts raw UTC time to hours, minutes, and seconds.
  • GPS_ConvertDate: Converts raw date to day, month, and year.