Dear Sir,
I add a I2C mux to extend CX3 I2C bus , but it doesn't work, I cannot see any I2C wave from the output of PCA9540B, I also call read channel status, it seems no any change. status return from write and raed API seem ok !
only two commands are supported, one is write channel (xxxxxB2B1B0), the other is read channel status(xxxxxB2B1B0).
The following is my code, are preamble filled correctly? any comments will be appreciated!
/*
* pca9540b.c
*
* Created on: 2017年9月19日
* Author: lenovo
*/
#include <cyu3error.h>
#include <cyu3i2c.h>
#include <cyu3os.h>
//#include <cyu3types.h>
//#include "pca9540b.h"
#define PCA9540B_IIC_ADDR 0x70
const uint8_t PCA9540B_IIC_WRITEADDR = 0xe0;//PCA9540B_IIC_ADDR << 1;
const uint8_t PCA9540B_IIC_READADDR = 0xe1;//(PCA9540B_IIC_ADDR << 1)|1;
// control byte true table
// D7 D6 D5 D4 D3 D2 D1 D0 channel
// x x x x x 0 x x no channel selected
// x x x x x 1 0 0 CH0 enable
// x x x x x 1 0 1 CH1 enable
// x x x x x 1 1 x no channel selected
// 0 0 0 0 0 0 0 0 no channel selected;power-up default state
const uint8_t PCA9540B_CH[3] =
{
0x04, // channel 0
0x05, // channel 1
0x00 // both of channels 0,1 are disable
};
uint32_t pca9540b_SetCh(uint32_t ch)
{
CyU3PReturnStatus_t status = CY_U3P_SUCCESS;
CyU3PI2cPreamble_t preamble;
uint8_t data[32] ={0}; //just for api calling,if NULL is called,0x41 will be return by CyU3PI2cTransmitBytes()
static uint32_t ch_1 = 2; // PCA9540B_CH[2] = 0x00, all are disable
if(ch > 2) return CY_U3P_ERROR_BAD_ARGUMENT; // only 0,1 channel is permitted
if ( ch == ch_1) return CY_U3P_SUCCESS; // no real switch action
preamble.buffer[0] = PCA9540B_IIC_WRITEADDR;
preamble.buffer[1] = PCA9540B_CH[ch];
preamble.length = 2;
preamble.ctrlMask = 0x0000;
status = CyU3PI2cTransmitBytes(&preamble,data,0,0);
if(status != CY_U3P_SUCCESS)
CyU3PDebugPrint(4,"\n\rErr: pca9540b_SetCh failed! status = %x\n\r",status);
else
ch_1 = ch;
return status;
}
// read channel configuration
uint32_t pca9540b_GetCh(uint8_t *ch_status)
{
CyU3PReturnStatus_t status = CY_U3P_SUCCESS;
CyU3PI2cPreamble_t preamble;
preamble.buffer[0] = PCA9540B_IIC_READADDR;
preamble.length = 1;
preamble.ctrlMask = 0x0000;
status = CyU3PI2cReceiveBytes(&preamble,ch_status,1,0); // only one byte read
CyU3PThreadSleep(1);
if (status != CY_U3P_SUCCESS)
CyU3PDebugPrint(4,"\n\rErr: pca9540b_GetCh failed! status = %x\n\r",status);
return status;
}
