Hello,
I’m using the IOIO firmware to program a PIC connected to DSPs. I want to
receive digital data from these DSPs via I2C communication, and write this
data to a SD card. My problem is that the data transfer is too slow: by
calling repeatedly the I2CWriteRead function in i2c.c, I can read a 4 byte
register at barely 60Hz. As I wish to receive audio data through I2C, this
frequency should reach at least several kHz. I was wondering if it could be
possible to modify the code to make a burst read on a single register
address input in order to increase the reading speed?
What I already tried:
-Modify the state machine in the MI2CInterrupt function (i2c.c): go back to
“STATE_WRITE_DATA” after “STATE_ACK_READ_DATA” when there are no "bytes
remaining", and rewrite the same address. It leads to error (line 313 in
the original file) and I don’t really know why. (The code to write the
received data to the SD card is in the “STATE_ACK_READ_DATA” state, data is
written to the SD when there are no bytes remaining).
-Call repeatedly the I2CWriteRead function. In order to prevent buffer
overflow, I needed to add a 10 ms delay after each call. It works but it
makes the process very slow. Here is my code:
void SIGMA_READ_REGISTER( int devAddress, int address, int nbRead ){
unsigned char dataAddr[2] = {0x00,0x00};
dataAddr[0] = ((address>>8) & 0xFF); //grab the top 8 bits of the
address
dataAddr[1] = (address & 0xFF); //grab the bottom 8 bits of the address
int i;
for (i=0;i<nbRead;i++){
I2CWriteRead(0, devAddress, &dataAddr[0], 2, 4 );
Delayms(10);
}
}
-Increase the Tx buffer size. It can't be more than 512 (otherwise it leads
to linking memory errors).
Is there a way to read continuously without calling the I2CWriteRead
function each time? Or is it possible to accelerate the reading process?
Thanks for your time and consideration.
Léopold
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