Getting started with STM32F407 and STM32CubeIDE
- Thread starter MrChips
- Start date
- Status
To get started, you will need these three essential documents:
STM32F4-DISCO User Manual UM1472
STM32F407 Datasheet
STM32F407 Reference Manual RM0090
STM32F4-DISCO User Manual UM1472
STM32F407 Datasheet
STM32F407 Reference Manual RM0090
The first thing we will attempt to do is make one of the LEDs blink, the quintessential "blinky" project.
Look up the STM32F4-DISCO documentation and find LED pin assignments.
LD3 = PD13 = orange
LD4 = PD12 = green
LD5 = PD14 = red
LD6 = PD15 = blue
We will make the green LED (PD12) flash.
Start up STM32CubeIDE.
Start new STM32 project.
Choose the board = STM32F4-Discovery
In the Project panel, look for Src>main.c
Here is the main.c code template automatically generated by STM32CubeIDE:
Look up the STM32F4-DISCO documentation and find LED pin assignments.
LD3 = PD13 = orange
LD4 = PD12 = green
LD5 = PD14 = red
LD6 = PD15 = blue
We will make the green LED (PD12) flash.
Start up STM32CubeIDE.
Start new STM32 project.
Choose the board = STM32F4-Discovery
In the Project panel, look for Src>main.c
Here is the main.c code template automatically generated by STM32CubeIDE:
C:
/* USER CODE BEGIN Header */
/**
******************************************************************************
* @file : main.c
* @brief : Main program body
******************************************************************************
* @attention
*
* <h2><center>© Copyright (c) 2019 STMicroelectronics.
* All rights reserved.</center></h2>
*
* This software component is licensed by ST under Ultimate Liberty license
* SLA0044, the "License"; You may not use this file except in compliance with
* the License. You may obtain a copy of the License at:
* www.st.com/SLA0044
*
******************************************************************************
*/
/* USER CODE END Header */
/* Includes ----------------------*/
#include "main.h"
#include "usb_host.h"
/* Private includes ---------------*/
/* USER CODE BEGIN Includes */
/* USER CODE END Includes */
/* Private typedef --------------------*/
/* USER CODE BEGIN PTD */
/* USER CODE END PTD */
/* Private define -----------------------*/
/* USER CODE BEGIN PD */
/* USER CODE END PD */
/* Private macro -----------------------*/
/* USER CODE BEGIN PM */
/* USER CODE END PM */
/* Private variables ---------------------*/
I2C_HandleTypeDef hi2c1;
I2S_HandleTypeDef hi2s3;
SPI_HandleTypeDef hspi1;
/* USER CODE BEGIN PV */
/* USER CODE END PV */
/* Private function prototypes --------------*/
void SystemClock_Config(void);
static void MX_GPIO_Init(void);
static void MX_I2C1_Init(void);
static void MX_I2S3_Init(void);
static void MX_SPI1_Init(void);
void MX_USB_HOST_Process(void);
/* USER CODE BEGIN PFP */
/* USER CODE END PFP */
/* Private user code --------------------------*/
/* USER CODE BEGIN 0 */
/* USER CODE END 0 */
/**
* @brief The application entry point.
* @retval int
*/
int main(void)
{
/* USER CODE BEGIN 1 */
/* USER CODE END 1 */
/* MCU Configuration---------------------------*/
/* Reset of all peripherals, Initializes the Flash interface and the Systick. */
HAL_Init();
/* USER CODE BEGIN Init */
/* USER CODE END Init */
/* Configure the system clock */
SystemClock_Config();
/* USER CODE BEGIN SysInit */
/* USER CODE END SysInit */
/* Initialize all configured peripherals */
MX_GPIO_Init();
MX_I2C1_Init();
MX_I2S3_Init();
MX_SPI1_Init();
MX_USB_HOST_Init();
/* USER CODE BEGIN 2 */
/* USER CODE END 2 */
/* Infinite loop */
/* USER CODE BEGIN WHILE */
while (1)
{
/* USER CODE END WHILE */
MX_USB_HOST_Process();
/* USER CODE BEGIN 3 */
}
/* USER CODE END 3 */
}
/**
* @brief System Clock Configuration
* @retval None
*/
void SystemClock_Config(void)
{
RCC_OscInitTypeDef RCC_OscInitStruct = {0};
RCC_ClkInitTypeDef RCC_ClkInitStruct = {0};
RCC_PeriphCLKInitTypeDef PeriphClkInitStruct = {0};
/** Configure the main internal regulator output voltage
*/
__HAL_RCC_PWR_CLK_ENABLE();
__HAL_PWR_VOLTAGESCALING_CONFIG(PWR_REGULATOR_VOLTAGE_SCALE1);
/** Initializes the CPU, AHB and APB busses clocks
*/
RCC_OscInitStruct.OscillatorType = RCC_OSCILLATORTYPE_HSE;
RCC_OscInitStruct.HSEState = RCC_HSE_ON;
RCC_OscInitStruct.PLL.PLLState = RCC_PLL_ON;
RCC_OscInitStruct.PLL.PLLSource = RCC_PLLSOURCE_HSE;
RCC_OscInitStruct.PLL.PLLM = 8;
RCC_OscInitStruct.PLL.PLLN = 336;
RCC_OscInitStruct.PLL.PLLP = RCC_PLLP_DIV2;
RCC_OscInitStruct.PLL.PLLQ = 7;
if (HAL_RCC_OscConfig(&RCC_OscInitStruct) != HAL_OK)
{
Error_Handler();
}
