Hello everyone,
I have started developing software for ABS diagnostic tester.
I am going to use STM32F4 Discovery kit which has 32 bits ARM microcontroller on it.
As a first part of flow char, we should initialize PWM, interrupts, encoder counter with timer unit, and USART to send data back and forth to host device.
Below function initializes TIM5 as an PWM generator by using GPIOA 1. pin as an PWM output.
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| /* | |
| =============================================================== | |
| ### How to use this function ### | |
| =============================================================== | |
| This function can be used to generate PWM signal by using GPIOA's 1. pin. | |
| Function is using TIM5. | |
| PWM hardware configurations | |
| GPIOA's 1.pin is being used for PWM output. | |
| TIM5 was used to generate PWM. | |
| To adjust PWM frequency define variable has been used in RHBE.h | |
| #define RHBE_PERIOD 399 | |
| #define RHBE_PRESCALER 20 | |
| #define RHBE_PWM_CHANNEL CCR2 | |
| #define RHBE_PWM_TIM TIM5 | |
| *** if you want to change frequency of PWM you can play above definations. | |
| */ | |
| void RHBE_InitPWM(void) | |
| { | |
| //definations | |
| GPIO_InitTypeDef GPIO_Config; | |
| TIM_TimeBaseInitTypeDef TIM_Config; | |
| TIM_OCInitTypeDef TIM_OC_Config; | |
| //Clock has been enabled for GPIOA and TIM5. | |
| RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOA, ENABLE); | |
| RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM5, ENABLE); | |
| //AF configurations for PWM output. | |
| GPIO_Config.GPIO_Mode = GPIO_Mode_AF; | |
| GPIO_Config.GPIO_Pin = GPIO_Pin_1; | |
| GPIO_Config.GPIO_OType = GPIO_OType_PP; | |
| GPIO_Config.GPIO_PuPd = GPIO_PuPd_UP; | |
| GPIO_Config.GPIO_Speed = GPIO_Speed_100MHz; | |
| GPIO_Init(GPIOA, &GPIO_Config); | |
| GPIO_PinAFConfig(GPIOA,GPIO_PinSource1,GPIO_AF_TIM5); | |
| //Timer configuration has been done. | |
| TIM_DeInit(RHBE_PWM_TIM); | |
| TIM_Config.TIM_ClockDivision = 0; | |
| TIM_Config.TIM_CounterMode = TIM_CounterMode_Up; | |
| TIM_Config.TIM_Period = RHBE_PERIOD; | |
| TIM_Config.TIM_Prescaler = RHBE_PRESCALER; | |
| TIM_TimeBaseInit(RHBE_PWM_TIM, &TIM_Config); | |
| //Timer was used to generate PWM signal. | |
| TIM_OC_Config.TIM_OCMode = TIM_OCMode_PWM1; | |
| TIM_OC_Config.TIM_OCPolarity = TIM_OCPolarity_High; | |
| TIM_OC_Config.TIM_OutputState = TIM_OutputState_Enable; | |
| TIM_OC_Config.TIM_Pulse = 0; | |
| TIM_OC2Init(RHBE_PWM_TIM, &TIM_OC_Config); | |
| TIM_OC2PreloadConfig(RHBE_PWM_TIM,TIM_OCPreload_Enable); | |
| TIM_ARRPreloadConfig(RHBE_PWM_TIM,ENABLE); | |
| TIM_Cmd(RHBE_PWM_TIM,ENABLE); | |
| } |
Since it is hard to remember CCR2 value, I'll create function to be able to set PWM output with percentage.
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| /* | |
| =============================================================== | |
| ### How to use this function ### | |
| =============================================================== | |
| This function can be used to set PWM duty cycle denominated %percent. | |
| Function can get value from 0 to 100 percent. | |
| */ | |
| void RHBE_SetPWMDutyCycle(uint8_t cycle) | |
| { | |
| uint16_t pulse; | |
| pulse = (((RHBE_PERIOD +1) * cycle) / 100) - 1; //calculation from percentage to pulse. | |
| RHBE_PWM_TIM -> RHBE_PWM_CHANNEL = pulse; //value has been assigned to directly to register. | |
| } |
We need to set interrupt for button to start program. It might be handled with a simple loop that always looks button input. However, this loop spends sources unnecessarily. Here is the initialization code to set up button intterrupt.
ABS signal output will generate either 5V or GND based on tone wheel position. This signal will trigger interrupt. This interrupts will be used to count encoder input. If there is correct match we can assume that tone wheel has perfect inner shape. Here is the interrupt that will trigger interrupt function where we will count encoder output to see if there is match.
