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STM32f0308-DISCO read from RTC PCF8583

prashanth
Associate II
Posted on July 31, 2014 at 16:30

Hello Everyone,

I have started to work on the STM32F0308 discovery board. Now I am trying to read data from the RTC PCF8583 using I2C. I do not have prior experience with I2C. 

My problem is that I am not able to read data from the RTC (Output on terminal in Run mode:  <0><0><0>) . 

Please check my code and let me know what I have done is correct ... Please educate me on this.

CODE:

void usartInit()

{

RCC_AHBPeriphClockCmd(RCC_AHBPeriph_GPIOA, ENABLE);

RCC_APB2PeriphClockCmd(RCC_APB2Periph_USART1, ENABLE);

GPIO_InitTypeDef GPIO_InitStructure;

GPIO_StructInit(&GPIO_InitStructure);

GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF;

GPIO_InitStructure.GPIO_Pin = GPIO_Pin_10 | GPIO_Pin_9;

GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;

GPIO_InitStructure.GPIO_OType = GPIO_OType_PP;

GPIO_Init(GPIOA, &GPIO_InitStructure);

GPIO_PinAFConfig(GPIOA, GPIO_PinSource10, GPIO_AF_1);

GPIO_PinAFConfig(GPIOA, GPIO_PinSource9, GPIO_AF_1);

USART_InitTypeDef USART_InitStructure ;

USART_StructInit(&USART_InitStructure);

USART_InitStructure.USART_BaudRate = 9600;

USART_InitStructure.USART_Mode = USART_Mode_Tx | USART_Mode_Rx;

USART_InitStructure.USART_Parity = USART_Parity_No;

USART_InitStructure.USART_StopBits = USART_StopBits_1;

USART_InitStructure.USART_WordLength = USART_WordLength_8b;

USART_InitStructure.USART_HardwareFlowControl = USART_HardwareFlowControl_None;

USART_Init(USART1, &USART_InitStructure);

USART_Cmd(USART1, ENABLE);

}

void TIM17_IRQHandler()

{

TIM_ClearITPendingBit(TIM17 ,TIM_IT_Update);

i2c_call();

}

void vTimer17_init()

{

TIM_TimeBaseInitTypeDef TIM_InitStructure;

NVIC_InitTypeDef NVIC_InitStructure;

RCC_APB2PeriphClockCmd(RCC_APB2Periph_TIM17, ENABLE);

TIM_TimeBaseStructInit(&TIM_InitStructure);

TIM_InitStructure.TIM_Prescaler = 4800-1;

TIM_InitStructure.TIM_Period = 100-1;

TIM_InitStructure.TIM_CounterMode = TIM_CounterMode_Up;

TIM_InitStructure.TIM_ClockDivision = 0;

TIM_TimeBaseInit(TIM17,&TIM_InitStructure );

TIM_Cmd(TIM17, ENABLE);

NVIC_InitStructure.NVIC_IRQChannel = TIM17_IRQn;

NVIC_InitStructure.NVIC_IRQChannelPriority = 3;

NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;

NVIC_Init (& NVIC_InitStructure);

NVIC_EnableIRQ(TIM17_IRQn);

TIM_ITConfig(TIM17 , TIM_IT_Update , ENABLE);

}

void i2c_call()

{

uint16_t sec;

I2C_TransferHandling(I2C1, 0xA0,1, I2C_AutoEnd_Mode, I2C_Generate_Start_Write);

I2C_SendData(I2C1, 0x02);

I2C_TransferHandling(I2C1, 0xA1,1, I2C_AutoEnd_Mode, I2C_Generate_Start_Read);

sec = I2C_ReceiveData(I2C1);

I2C_GenerateSTOP(I2C1, ENABLE);

while (USART_GetFlagStatus(USART1, USART_FLAG_TXE) == RESET);

USART_SendData(USART1, sec);

}

void i2c1_init()

{

RCC_AHBPeriphClockCmd(RCC_AHBPeriph_GPIOB, ENABLE);

RCC_AHBPeriphClockCmd(RCC_AHBPeriph_GPIOC, ENABLE);

RCC_APB1PeriphClockCmd(RCC_APB1Periph_I2C1, ENABLE);

GPIO_InitTypeDef GPIO_InitStructure;

GPIO_StructInit(&GPIO_InitStructure);

GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF;

GPIO_InitStructure.GPIO_Pin = GPIO_Pin_8 | GPIO_Pin_9;

GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;

GPIO_Init(GPIOB, &GPIO_InitStructure);

GPIO_PinAFConfig(GPIOB, GPIO_PinSource8, GPIO_AF_1);

GPIO_PinAFConfig(GPIOB, GPIO_PinSource9, GPIO_AF_1);

I2C_InitTypeDef I2C_InitStructure;

I2C_StructInit(&I2C_InitStructure);

I2C_InitStructure.I2C_Mode = I2C_Mode_I2C;

I2C_InitStructure.I2C_Ack = I2C_Ack_Disable;

I2C_InitStructure.I2C_OwnAddress1 = 0x5A;

I2C_InitStructure.I2C_AcknowledgedAddress = I2C_AcknowledgedAddress_7bit;

I2C_InitStructure.I2C_AnalogFilter = I2C_AnalogFilter_Disable;

I2C_InitStructure.I2C_DigitalFilter = 0x00;

I2C_InitStructure.I2C_Timing = 0x00B01A4F;

I2C_Init(I2C1, &I2C_InitStructure);

I2C_Cmd(I2C1, ENABLE);

}

int main(void)

{

i2c1_init();

usartInit();

vTimer17_init();

while(1)

{

}

  return 0;

}

PS : I know there is an inbuilt RTC in the chip which I am using. But I want to try interfacing with an external RTC and to get some familiarity with I2C. 

Thanks in Advance

Prashanth

#discovery #stm32 #i2c #stm32f0
2 REPLIES 2
Posted on July 31, 2014 at 18:31

You must configure the I2C pins in OD (Open Drain) mode, with either an internal or external pull up.

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prashanth
Associate II
Posted on July 31, 2014 at 19:01

I have configured the I2C pin in OD mode and it is externally pulled up. Still it does not work. But when I run in debug mode by stepping in I can see some values. Unfortunately the values does not appear in normal run mode.

Thanks,  

Prashanth