/** Initializes the CPU, AHB and APB busses clocks
*/
RCC_ClkInitStruct.ClockType = RCC_CLOCKTYPE_HCLK|RCC_CLOCKTYPE_SYSCLK
|RCC_CLOCKTYPE_PCLK1|RCC_CLOCKTYPE_PCLK2;
RCC_ClkInitStruct.SYSCLKSource = RCC_SYSCLKSOURCE_PLLCLK;
RCC_ClkInitStruct.AHBCLKDivider = RCC_SYSCLK_DIV1;
RCC_ClkInitStruct.APB1CLKDivider = RCC_HCLK_DIV4;
RCC_ClkInitStruct.APB2CLKDivider = RCC_HCLK_DIV2;
if (HAL_RCC_ClockConfig(&RCC_ClkInitStruct, FLASH_LATENCY_5) != HAL_OK)
{
Error_Handler();
}
PeriphClkInitStruct.PeriphClockSelection = RCC_PERIPHCLK_I2S;
PeriphClkInitStruct.PLLI2S.PLLI2SN = 192;
PeriphClkInitStruct.PLLI2S.PLLI2SR = 2;
if (HAL_RCCEx_PeriphCLKConfig(&PeriphClkInitStruct) != HAL_OK)
{
Error_Handler();
}
}
/**
* @brief I2C1 Initialization Function
* @param None
* @retval None
*/
static void MX_I2C1_Init(void)
{
/* USER CODE BEGIN I2C1_Init 0 */
/* USER CODE END I2C1_Init 0 */
/* USER CODE BEGIN I2C1_Init 1 */
/* USER CODE END I2C1_Init 1 */
hi2c1.Instance = I2C1;
hi2c1.Init.ClockSpeed = 100000;
hi2c1.Init.DutyCycle = I2C_DUTYCYCLE_2;
hi2c1.Init.OwnAddress1 = 0;
hi2c1.Init.AddressingMode = I2C_ADDRESSINGMODE_7BIT;
hi2c1.Init.DualAddressMode = I2C_DUALADDRESS_DISABLE;
hi2c1.Init.OwnAddress2 = 0;
hi2c1.Init.GeneralCallMode = I2C_GENERALCALL_DISABLE;
hi2c1.Init.NoStretchMode = I2C_NOSTRETCH_DISABLE;
if (HAL_I2C_Init(&hi2c1) != HAL_OK)
{
Error_Handler();
}
/* USER CODE BEGIN I2C1_Init 2 */
/* USER CODE END I2C1_Init 2 */
}
/**
* @brief I2S3 Initialization Function
* @param None
* @retval None
*/
static void MX_I2S3_Init(void)
{
/* USER CODE BEGIN I2S3_Init 0 */
/* USER CODE END I2S3_Init 0 */
/* USER CODE BEGIN I2S3_Init 1 */
/* USER CODE END I2S3_Init 1 */
hi2s3.Instance = SPI3;
hi2s3.Init.Mode = I2S_MODE_MASTER_TX;
hi2s3.Init.Standard = I2S_STANDARD_PHILIPS;
hi2s3.Init.DataFormat = I2S_DATAFORMAT_16B;
hi2s3.Init.MCLKOutput = I2S_MCLKOUTPUT_ENABLE;
hi2s3.Init.AudioFreq = I2S_AUDIOFREQ_96K;
hi2s3.Init.CPOL = I2S_CPOL_LOW;
hi2s3.Init.ClockSource = I2S_CLOCK_PLL;
hi2s3.Init.FullDuplexMode = I2S_FULLDUPLEXMODE_DISABLE;
if (HAL_I2S_Init(&hi2s3) != HAL_OK)
{
Error_Handler();
}
/* USER CODE BEGIN I2S3_Init 2 */
/* USER CODE END I2S3_Init 2 */
}
/**
* @brief SPI1 Initialization Function
* @param None
* @retval None
*/
static void MX_SPI1_Init(void)
{
/* USER CODE BEGIN SPI1_Init 0 */
/* USER CODE END SPI1_Init 0 */
/* USER CODE BEGIN SPI1_Init 1 */
/* USER CODE END SPI1_Init 1 */
/* SPI1 parameter configuration*/
hspi1.Instance = SPI1;
hspi1.Init.Mode = SPI_MODE_MASTER;
hspi1.Init.Direction = SPI_DIRECTION_2LINES;
hspi1.Init.DataSize = SPI_DATASIZE_8BIT;
hspi1.Init.CLKPolarity = SPI_POLARITY_LOW;
hspi1.Init.CLKPhase = SPI_PHASE_1EDGE;
hspi1.Init.NSS = SPI_NSS_SOFT;
hspi1.Init.BaudRatePrescaler = SPI_BAUDRATEPRESCALER_2;
hspi1.Init.FirstBit = SPI_FIRSTBIT_MSB;
hspi1.Init.TIMode = SPI_TIMODE_DISABLE;
hspi1.Init.CRCCalculation = SPI_CRCCALCULATION_DISABLE;
hspi1.Init.CRCPolynomial = 10;
if (HAL_SPI_Init(&hspi1) != HAL_OK)
{
Error_Handler();
}
/* USER CODE BEGIN SPI1_Init 2 */
/* USER CODE END SPI1_Init 2 */
}
/**
* @brief GPIO Initialization Function
* @param None
* @retval None
*/
static void MX_GPIO_Init(void)
{
GPIO_InitTypeDef GPIO_InitStruct = {0};
/* GPIO Ports Clock Enable */
__HAL_RCC_GPIOE_CLK_ENABLE();
__HAL_RCC_GPIOC_CLK_ENABLE();
__HAL_RCC_GPIOH_CLK_ENABLE();
__HAL_RCC_GPIOA_CLK_ENABLE();
__HAL_RCC_GPIOB_CLK_ENABLE();
__HAL_RCC_GPIOD_CLK_ENABLE();
/*Configure GPIO pin Output Level */
HAL_GPIO_WritePin(CS_I2C_SPI_GPIO_Port, CS_I2C_SPI_Pin, GPIO_PIN_RESET);
/*Configure GPIO pin Output Level */
HAL_GPIO_WritePin(OTG_FS_PowerSwitchOn_GPIO_Port, OTG_FS_PowerSwitchOn_Pin, GPIO_PIN_SET);
/*Configure GPIO pin Output Level */
HAL_GPIO_WritePin(GPIOD, LD4_Pin|LD3_Pin|LD5_Pin|LD6_Pin
|Audio_RST_Pin, GPIO_PIN_RESET);
/*Configure GPIO pin : CS_I2C_SPI_Pin */
GPIO_InitStruct.Pin = CS_I2C_SPI_Pin;
GPIO_InitStruct.Mode = GPIO_MODE_OUTPUT_PP;
GPIO_InitStruct.Pull = GPIO_NOPULL;
GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_LOW;
HAL_GPIO_Init(CS_I2C_SPI_GPIO_Port, &GPIO_InitStruct);
/*Configure GPIO pin : OTG_FS_PowerSwitchOn_Pin */
GPIO_InitStruct.Pin = OTG_FS_PowerSwitchOn_Pin;
GPIO_InitStruct.Mode = GPIO_MODE_OUTPUT_PP;
GPIO_InitStruct.Pull = GPIO_NOPULL;
GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_LOW;
HAL_GPIO_Init(OTG_FS_PowerSwitchOn_GPIO_Port, &GPIO_InitStruct);
/*Configure GPIO pin : PDM_OUT_Pin */
GPIO_InitStruct.Pin = PDM_OUT_Pin;
GPIO_InitStruct.Mode = GPIO_MODE_AF_PP;
GPIO_InitStruct.Pull = GPIO_NOPULL;
GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_LOW;
GPIO_InitStruct.Alternate = GPIO_AF5_SPI2;
