digital sampling of GPIO

developer2 · ‎2013-05-25

Posted on May 26, 2013 at 00:35

Hi,

is it possible to sample GPIOA Bit7-0 into SRAM as byte and to have kind of ''Clk'' nonPWM output on other GPIO ,

with higher speed than 20MHz on STM32F103 72MHz ?

this gives me 10MHz clk output on PC2:

Buffer_ptr=(uint8_t *)Buffer;

while( 1 )

{

*(Buffer_ptr++)=(uint8_t)GPIOA->IDR;

GPIOC->ODR = GPIO_Pin_2;

if(Buffer_ptr>=(uint8_t *)(Buffer+20000))

break;

GPIOC->ODR = 0;

}

Thank You for all replies

Tesla DeLorean · ‎2013-05-25

Posted on May 26, 2013 at 02:00

DMA transfer of a GPIOx->ODR, triggered by a TIM, output of same trigger pulse. Speed of the APB may be a limiting factor here. Consider a different part from the F2/F4 series.

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developer2 · ‎2013-05-26

Posted on May 26, 2013 at 09:05

i tried this with DMA:

Buff_PC2[0]=0;

Buff_PC2[1]=GPIO_Pin_2;

DMA_InitStructure.DMA_PeripheralBaseAddr = (uint32_t)(&GPIOC->ODR);

DMA_InitStructure.DMA_MemoryBaseAddr = (uint32_t)Buff_PC2;

DMA_InitStructure.DMA_DIR = DMA_DIR_PeripheralDST;

DMA_InitStructure.DMA_BufferSize = 2;

DMA_InitStructure.DMA_PeripheralInc = DMA_PeripheralInc_Disable;

DMA_InitStructure.DMA_MemoryInc = DMA_MemoryInc_Enable;

DMA_InitStructure.DMA_PeripheralDataSize = DMA_PeripheralDataSize_Byte;

DMA_InitStructure.DMA_MemoryDataSize = DMA_MemoryDataSize_Byte;

DMA_InitStructure.DMA_Mode = DMA_Mode_Circular;

DMA_InitStructure.DMA_Priority = DMA_Priority_VeryHigh;

DMA_InitStructure.DMA_M2M = DMA_M2M_Disable;

DMA_Init(DMA2_Channel1 , &DMA_InitStructure);

TIM_TimeBaseStructure.TIM_Period = 1;

TIM_TimeBaseStructure.TIM_Prescaler = 0x00;

TIM_TimeBaseStructure.TIM_ClockDivision = 0;

TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;

TIM_TimeBaseInit( TIM8, &TIM_TimeBaseStructure);

TIM_UpdateRequestConfig( TIM8, TIM_UpdateSource_Regular );

DMA_Cmd( DMA2_Channel1, ENABLE);

TIM_Cmd( TIM8, ENABLE);

this generates 600kHz,

did i make mistake somewhere in initialization ?