Posted on May 13, 2015 at 01:17Hi,
I have an application where I configure a OV7670 camera by SCCB bus (Omnivision thing) emulated by I2C...
I used this sucessfully for couple of months but yesterday I disassembled the PCB that I have made for that application and made some changes that arent related to the SCCB. After I put the PCB back with the kit the configuration that I have used for a few months stopped working...
The function that I use is listed below...It gets stuck at while(!I2C_CheckEvent(I2C1, I2C_EVENT_MASTER_TRANSMITTER_MODE_SELECTED))...
But the strangest thing that if I unplug the camera and connect all the pins through 20cm cable then the configuration works again. I found that out by testing if the module works at all. Simply if I add 20cm of cable (no pins were swapped) then it works again...
I think it has something to do with the interference comming from DCMI but shouldnt the cables make it even worse?
I have no rational explanation...Thanks very much for help...
uint8_t SCCB_write_reg(uint8_t reg_addr, uint8_t* data){
uint32_t timeout = SCCB_TIMEOUT;
// Send start bit
I2C_GenerateSTART(I2C1, ENABLE);
// Wait until I2C is busy
while(!I2C_GetFlagStatus(I2C1, I2C_FLAG_SB)){
if ((timeout--) == 0)
return 1;
}
while( !I2C_CheckEvent(I2C1,I2C_EVENT_MASTER_MODE_SELECT)){
if ((timeout--) == 0)
return 1;
}
// Send slave address (OV7670_WRITE_ADDR)
I2C_Send7bitAddress(I2C1, OV7670_WRITE_ADDR, I2C_Direction_Transmitter);
while(!I2C_CheckEvent(I2C1, I2C_EVENT_MASTER_TRANSMITTER_MODE_SELECTED)){
if ((timeout--) == 0)
return 1;
}
// Send register address
I2C_SendData(I2C1, reg_addr);
while(!I2C_CheckEvent(I2C1,I2C_EVENT_MASTER_BYTE_TRANSMITTED)){
if ((timeout--) == 0)
return 1;
}
// Send new register value
I2C_SendData(I2C1, *data);
while(!I2C_CheckEvent(I2C1,I2C_EVENT_MASTER_BYTE_TRANSMITTED)){
if ((timeout--) == 0)
return 1;
}
// Send stop bit
I2C_GenerateSTOP(I2C1, ENABLE);
// Write done
return 0;
}
#stm32 #i2c #dcmi #sccb