HAL_GPIO_Init(PDM_OUT_GPIO_Port, &GPIO_InitStruct);
/*Configure GPIO pin : B1_Pin */
GPIO_InitStruct.Pin = B1_Pin;
GPIO_InitStruct.Mode = GPIO_MODE_EVT_RISING;
GPIO_InitStruct.Pull = GPIO_NOPULL;
HAL_GPIO_Init(B1_GPIO_Port, &GPIO_InitStruct);
/*Configure GPIO pin : BOOT1_Pin */
GPIO_InitStruct.Pin = BOOT1_Pin;
GPIO_InitStruct.Mode = GPIO_MODE_INPUT;
GPIO_InitStruct.Pull = GPIO_NOPULL;
HAL_GPIO_Init(BOOT1_GPIO_Port, &GPIO_InitStruct);
/*Configure GPIO pin : CLK_IN_Pin */
GPIO_InitStruct.Pin = CLK_IN_Pin;
GPIO_InitStruct.Mode = GPIO_MODE_AF_PP;
GPIO_InitStruct.Pull = GPIO_NOPULL;
GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_LOW;
GPIO_InitStruct.Alternate = GPIO_AF5_SPI2;
HAL_GPIO_Init(CLK_IN_GPIO_Port, &GPIO_InitStruct);
/*Configure GPIO pins : LD4_Pin LD3_Pin LD5_Pin LD6_Pin
Audio_RST_Pin */
GPIO_InitStruct.Pin = LD4_Pin|LD3_Pin|LD5_Pin|LD6_Pin
|Audio_RST_Pin;
GPIO_InitStruct.Mode = GPIO_MODE_OUTPUT_PP;
GPIO_InitStruct.Pull = GPIO_NOPULL;
GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_LOW;
HAL_GPIO_Init(GPIOD, &GPIO_InitStruct);
/*Configure GPIO pin : OTG_FS_OverCurrent_Pin */
GPIO_InitStruct.Pin = OTG_FS_OverCurrent_Pin;
GPIO_InitStruct.Mode = GPIO_MODE_INPUT;
GPIO_InitStruct.Pull = GPIO_NOPULL;
HAL_GPIO_Init(OTG_FS_OverCurrent_GPIO_Port, &GPIO_InitStruct);
/*Configure GPIO pin : MEMS_INT2_Pin */
GPIO_InitStruct.Pin = MEMS_INT2_Pin;
GPIO_InitStruct.Mode = GPIO_MODE_EVT_RISING;
GPIO_InitStruct.Pull = GPIO_NOPULL;
HAL_GPIO_Init(MEMS_INT2_GPIO_Port, &GPIO_InitStruct);
}
/* USER CODE BEGIN 4 */
/* USER CODE END 4 */
/**
* @brief This function is executed in case of error occurrence.
* @retval None
*/
void Error_Handler(void)
{
/* USER CODE BEGIN Error_Handler_Debug */
/* User can add his own implementation to report the HAL error return state */
/* USER CODE END Error_Handler_Debug */
}
#ifdef USE_FULL_ASSERT
/**
* @brief Reports the name of the source file and the source line number
* where the assert_param error has occurred.
* @param file: pointer to the source file name
* @param line: assert_param error line source number
* @retval None
*/
void assert_failed(uint8_t *file, uint32_t line)
{
/* USER CODE BEGIN 6 */
/* User can add his own implementation to report the file name and line number,
tex: printf("Wrong parameters value: file %s on line %d\r\n", file, line) */
/* USER CODE END 6 */
}
#endif /* USE_FULL_ASSERT */
/************************ (C) COPYRIGHT STMicroelectronics *****END OF FILE****/The next step is to connect the STM32F4-DISCO board to a USB port using the USB cable supplied.
Click on Debug icon (or press F11 under the Run menu).
This will compile the program, build the project, and transfer the binary code to the STM32F407 MCU chip.
There will be nothing to see at this point. We will add the "blinky" code in the next step.
Click on Debug icon (or press F11 under the Run menu).
This will compile the program, build the project, and transfer the binary code to the STM32F407 MCU chip.
There will be nothing to see at this point. We will add the "blinky" code in the next step.
The purpose of the above exercise is to ensure that the STM32CubeIDE is properly installed and the ST-LINK downloader utility is up and running.
Now we will add the "blinky" code.
80% of the prewritten program is not needed at this point. However, some time in the future we will need this hardware initialization code. Hence it is best to leave it in place and we can pick it apart later.
In main.c, find the endless while (1) loop. (See Line 111 in the code in post #4.)
Note that I commented out Line 124.
We will add two lines of code, one to toggle the green LED on PD12, and another to delay 250ms.
Run your revised program and watch the green LED flash once every 500ms.
Congratulations!
You have your first STM32CubeIDE project running on your STM32F4-DISCO.
Now we will add the "blinky" code.
80% of the prewritten program is not needed at this point. However, some time in the future we will need this hardware initialization code. Hence it is best to leave it in place and we can pick it apart later.
In main.c, find the endless while (1) loop. (See Line 111 in the code in post #4.)
Note that I commented out Line 124.
We will add two lines of code, one to toggle the green LED on PD12, and another to delay 250ms.
C:
/* Infinite loop */
/* USER CODE BEGIN WHILE */
while (1)
{
/* USER CODE END WHILE */
//MX_USB_HOST_Process();
HAL_GPIO_TogglePin(GPIOD, GPIO_PIN_12);
HAL_Delay(250);
/* USER CODE BEGIN 3 */
}
/* USER CODE END 3 */Congratulations!
