Posted on March 24, 2014 at 23:23
Thank you very much for your answer :), I already read that thread and noticed that there are a function (GPIO_PinAFConfig) which is not in my development environment (CooCox IDE 1.7.6), but then I have used GPIO_PinRemapConfig(GPIO_FullRemap_TIM3, ENABLE);
now it seems to work with external clock, however I have now another problem:What exactly I wanto to make is to connect RFID Frond-End chip EM4095 with STM32. I am using two outputs of EM4095, RDY/CLK and DEMOD_OUT. I have a small osciloscope (DSO QUAD) and I upload the scope picture.
EM4095 outputs a square wave on RDY/CLK pin at 125 KHz as expected. If there is no RFID tag in front of the coil, it gives a square wave on DEMOD_OUT pin at ~3.600 KHz. I am using EXTI interrupts for that input and I want to count the RDY/CLK cycles until next rising edge of DEMOD_OUT, therefore I configured the TIM3 so that it will count up on each rising edge of RDY/CLK signal.
As you can see on the picture below, the TIM3 shall give 31 or 32 until next interrupt, but it gives always 0 or 1. Blue line is RDY/CLK, yellow is DEMOD_OUT.
void
EXTI_Exp(
void
)
{
RCC_Configuration();
NVIC_Configuration();
GPIO_Configuration();
Timer_Configuration(); //other configurations like USART and LCDGPIO_EXTILineConfig(GPIO_PortSourceGPIOC, GPIO_PinSource6);
EXTI_InitStructure.
EXTI_Line
= EXTI_Line6;
EXTI_InitStructure.EXTI_Mode
=
EXTI_Mode_Interrupt
;
EXTI_InitStructure.EXTI_Trigger
=
EXTI_Trigger_Rising
;
EXTI_InitStructure.EXTI_LineCmd
=
ENABLE
; EXTI_Init(&EXTI_InitStructure);while
(1)
{ }}
void
GPIO_Configuration(
void
)
{
// Input for DEMOD_OUT and RDY/CLK signal from EM4095
GPIO_InitStructure.
GPIO_Mode
=
GPIO_Mode_IN_FLOATING
;
GPIO_InitStructure.
GPIO_Pin
= GPIO_Pin_6;
GPIO_Init(GPIOC, &GPIO_InitStructure);
GPIO_InitStructure.
GPIO_Mode
=
GPIO_Mode_IN_FLOATING
;
GPIO_InitStructure.
GPIO_Pin
= GPIO_Pin_7;
GPIO_Init(GPIOC, &GPIO_InitStructure);
GPIO_PinRemapConfig(GPIO_FullRemap_TIM3,
ENABLE
);}
void
Timer_Configuration(
void
){
TIM_TimeBase_InitStructure.
TIM_ClockDivision
= TIM_CKD_DIV1;
TIM_TimeBase_InitStructure.
TIM_CounterMode
= TIM_CounterMode_Up;
TIM_TimeBase_InitStructure.
TIM_Period
= 65535;
TIM_TimeBase_InitStructure.
TIM_Prescaler
= 0;
TIM_TimeBaseInit(TIM3, &TIM_TimeBase_InitStructure);
TIM_Cmd(TIM3,
ENABLE
);TIM_TIxExternalClockConfig(TIM3, TIM_TIxExternalCLK1Source_TI2, TIM_ICPolarity_Rising, 0);
}
void
NVIC_Configuration(
void
)
{
// Enable EXTI 9-5 Lines interrupt
NVIC_InitStructure.
NVIC_IRQChannel
= EXTI9_5_IRQn;
NVIC_InitStructure.
NVIC_IRQChannelPreemptionPriority
= 0;
NVIC_InitStructure.
NVIC_IRQChannelSubPriority
= 0;
NVIC_InitStructure.
NVIC_IRQChannelCmd
=
ENABLE
;
NVIC_Init(&NVIC_InitStructure);
}
void
RCC_Configuration(
void
){
RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA | \
RCC_APB2Periph_GPIOC | \
RCC_APB2Periph_GPIOB | \
RCC_APB2Periph_AFIO ,
ENABLE
);
RCC_APB1PeriphClockCmd( RFID_TIM_RCC | \
RCC_APB1Periph_TIM3 | \
RCC_APB1Periph_USART2 | \
RCC_APB1Periph_USART3,
ENABLE
);}
</p>
void
</b>
EXTI9_5_IRQHandler(
void
)
{
uint8_t i;
if
(EXTI_GetFlagStatus(EXTI_Line6) ==
SET
) {
EXTI_ClearITPendingBit(EXTI_Line6);
iCnt = TIM_GetCounter(TIM3);
LCD_SendText(
'':''
);LCD_SendNumber(iCnt);
TIM_SetCounter(TIM3, 0);
}
I am calling EXTI_Exp() function in the main.c
