main.c File Reference

: Main program body More...

#include "main.h"
#include "sx1262.h"
#include "radio_app.h"
#include <sys/unistd.h>
#include <stdio.h>
#include <string.h>
#include "ada1897_mb85rs64b.h"
#include "qa_app.h"

Include dependency graph for main.c:

Functions
void	SystemClock_Config (void)
	Configure the MCU system clock.
int	_write (int file, char *ptr, int len)
	Retargets the C library write() function to UART1.
void	HAL_GPIO_EXTI_Callback (uint16_t pin)
	GPIO EXTI interrupt callback handler.
void	delay_us (uint16_t us)
	Busy-wait microsecond delay using TIM3.
int	main (void)
	Application entry point.
void	_Error_Handler (const char *file, int line)
	This function is executed in case of error occurrence.

Variables
CRYP_HandleTypeDef	hcryp
SPI_HandleTypeDef	hspi1
TIM_HandleTypeDef	htim3
UART_HandleTypeDef	huart1
SX1262_Handle	sx
SX1262_ROLE	sx1262Role

Detailed Description

: Main program body

Attention

Copyright (c) 2026 STMicroelectronics. All rights reserved.

This software is licensed under terms that can be found in the LICENSE file in the root directory of this software component. If no LICENSE file comes with this software, it is provided AS-IS.

Function Documentation

_Error_Handler()

void _Error_Handler	(	const char *	file,
		int	line )

This function is executed in case of error occurrence.

Parameters

file	The file name as string.
line	The line in file as a number.

_write()

int _write	(	int	file,
		char *	ptr,
		int	len )

Retargets the C library write() function to UART1.

This function allows standard library output functions such as printf() to transmit data over USART1. It is used by the newlib or nano-libc retargeting mechanism when stdout/stderr are mapped to this implementation.

The function calculates a bounded transmit timeout based on the number of bytes being written. This prevents large printf() calls from blocking the main loop for excessive periods of time.

Timeout estimation:

• 19200 baud, 8N1 ≈ 1.92 bytes/ms
• Approximate timeout = len / 2 ms
• Minimum timeout clamp: 10 ms
• Maximum timeout clamp: 300 ms

Parameters

file	File descriptor (unused).
ptr	Pointer to the buffer containing bytes to transmit.
len	Number of bytes to transmit.

Returns

Number of bytes successfully transmitted, or 0 on failure.

delay_us()

void delay_us

(

uint16_t

us

)

Busy-wait microsecond delay using TIM3.

This function provides a simple blocking delay with microsecond resolution by polling the TIM3 hardware counter. The timer must be configured so that its counter increments at 1 MHz (1 count per microsecond).

The function resets the TIM3 counter to zero and then spins until the counter reaches the requested delay value.

This delay mechanism is intended for short timing gaps required by hardware drivers (for example SPI peripherals, radio devices, or other timing-sensitive interfaces). Because it is a busy-wait loop, it will block the CPU for the duration of the delay and should not be used for long delays inside time-critical execution paths.

Parameters

us	Number of microseconds to delay.

HAL_GPIO_EXTI_Callback()

void HAL_GPIO_EXTI_Callback

(

uint16_t

pin

)

GPIO EXTI interrupt callback handler.

This function is invoked by the STM32 HAL whenever a GPIO external interrupt (EXTI) occurs. It serves as a bridge between the HAL interrupt infrastructure and the RadioApp layer.

For this project the callback is used to forward SX1262 DIO1 events to the radio application logic, allowing the RadioApp layer to process radio interrupts without embedding radio logic inside CubeMX-generated code.

Parameters

pin	GPIO pin number that triggered the EXTI interrupt.

main()

int main

(

void

)

Application entry point.

Initializes the HAL, configures the system clock, initializes all CubeMX-generated peripherals, and then performs application specific initialization for the LoRa radio stack and FRAM persistence layer.

After initialization completes the firmware enters the main service loop where RadioApp_Loop() drives the radio state machine.

Return values

int	Should never return.

SystemClock_Config()

void SystemClock_Config

(

void

)

Configure the MCU system clock.

Configures PLL and bus clocks generated by STM32CubeMX. This function is generated by CubeMX and should not be modified outside USER CODE blocks.

Any failure in clock configuration results in Error_Handler().

Configure the main internal regulator output voltage

Initializes the RCC Oscillators according to the specified parameters in the RCC_OscInitTypeDef structure.

Activate the Over-Drive mode

Initializes the CPU, AHB and APB buses clocks

Variable Documentation

hcryp

CRYP_HandleTypeDef hcryp

hspi1

SPI_HandleTypeDef hspi1

htim3

TIM_HandleTypeDef htim3

huart1

UART_HandleTypeDef huart1

sx

SX1262_Handle sx

sx1262Role

SX1262_ROLE sx1262Role