You have your first STM32CubeIDE project running on your STM32F4-DISCO.
i had this thread https://forum.allaboutcircuits.com/threads/event-counter-stm32f407.159894/
okay I would like to continue this thread here
How to make a counter using timer 2?
okay I would like to continue this thread here
How to make a counter using timer 2?
TIMERS and GPIO Output
By popular request, I am going to show how to use a timer module to generate output on a GPIO pin.
Let us assume that we wish to generate digital pulses on a GPIO pin, specifically PD12 which is connected to the green LED (LD4) on the STM32F4-DISCO board.
The first thing that needs to be done is to make sure that you can program the board to toggle PD12 (see above). This tests the operation of the STM32CubeIDE and that your board and code is functional.
The next step is to select a timer module. Which timer should you choose?
To answer this question you need to look at which timers are mapped to which GPIO pins. For this, you need to look at STM32F407 Datasheet.
Table 9 on page 65 shows that PD12 is connected to TIM4_CH1 as an alternate function AF2.
Hence we need to select timer module TIM4.
By popular request, I am going to show how to use a timer module to generate output on a GPIO pin.
Let us assume that we wish to generate digital pulses on a GPIO pin, specifically PD12 which is connected to the green LED (LD4) on the STM32F4-DISCO board.
The first thing that needs to be done is to make sure that you can program the board to toggle PD12 (see above). This tests the operation of the STM32CubeIDE and that your board and code is functional.
The next step is to select a timer module. Which timer should you choose?
To answer this question you need to look at which timers are mapped to which GPIO pins. For this, you need to look at STM32F407 Datasheet.
Table 9 on page 65 shows that PD12 is connected to TIM4_CH1 as an alternate function AF2.
Hence we need to select timer module TIM4.
Once we have verified that STM32CubeIDE is up and running and we are able to make an LED blink we can move on to a timer example using TIM4.
Invariably, when writing and debugging code using a timer module it helps greatly to have an oscilloscope otherwise you are just shooting in the dark. However, if you do not have an oscilloscope you should still be able to get it working if you follow the instructions below.
The first thing we need to do is configure the hardware using the Device Configuration Tool, [MX] icon in the upper-right corner of the CubeIDE window.
Next, we go to PD12 pin and select TIM4_CH1 option.
PD12 is now wired to TIM4_CH1 output or will be when the code is executed.
Now we go and set up TIM4 timer module.
Invariably, when writing and debugging code using a timer module it helps greatly to have an oscilloscope otherwise you are just shooting in the dark. However, if you do not have an oscilloscope you should still be able to get it working if you follow the instructions below.
The first thing we need to do is configure the hardware using the Device Configuration Tool, [MX] icon in the upper-right corner of the CubeIDE window.
Next, we go to PD12 pin and select TIM4_CH1 option.
PD12 is now wired to TIM4_CH1 output or will be when the code is executed.
Now we go and set up TIM4 timer module.
The next step is configuring the TIM4 timer module. Here is where the fun begins.
Timer modules on microprocessors are incredibly useful things and come with numerous functions. In the simplest mode you can simply use it to count external events in order to measure frequency. Inversely, you can clock the counter with an internal clock and use it to measure period or time intervals.
Timer modules can also be used to generate square waves, rectangular waves, single pulses, PWM waveforms, and analog waveforms. Two important timer modes are input capture mode and output compare mode. In this example, we will be using the output compare mode.
Note that all of the above functions are performed entirely within the timer module hardware and do not require software intervention besides configuration, initialization, and starting the counter. Software can be invoked at a critical moment (called an update event) by having the hardware trigger an interrupt. Furthermore, MCU systems that allow DMA (direct memory access) capability can cause other hardware modules to be triggered such as ADC, DAC, UART/USART, SPI, I2C, etc. so that complex functions can be created with no software intervention required. I have used STM32F407 timers to generate VGA graphics entirely from hardware with zero CPU cycles used.
OUTPUT COMPARE
How does output compare operate?
I will describe output compare mode using register names as defined by the STM32 architecture.
I will discuss three important registers:
CNT - counter register, 16-bit or 32-bit register (TIM4_CNT is 16 bits long)
ARR - auto-reload register
CCR1 - capture-compare register (channel 1)
In essence, there is a counter register called CNT. Very simply, this register is incremented or decremented on each clock input. This register simply does its thing and you can just about forget about it.
The ARR (auto-reload register) is more important. This sets the maximum count value of CNT. Set ARR to any value from 1 to 65535 (for 16-bit timers) and the counter will count up to this value and automatically reset to 0.
The next import register is the capture-compare register CCRn. There are four such registers CCR1-CCR4 and for this example we will be focusing on CCR1 (i.e. channel 1). Remember, we are going to use TIM4_CH1.
How does this work?
Set CCR1 to any value between 0 and the ARR value. When the CNT value matches the CCR1 value an update event is triggered.
What can we do with update event?
We have a number of possibilities here. For this example, we will choose the simplest mode, i.e. Toggle on match.
This means that every time CNT matches CCR1 we will toggle the output channel which is connected to PD12.
That's it. We're done.
What is the frequency of the output signal?
The toggle rate will depend on a number of different parameters. For this reason I cannot tell you how to set up TIM4 to give an exact period of 1 second. This is something you will have to work out on your own. (I can only show you what values I have used and what period I measured after viewing the pulse output on the oscilloscope.) The period will depend on the following parameters:
1) The timer clock source
2) The internal clock frequency if you are going to configure TIM4 to use the internal clock
3) The internal clock frequency will depend on the system clock frequency and the divider settings used in the system clock dividers
4) TIM4_PSC (prescaler). The TIM4 input clock frequency will be divided by (PSC + 1).
5) TIM4_ARR value
TIM4_CCR1 has no effect in this example. You can set TIM4_CCR1 = 0 so that TIM4 will always trigger an update event when TIM4_CNT equals 0.
Timer modules on microprocessors are incredibly useful things and come with numerous functions. In the simplest mode you can simply use it to count external events in order to measure frequency. Inversely, you can clock the counter with an internal clock and use it to measure period or time intervals.
