Posted on April 29, 2007 at 14:17Hi,
We are trying to write an I2C driver for the ST10F276 (ST10F276Z5T3 - working at 40Mhz) and we encounterd the following problem:
we use the function below to send the start bit, but it doesn't work ( I2CSR1 bit 0 does not rise )without the delay of about 100uSec between the the assignment of I2C_START value to the I2CCR register and querying of the I2CSR1 register.
Is there a reason for this delay?
we copied this driver from a prior product which used ST10F276 also but worked at 64Mhz and no delay was needed there.
thanks in advance,
Dvir
//------------------------------------------------------------------------
#define I2C_START ((unsigned char)0x08)
#define I2C_SB 0x0001
byte I2C_TransmitStartBit(void)
{
word wSavedTime;
word wIndex;
I2CCR |= I2C_START;
wSavedTime = INT_dwGetTime(); // 1mSec resolution
//************************************************************************
// ~100uSec delay
for (wIndex = 0; wIndex < 150 ; wIndex++ )
{
_nop();
}
//************************************************************************
if ((I2CSR1 & I2C_SB) == 0)
{
if (( INT_dwGetTime() - wSavedTime ) > 3)
{
return(FALSE);
}
}
return(TRUE);
}
//------------------------------------------------------------------------