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| /* | |
| =============================================================== | |
| ### How to use this function ### | |
| =============================================================== | |
| This function is to set external interrupt for RR Hub bearing signal. | |
| RR hub bearing will produce signal which is 5V or GND. | |
| In every changing system will go into to this function to understan DC motor rotation value. | |
| Interrupt hardware configurations | |
| GPIOB is being used. | |
| Pin is 1. | |
| ***Trigger edge is rising-falling for default. | |
| */ | |
| void RHBE_InitABSSignalInterrupt(void) | |
| { | |
| //Definations | |
| GPIO_InitTypeDef GPIO_Config; | |
| EXTI_InitTypeDef EXTI_Config; | |
| NVIC_InitTypeDef NVIC_Config; | |
| //Enabled clock signal for GPIOB and SYSCFG | |
| RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOB, ENABLE); | |
| RCC_APB2PeriphClockCmd(RCC_APB2Periph_SYSCFG, ENABLE); | |
| //External interrupt pin configuation has been done. | |
| GPIO_Config.GPIO_Mode = GPIO_Mode_IN; | |
| GPIO_Config.GPIO_Pin = GPIO_Pin_1; | |
| GPIO_Config.GPIO_PuPd = GPIO_PuPd_DOWN; | |
| GPIO_Config.GPIO_Speed = GPIO_Speed_100MHz; | |
| GPIO_Init(GPIOB,&GPIO_Config); | |
| //GPIOB's 1. pin has been assigned for external interrupt. | |
| SYSCFG_EXTILineConfig(EXTI_PortSourceGPIOB,EXTI_PinSource1); | |
| //Configuration of external interrupt. | |
| EXTI_Config.EXTI_Line = EXTI_Line1; | |
| EXTI_Config.EXTI_LineCmd = ENABLE; | |
| EXTI_Config.EXTI_Mode = EXTI_Mode_Interrupt; | |
| EXTI_Config.EXTI_Trigger = EXTI_Trigger_Rising_Falling; | |
| EXTI_Init(&EXTI_Config); | |
| //requested interrupt. | |
| NVIC_Config.NVIC_IRQChannel = EXTI1_IRQn; | |
| NVIC_Config.NVIC_IRQChannelCmd = ENABLE; | |
| NVIC_Init(&NVIC_Config); | |
| } |
We are almost done with with all initialization. Now we need to setup timer unit as counter to count encoder output. Since I used quadrature encoder, it has two channel outputs that create +-90 degree phase difference between channels. If motor turns clockwise, phase difference is 90 degree, on contrary it is -90 degree for counter clockwise. Here is the timer setting to be able to use it as a counter.
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| /* | |
| =============================================================== | |
| ### How to use this function ### | |
| =============================================================== | |
| This function enables TIM4 for encoder counter. | |
| Function will set Timer channels as encoder counter. | |
| Encoder A will be connected to GPIOB's 6th pin. | |
| Encoder B will be connected to GPIOB's 7th pin. | |
| TIM4 will count in every edge of signal of A and B. | |
| Interrupt hardware configurations | |
| GPIOB is being used. | |
| Pin is 6 and 7. | |
| */ | |
| void RHBE_InitEncoder(void) | |
| { | |
| //Created GPIO struct. | |
| GPIO_InitTypeDef GPIO_Config; | |
| //enabled clock source for GPIOB, TIM4 | |
| RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOB, ENABLE); | |
| RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM4, ENABLE); | |
| //GPIO settings to for Timer Channels | |
| GPIO_Config.GPIO_Mode = GPIO_Mode_AF; | |
| GPIO_Config.GPIO_PuPd = GPIO_PuPd_UP; | |
| GPIO_Config.GPIO_Pin = GPIO_Pin_6 | GPIO_Pin_7; | |
| GPIO_Init(GPIOB, &GPIO_Config); | |
| //Pins are connected to AF. | |
| GPIO_PinAFConfig(GPIOB,GPIO_PinSource6, GPIO_AF_TIM4); | |
| GPIO_PinAFConfig(GPIOB,GPIO_PinSource7, GPIO_AF_TIM4); | |
| //Timer was set as an two channel counter. | |
| TIM_EncoderInterfaceConfig (TIM4, TIM_EncoderMode_TI12, | |
| TIM_ICPolarity_Rising, | |
| TIM_ICPolarity_Rising); | |
| TIM_SetAutoreload (TIM4, 0xffff); | |
| //Timer is being ran with above settings. | |
| TIM_Cmd(TIM4,ENABLE); | |
| } |
We need to initialize USART lastly to communicate host device to show messages, result and other human interfaces.
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| /* | |
| =============================================================== | |
| ### How to use this function ### | |
| =============================================================== | |
| This function is to initilaze USART 2 for serial communication. | |
| GPIO A has been used. | |
| Pin 2 and pin 3 has been used for communication. | |
| */ | |
| void RHBE_InitUSART(void) | |
| { | |
| //Declared Init structs. | |
| USART_InitTypeDef USART_InitStruct; | |
| GPIO_InitTypeDef GPIO_InitStruct; | |
| //Enabled clock sources for USART2 and GPIOA. | |
| RCC_APB1PeriphClockCmd(RCC_APB1Periph_USART2, ENABLE); | |
| RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOA, ENABLE); | |
| //USART will be initialized based on below settings. | |
| USART_InitStruct.USART_BaudRate = 115200; | |
| USART_InitStruct.USART_WordLength = USART_WordLength_8b; | |
| USART_InitStruct.USART_StopBits = USART_StopBits_1; | |
| USART_InitStruct.USART_Parity = USART_Parity_No; | |
| USART_InitStruct.USART_Mode = USART_Mode_Tx; | |
| USART_InitStruct.USART_HardwareFlowControl = USART_HardwareFlowControl_None; | |
| //Usart is being ran with above settings. | |
| USART_Init(USART2,&USART_InitStruct); | |
| USART_Cmd(USART2, ENABLE); | |
| //USART pin has been arranged as AF. | |
| GPIO_InitStruct.GPIO_Mode = GPIO_Mode_AF; | |
| GPIO_InitStruct.GPIO_Pin = GPIO_Pin_2 | GPIO_Pin_3; | |
| GPIO_InitStruct.GPIO_Speed = GPIO_Speed_100MHz; | |
| GPIO_Init(GPIOA,&GPIO_InitStruct); | |
| GPIO_PinAFConfig(GPIOA,GPIO_PinSource2,GPIO_AF_USART2); | |
| GPIO_PinAFConfig(GPIOA,GPIO_PinSource3,GPIO_AF_USART2); | |
| } |
We completed initialization and definations. Here are codes are scatter since aim of this note is to explain details. If you want to see neat codes please visit my GitHub.
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