Timer modules can also be used to generate square waves, rectangular waves, single pulses, PWM waveforms, and analog waveforms. Two important timer modes are input capture mode and output compare mode. In this example, we will be using the output compare mode.
Note that all of the above functions are performed entirely within the timer module hardware and do not require software intervention besides configuration, initialization, and starting the counter. Software can be invoked at a critical moment (called an update event) by having the hardware trigger an interrupt. Furthermore, MCU systems that allow DMA (direct memory access) capability can cause other hardware modules to be triggered such as ADC, DAC, UART/USART, SPI, I2C, etc. so that complex functions can be created with no software intervention required. I have used STM32F407 timers to generate VGA graphics entirely from hardware with zero CPU cycles used.
OUTPUT COMPARE
How does output compare operate?
I will describe output compare mode using register names as defined by the STM32 architecture.
I will discuss three important registers:
CNT - counter register, 16-bit or 32-bit register (TIM4_CNT is 16 bits long)
ARR - auto-reload register
CCR1 - capture-compare register (channel 1)
In essence, there is a counter register called CNT. Very simply, this register is incremented or decremented on each clock input. This register simply does its thing and you can just about forget about it.
The ARR (auto-reload register) is more important. This sets the maximum count value of CNT. Set ARR to any value from 1 to 65535 (for 16-bit timers) and the counter will count up to this value and automatically reset to 0.
The next import register is the capture-compare register CCRn. There are four such registers CCR1-CCR4 and for this example we will be focusing on CCR1 (i.e. channel 1). Remember, we are going to use TIM4_CH1.
How does this work?
Set CCR1 to any value between 0 and the ARR value. When the CNT value matches the CCR1 value an update event is triggered.
What can we do with update event?
We have a number of possibilities here. For this example, we will choose the simplest mode, i.e. Toggle on match.
This means that every time CNT matches CCR1 we will toggle the output channel which is connected to PD12.
That's it. We're done.
What is the frequency of the output signal?
The toggle rate will depend on a number of different parameters. For this reason I cannot tell you how to set up TIM4 to give an exact period of 1 second. This is something you will have to work out on your own. (I can only show you what values I have used and what period I measured after viewing the pulse output on the oscilloscope.) The period will depend on the following parameters:
1) The timer clock source
2) The internal clock frequency if you are going to configure TIM4 to use the internal clock
3) The internal clock frequency will depend on the system clock frequency and the divider settings used in the system clock dividers
4) TIM4_PSC (prescaler). The TIM4 input clock frequency will be divided by (PSC + 1).
5) TIM4_ARR value
TIM4_CCR1 has no effect in this example. You can set TIM4_CCR1 = 0 so that TIM4 will always trigger an update event when TIM4_CNT equals 0.
Now that you have some understanding of how PD12 will be toggled by TIM4_CH1 output compare update event, let us configure the TIM4 module. Go through the TIM4 Mode and Configuration dialog and examine each setting. In particular, we want to set the following:
Mode
Clock Source: Internal Clock
Channel1: Output Compare CH1
Configuration
Parameter Settings
Prescaler (PSC): 0
Counter Period (ARR): 1
Output Compare Channel 1
Mode: Toggle on match
I have selected the above parameters for testing on an oscilloscope. We will modify these values later.
After the Mode and Configuration is set, click on the Device Configuration Tool Code Generation icon.
This will take some time to process. Be patient.
This will generate the required configuration and initialization code.
Tip: Generated code will replace any previously written code. If you wish to add your own code, make sure that you place your code in between two comment lines given:
/* USER CODE BEGIN ...*/
... your code
/* USER CODE END ... */
Code main.c is found in the project tree Core>Scr. Look in main.c and examine the code generated for MX_TIM4_Init(void).
Before we run this generated code, we need to add two lines.
Here is code as generated with two lines added at lines 204 and 205.
Edit: The line numbers are different depending on how it is rendered by the browser when long lines are wrapped around.
These are the instructions added.
TIM_CCxChannelCmd(TIM4, TIM_CHANNEL_1, TIM_CCx_ENABLE);
__HAL_TIM_ENABLE(&htim4);
Mode
Clock Source: Internal Clock
Channel1: Output Compare CH1
Configuration
Parameter Settings
Prescaler (PSC): 0
Counter Period (ARR): 1
Output Compare Channel 1
Mode: Toggle on match
I have selected the above parameters for testing on an oscilloscope. We will modify these values later.
After the Mode and Configuration is set, click on the Device Configuration Tool Code Generation icon.
This will take some time to process. Be patient.
This will generate the required configuration and initialization code.
Tip: Generated code will replace any previously written code. If you wish to add your own code, make sure that you place your code in between two comment lines given:
/* USER CODE BEGIN ...*/
... your code
/* USER CODE END ... */
Code main.c is found in the project tree Core>Scr. Look in main.c and examine the code generated for MX_TIM4_Init(void).
Before we run this generated code, we need to add two lines.
Here is code as generated with two lines added at lines 204 and 205.
Edit: The line numbers are different depending on how it is rendered by the browser when long lines are wrapped around.
These are the instructions added.
TIM_CCxChannelCmd(TIM4, TIM_CHANNEL_1, TIM_CCx_ENABLE);
__HAL_TIM_ENABLE(&htim4);
C:
/* USER CODE BEGIN Header */
/**
******************************************************************************
* @file : main.c
* @brief : Main program body
******************************************************************************
* @attention
*
* <h2><center>© Copyright (c) 2020 STMicroelectronics.
* All rights reserved.</center></h2>
*
* This software component is licensed by ST under BSD 3-Clause license,
* the "License"; You may not use this file except in compliance with the
* License. You may obtain a copy of the License at:
* opensource.org/licenses/BSD-3-Clause
*
******************************************************************************
*/
/* USER CODE END Header */
/* Includes -----------------------------------*/
#include "main.h"
/* Private includes ----------------------------*/
/* USER CODE BEGIN Includes */
/* USER CODE END Includes */
/* Private typedef ------------------------------*/
/* USER CODE BEGIN PTD */
/* USER CODE END PTD */
/* Private define --------------------------------*/
/* USER CODE BEGIN PD */
/* USER CODE END PD */
/* Private macro ---------------------------------*/
/* USER CODE BEGIN PM */
/* USER CODE END PM */
/* Private variables -------------------------------*/
TIM_HandleTypeDef htim4;
/* USER CODE BEGIN PV */
/* USER CODE END PV */
/* Private function prototypes ---------------------*/
void SystemClock_Config(void);
static void MX_GPIO_Init(void);
static void MX_TIM4_Init(void);
/* USER CODE BEGIN PFP */
/* USER CODE END PFP */
/* Private user code --------------------------------*/
/* USER CODE BEGIN 0 */
/* USER CODE END 0 */
/**
* @brief The application entry point.
