DSP上I2C0与uPP同时工作的问题

补充：如果关掉uPP，则i2c0的通信就很可靠，基本不会出现失败的情况，请指教

请问用的是哪款器件？

I2C是否接了上拉电阻？~5K pull ups on both lines (only one set, or two sets of 10K pull ups) are recommended

你好！用的omap-L138， I2C已经加5.1K的电阻

请检查layout ,看I2C时钟线，信号线周围是不是有大干扰源，比如电源，电感，时钟信号等。特别看一下uPP的clock是否干扰了I2C。

请问，除了layout，是否还有可能是其他原因引起的？因为我关闭uPP只是reset了它，但是时钟和数据线的波形还是会产生的，并不会影响到我的i2c使用，请看我的代码。

#include <stdio.h>
#include "shared/protocol.h"
#include <stdlib.h>
//#include <stdint.h>
#include <uartStdio.h>
#include "evmOMAPL138.h"
#include "uart.h"
#include "soc_OMAPL138.h"
#include "hw_types.h"
#include "hw_syscfg0_OMAPL138.h"
#include <c674x/omapl138/interrupt.h>
#include <hw/soc_C6748.h>
#include <delay.h>
#include "fpga_upp.h"
#include "I2c_fpga.h"
#include "laser.h"
#define random(x) (rand()%x)

extern __SHM_RO data_type_ptr;
#define UPP_RX_LNCNT        1
///   S12443_CCD    2532     东芝的  TCD1254GFG    10128
#define UPP_RX_BCNT	         2532
#define UPP_DMA_BCNT	     UPP_RX_BCNT*2
uint16_t    recv_adc_buffer[UPP_RX_LNCNT*UPP_RX_BCNT];

uint8_t request_raw_data = 0;

//extern inline void dsp_delay(int ccc);

void ISR_ReceivedCMDFromARM(void);


void mydelay(unsigned long long t)
{
	while(t--);
}
int main(void) {

	uint8_t data[2048] = {0};
	uint32_t i=655355;
	uint32_t count = 0;
	double res = 0.0;
	unsigned int j = 3000;
	U8 ret = 0;
    // 全局中断初始化
	IntDSPINTCInit();
	IntGlobalEnable();
	//初始化核间通信中断机制
	DSP_CHIPSIG2_Init(ISR_ReceivedCMDFromARM);
	SHM_DSP_Init();
	UARTprintf("-------DSP has startup.------------\n");

	//配置杂七杂八
	FPGA_init_i2c();
	fpga_writeRegister(1,0);
	dsp_delay(1000);
	fpga_writeRegister(1,7);
	dsp_delay(1000);
	fpga_writeRegister(2,50);
	dsp_delay(1000);
	UPP_PINMUX();
	config_upp();

	//laser_on(1);
	//laser_on(0);


	int frcnt;
	frcnt=0;
	int cc = 0;
	int done = 0;
	UARTprintf("--------write start------------\n");
	while(1/*frcnt < 100000*/)
	{
		config_upp();//只要有调用了这个函数，i2c就会被影响, 这个函数只调用了void  UPP_init(upp_config_t * config)；
		recv_adc_buffer[2531]=1;
		upp_receive_fifo(recv_adc_buffer,UPP_RX_LNCNT,UPP_DMA_BCNT);
		while(1)
		{
			if(recv_adc_buffer[2531]!=1 )
			{
				frcnt++;
		    	if(*data_type_ptr == 0x01)//写入结果数据
		    	{
		    		res = frcnt;//recv_adc_buffer[10] * recv_adc_buffer[100] / 1000.0f;
		    		ret = SHM_DSP_Write_Res((U8 *)&res, sizeof(double));
		    		if(ret == SHM_SUCCEED)
		    		{
		    			done ++;
		    		}
		    	}
		    	else if(*data_type_ptr == 0x02)//写入原始数据
		    	{
		    		if(request_raw_data == 1)
		    		{
		    			ret = SHM_DSP_Write_Raw((unsigned char *)recv_adc_buffer, RAW_BLOCK_SIZE);
		    			request_raw_data = 0;
		    		}

		    	}
		    	cc++;
				break;
			}
		}
		continue;


	}

	UARTprintf("--------write frame:%d, succeed:%d------------\n", frcnt, done);

}


//
void  UPP_init(upp_config_t * config)
{
	uint32_t i = 0;

	//Provide power to uPP
	//EVMOMAPL138_lpscTransition(PSC1, DOMAIN0, LPSC_RPI, PSC_ENABLE);

	//reset uPP
	SETBIT(UPP->UPPCR, UPP_UPPCR_SWRST);

	for(i = 0; i < 200; i++){};  	//wait 200 clock cycles for reset.
	CLRBIT(UPP->UPPCR, UPP_UPPCR_SWRST);

	//setup control registers
/*	UPP->UPCTL=config->UPCTL.value;
	UPP->UPICR=config->UPICR.value;
	UPP->UPIVR=config->UPIVR.value;
	UPP->UPTCR=config->UPTCR.value;
	UPP->UPDLB=config->UPDLB.value;
	UPP->UPIES=config->UPIES.value;
	UPP->UPPCR=config->UPPCR.value;*/
	//UPP->UPICR |= ((0x3<<19)|(0x3<<3));  //START signal is enabled.
}

我还是比较倾向于硬件上的问题。

请问omap-L138的DSP的I2C是否支持时钟延展（SCL Stretching）？

支持时钟延展。TRM手册中有说明。

As a slave, the I2C peripheral does not generate the clock signal,
but it can hold I2Cx_SCL low while the intervention of the processor is required (RSFULL = 1 in
ICSTR) after data has been received.

Table 23-1. Operating Modes of the I2C Peripheral
http://www.ti.com/lit/ug/spruh77c/spruh77c.pdf

问题解决了，确实是复位uPP会影响到I2C的通信，导致I2C的通信产生很大延迟（约1ms），不重新配置Upp而是重新配置DMA就可以解决，不知道是怎么影响的，影响I2C的语句：

//reset uPP
SETBIT(UPP->UPPCR, UPP_UPPCR_SWRST);

for(i = 0; i < 200; i++){}; //wait 200 clock cycles for reset.
CLRBIT(UPP->UPPCR, UPP_UPPCR_SWRST);