iforce2d:
With the 3.3v arduino the success rate of the i2cRead() call is about 70% versus 50% or so with the 5v arduino. Setting the clock speed of both devices to 100kHz gives markedly better results than 400kHz.By the way, if there are already 1K pullups built into the Flip32+, there is no way I can increase the pullup resistance right? I mean, I can only add resistance in parallel which would decrease the pullup value....
Which device is the master for these traces? The master device controls the clock high. A slave may extend a low (clock stretching) to allow for extra processing time. Basically on a Slave Transmit (onRequestEvent()) after the slave (arduino) has accepted the I2C address the slave holds the clock low, pausing the master (flipp32+) until the onRequestEvent() returns, and the arduino starts sending the data out.
The resistor 1k pulls the clock high after both the slave, and the master have to stop pulling the clock low. So for a 'High' glitch the 'Master' is usually responsible. Is the I2C interface on the flip+ hardware, or is it a bit banger?
Chuck