* @retval int
*/
int main(void)
{
/* USER CODE BEGIN 1 */
/* USER CODE END 1 */
/* MCU Configuration-------------------------*/
/* Reset of all peripherals, Initializes the Flash interface and the Systick. */
HAL_Init();
/* USER CODE BEGIN Init */
/* USER CODE END Init */
/* Configure the system clock */
SystemClock_Config();
/* USER CODE BEGIN SysInit */
/* USER CODE END SysInit */
/* Initialize all configured peripherals */
MX_GPIO_Init();
MX_TIM4_Init();
/* USER CODE BEGIN 2 */
/* USER CODE END 2 */
/* Infinite loop */
/* USER CODE BEGIN WHILE */
while (1)
{
/* USER CODE END WHILE */
/* USER CODE BEGIN 3 */
}
/* USER CODE END 3 */
}
/**
* @brief System Clock Configuration
* @retval None
*/
void SystemClock_Config(void)
{
RCC_OscInitTypeDef RCC_OscInitStruct = {0};
RCC_ClkInitTypeDef RCC_ClkInitStruct = {0};
/** Configure the main internal regulator output voltage
*/
__HAL_RCC_PWR_CLK_ENABLE();
__HAL_PWR_VOLTAGESCALING_CONFIG(PWR_REGULATOR_VOLTAGE_SCALE1);
/** Initializes the RCC Oscillators according to the specified parameters
* in the RCC_OscInitTypeDef structure.
*/
RCC_OscInitStruct.OscillatorType = RCC_OSCILLATORTYPE_HSI;
RCC_OscInitStruct.HSIState = RCC_HSI_ON;
RCC_OscInitStruct.HSICalibrationValue = RCC_HSICALIBRATION_DEFAULT;
RCC_OscInitStruct.PLL.PLLState = RCC_PLL_ON;
RCC_OscInitStruct.PLL.PLLSource = RCC_PLLSOURCE_HSI;
RCC_OscInitStruct.PLL.PLLM = 8;
RCC_OscInitStruct.PLL.PLLN = 50;
RCC_OscInitStruct.PLL.PLLP = RCC_PLLP_DIV4;
RCC_OscInitStruct.PLL.PLLQ = 7;
if (HAL_RCC_OscConfig(&RCC_OscInitStruct) != HAL_OK)
{
Error_Handler();
}
/** Initializes the CPU, AHB and APB buses clocks
*/
RCC_ClkInitStruct.ClockType = RCC_CLOCKTYPE_HCLK|RCC_CLOCKTYPE_SYSCLK
|RCC_CLOCKTYPE_PCLK1|RCC_CLOCKTYPE_PCLK2;
RCC_ClkInitStruct.SYSCLKSource = RCC_SYSCLKSOURCE_PLLCLK;
RCC_ClkInitStruct.AHBCLKDivider = RCC_SYSCLK_DIV1;
RCC_ClkInitStruct.APB1CLKDivider = RCC_HCLK_DIV4;
RCC_ClkInitStruct.APB2CLKDivider = RCC_HCLK_DIV2;
if (HAL_RCC_ClockConfig(&RCC_ClkInitStruct, FLASH_LATENCY_0) != HAL_OK)
{
Error_Handler();
}
}
/**
* @brief TIM4 Initialization Function
* @param None
* @retval None
*/
static void MX_TIM4_Init(void)
{
/* USER CODE BEGIN TIM4_Init 0 */
/* USER CODE END TIM4_Init 0 */
TIM_ClockConfigTypeDef sClockSourceConfig = {0};
TIM_MasterConfigTypeDef sMasterConfig = {0};
TIM_OC_InitTypeDef sConfigOC = {0};
/* USER CODE BEGIN TIM4_Init 1 */
/* USER CODE END TIM4_Init 1 */
htim4.Instance = TIM4;
htim4.Init.Prescaler = 0;
htim4.Init.CounterMode = TIM_COUNTERMODE_UP;
htim4.Init.Period = 1;
htim4.Init.ClockDivision = TIM_CLOCKDIVISION_DIV1;
htim4.Init.AutoReloadPreload = TIM_AUTORELOAD_PRELOAD_DISABLE;
if (HAL_TIM_Base_Init(&htim4) != HAL_OK)
{
Error_Handler();
}
sClockSourceConfig.ClockSource = TIM_CLOCKSOURCE_INTERNAL;
if (HAL_TIM_ConfigClockSource(&htim4, &sClockSourceConfig) != HAL_OK)
{
Error_Handler();
}
if (HAL_TIM_OC_Init(&htim4) != HAL_OK)
{
Error_Handler();
}
sMasterConfig.MasterOutputTrigger = TIM_TRGO_RESET;
sMasterConfig.MasterSlaveMode = TIM_MASTERSLAVEMODE_DISABLE;
if (HAL_TIMEx_MasterConfigSynchronization(&htim4, &sMasterConfig) != HAL_OK)
{
Error_Handler();
}
sConfigOC.OCMode = TIM_OCMODE_TOGGLE;
sConfigOC.Pulse = 0;
sConfigOC.OCPolarity = TIM_OCPOLARITY_HIGH;
sConfigOC.OCFastMode = TIM_OCFAST_DISABLE;
if (HAL_TIM_OC_ConfigChannel(&htim4, &sConfigOC, TIM_CHANNEL_1) != HAL_OK)
{
Error_Handler();
}
__HAL_TIM_ENABLE_OCxPRELOAD(&htim4, TIM_CHANNEL_1);
/* USER CODE BEGIN TIM4_Init 2 */
TIM_CCxChannelCmd(TIM4, TIM_CHANNEL_1, TIM_CCx_ENABLE);
__HAL_TIM_ENABLE(&htim4);
/* USER CODE END TIM4_Init 2 */
HAL_TIM_MspPostInit(&htim4);
}
/**
* @brief GPIO Initialization Function
* @param None
* @retval None
*/
static void MX_GPIO_Init(void)
{
GPIO_InitTypeDef GPIO_InitStruct = {0};
/* GPIO Ports Clock Enable */
__HAL_RCC_GPIOE_CLK_ENABLE();
__HAL_RCC_GPIOC_CLK_ENABLE();
__HAL_RCC_GPIOH_CLK_ENABLE();
__HAL_RCC_GPIOA_CLK_ENABLE();
__HAL_RCC_GPIOB_CLK_ENABLE();
__HAL_RCC_GPIOD_CLK_ENABLE();
/*Configure GPIO pin Output Level */
HAL_GPIO_WritePin(CS_I2C_SPI_GPIO_Port, CS_I2C_SPI_Pin, GPIO_PIN_RESET);
/*Configure GPIO pin Output Level */
HAL_GPIO_WritePin(OTG_FS_PowerSwitchOn_GPIO_Port, OTG_FS_PowerSwitchOn_Pin, GPIO_PIN_SET);
/*Configure GPIO pin Output Level */
HAL_GPIO_WritePin(GPIOD, LD3_Pin|LD5_Pin|LD6_Pin|Audio_RST_Pin, GPIO_PIN_RESET);
/*Configure GPIO pin : CS_I2C_SPI_Pin */
GPIO_InitStruct.Pin = CS_I2C_SPI_Pin;
GPIO_InitStruct.Mode = GPIO_MODE_OUTPUT_PP;
GPIO_InitStruct.Pull = GPIO_NOPULL;
GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_LOW;
HAL_GPIO_Init(CS_I2C_SPI_GPIO_Port, &GPIO_InitStruct);
/*Configure GPIO pin : OTG_FS_PowerSwitchOn_Pin */
GPIO_InitStruct.Pin = OTG_FS_PowerSwitchOn_Pin;
GPIO_InitStruct.Mode = GPIO_MODE_OUTPUT_PP;
GPIO_InitStruct.Pull = GPIO_NOPULL;
GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_LOW;
HAL_GPIO_Init(OTG_FS_PowerSwitchOn_GPIO_Port, &GPIO_InitStruct);
/*Configure GPIO pin : PDM_OUT_Pin */
GPIO_InitStruct.Pin = PDM_OUT_Pin;
GPIO_InitStruct.Mode = GPIO_MODE_AF_PP;
GPIO_InitStruct.Pull = GPIO_NOPULL;
GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_LOW;
GPIO_InitStruct.Alternate = GPIO_AF5_SPI2;
HAL_GPIO_Init(PDM_OUT_GPIO_Port, &GPIO_InitStruct);
/*Configure GPIO pin : B1_Pin */
GPIO_InitStruct.Pin = B1_Pin;
GPIO_InitStruct.Mode = GPIO_MODE_IT_RISING;
GPIO_InitStruct.Pull = GPIO_NOPULL;
HAL_GPIO_Init(B1_GPIO_Port, &GPIO_InitStruct);
/*Configure GPIO pin : I2S3_WS_Pin */
GPIO_InitStruct.Pin = I2S3_WS_Pin;
GPIO_InitStruct.Mode = GPIO_MODE_AF_PP;
GPIO_InitStruct.Pull = GPIO_NOPULL;
GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_LOW;
GPIO_InitStruct.Alternate = GPIO_AF6_SPI3;
HAL_GPIO_Init(I2S3_WS_GPIO_Port, &GPIO_InitStruct);
/*Configure GPIO pins : SPI1_SCK_Pin SPI1_MISO_Pin SPI1_MOSI_Pin */
GPIO_InitStruct.Pin = SPI1_SCK_Pin|SPI1_MISO_Pin|SPI1_MOSI_Pin;
GPIO_InitStruct.Mode = GPIO_MODE_AF_PP;
GPIO_InitStruct.Pull = GPIO_NOPULL;
GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_LOW;
GPIO_InitStruct.Alternate = GPIO_AF5_SPI1;
HAL_GPIO_Init(GPIOA, &GPIO_InitStruct);
/*Configure GPIO pin : BOOT1_Pin */
GPIO_InitStruct.Pin = BOOT1_Pin;
GPIO_InitStruct.Mode = GPIO_MODE_INPUT;
GPIO_InitStruct.Pull = GPIO_NOPULL;
HAL_GPIO_Init(BOOT1_GPIO_Port, &GPIO_InitStruct);
/*Configure GPIO pin : CLK_IN_Pin */
GPIO_InitStruct.Pin = CLK_IN_Pin;
GPIO_InitStruct.Mode = GPIO_MODE_AF_PP;
GPIO_InitStruct.Pull = GPIO_NOPULL;
GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_LOW;
GPIO_InitStruct.Alternate = GPIO_AF5_SPI2;
HAL_GPIO_Init(CLK_IN_GPIO_Port, &GPIO_InitStruct);
/*Configure GPIO pins : LD3_Pin LD5_Pin LD6_Pin Audio_RST_Pin */
GPIO_InitStruct.Pin = LD3_Pin|LD5_Pin|LD6_Pin|Audio_RST_Pin;
GPIO_InitStruct.Mode = GPIO_MODE_OUTPUT_PP;
GPIO_InitStruct.Pull = GPIO_NOPULL;
GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_LOW;
HAL_GPIO_Init(GPIOD, &GPIO_InitStruct);
/*Configure GPIO pins : I2S3_MCK_Pin I2S3_SCK_Pin I2S3_SD_Pin */
GPIO_InitStruct.Pin = I2S3_MCK_Pin|I2S3_SCK_Pin|I2S3_SD_Pin;
GPIO_InitStruct.Mode = GPIO_MODE_AF_PP;
GPIO_InitStruct.Pull = GPIO_NOPULL;
GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_LOW;
GPIO_InitStruct.Alternate = GPIO_AF6_SPI3;
HAL_GPIO_Init(GPIOC, &GPIO_InitStruct);
/*Configure GPIO pin : VBUS_FS_Pin */
GPIO_InitStruct.Pin = VBUS_FS_Pin;
GPIO_InitStruct.Mode = GPIO_MODE_INPUT;
GPIO_InitStruct.Pull = GPIO_NOPULL;
HAL_GPIO_Init(VBUS_FS_GPIO_Port, &GPIO_InitStruct);
/*Configure GPIO pins : OTG_FS_ID_Pin OTG_FS_DM_Pin OTG_FS_DP_Pin */
GPIO_InitStruct.Pin = OTG_FS_ID_Pin|OTG_FS_DM_Pin|OTG_FS_DP_Pin;
GPIO_InitStruct.Mode = GPIO_MODE_AF_PP;
GPIO_InitStruct.Pull = GPIO_NOPULL;
GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_LOW;
GPIO_InitStruct.Alternate = GPIO_AF10_OTG_FS;
HAL_GPIO_Init(GPIOA, &GPIO_InitStruct);
/*Configure GPIO pin : OTG_FS_OverCurrent_Pin */
GPIO_InitStruct.Pin = OTG_FS_OverCurrent_Pin;
GPIO_InitStruct.Mode = GPIO_MODE_INPUT;
GPIO_InitStruct.Pull = GPIO_NOPULL;
HAL_GPIO_Init(OTG_FS_OverCurrent_GPIO_Port, &GPIO_InitStruct);
/*Configure GPIO pins : Audio_SCL_Pin Audio_SDA_Pin */
GPIO_InitStruct.Pin = Audio_SCL_Pin|Audio_SDA_Pin;
GPIO_InitStruct.Mode = GPIO_MODE_AF_OD;
GPIO_InitStruct.Pull = GPIO_PULLUP;
GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_LOW;
GPIO_InitStruct.Alternate = GPIO_AF4_I2C1;
HAL_GPIO_Init(GPIOB, &GPIO_InitStruct);
/*Configure GPIO pin : MEMS_INT2_Pin */
GPIO_InitStruct.Pin = MEMS_INT2_Pin;
GPIO_InitStruct.Mode = GPIO_MODE_EVT_RISING;
GPIO_InitStruct.Pull = GPIO_NOPULL;
HAL_GPIO_Init(MEMS_INT2_GPIO_Port, &GPIO_InitStruct);
}
/* USER CODE BEGIN 4 */
/* USER CODE END 4 */
/**
* @brief This function is executed in case of error occurrence.
* @retval None
*/
void Error_Handler(void)
{
/* USER CODE BEGIN Error_Handler_Debug */
/* User can add his own implementation to report the HAL error return state */
/* USER CODE END Error_Handler_Debug */
}
#ifdef USE_FULL_ASSERT
/**
* @brief Reports the name of the source file and the source line number
* where the assert_param error has occurred.
* @param file: pointer to the source file name
* @param line: assert_param error line source number
* @retval None
*/
void assert_failed(uint8_t *file, uint32_t line)
{
/* USER CODE BEGIN 6 */
/* User can add his own implementation to report the file name and line number,
tex: printf("Wrong parameters value: file %s on line %d\r\n", file, line) */
/* USER CODE END 6 */
}
#endif /* USE_FULL_ASSERT */
/************************ (C) COPYRIGHT STMicroelectronics *****END OF FILE****/
Last edited:
Now we are ready to roll!
Click on the Debug icon.
With the oscilloscope probe connected to PD12 I measure a toggle interval of 160ns. This is with the PSC and ARR parameters set as follows:
PSC = 0
ARR = 1
Tip: For debugging purposes, you do not have to go back to the MX screen to set these parameters. You can change these directly from the Debug screen. Remember, the timer module is running entirely from hardware. You can suspend code execution and the timer will still continue to run and toggle PD12.
How to use Debug
While in Debug mode, click on SFRs button icon.
Scroll through the list of Registers and expand TIM4 tree.
Click on PSC register and set the desired prescale value. Enter the value in hexadecimal format.
Similarly, set the ARR value.
I can see immediately on the oscilloscope the effect of changing PSC and ARR.
For example, with
PSC = 0
ARR = 1
Toggle Period = 160ns
Toggle Frequency = 6.250MHz
I want to divide the frequency by 6250. Hence I set PSC to 6250-1 = 6249
PSC = 6249 = 0x1869
ARR = 1
Toggle Period = 1ms
Toggle Frequency = 1kHz
Period = 2ms
Frequency = 500Hz
Now that I have a 1kHz time base, I can set ARR to 1000 for 1-second pulses on PD12.
PSC = 0x1869
ARR = 0x3E8
Toggle Period = 0.5 s
Period = 1 s
Frequency = 1Hz
With these numbers, now I can go back to the MX screen and permanently set the PSC and ARR parameters.
Mission accomplished!
Thanks for watching.
Click on the Debug icon.
With the oscilloscope probe connected to PD12 I measure a toggle interval of 160ns. This is with the PSC and ARR parameters set as follows:
PSC = 0
ARR = 1
Tip: For debugging purposes, you do not have to go back to the MX screen to set these parameters. You can change these directly from the Debug screen. Remember, the timer module is running entirely from hardware. You can suspend code execution and the timer will still continue to run and toggle PD12.
How to use Debug
While in Debug mode, click on SFRs button icon.
Scroll through the list of Registers and expand TIM4 tree.
Click on PSC register and set the desired prescale value. Enter the value in hexadecimal format.
Similarly, set the ARR value.
I can see immediately on the oscilloscope the effect of changing PSC and ARR.
For example, with
PSC = 0
ARR = 1
Toggle Period = 160ns
Toggle Frequency = 6.250MHz
I want to divide the frequency by 6250. Hence I set PSC to 6250-1 = 6249
PSC = 6249 = 0x1869
ARR = 1
Toggle Period = 1ms
Toggle Frequency = 1kHz
Period = 2ms
Frequency = 500Hz
Now that I have a 1kHz time base, I can set ARR to 1000 for 1-second pulses on PD12.
PSC = 0x1869
ARR = 0x3E8
Toggle Period = 0.5 s
Period = 1 s
Frequency = 1Hz
With these numbers, now I can go back to the MX screen and permanently set the PSC and ARR parameters.
Mission accomplished!
Thanks for watching.
- Status
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