Hi,
I am trying to communicate with a bq34z100 with a mikrocontroller via i2c.
Everything is working ok so far, there is however one strange behaviour.
After I activate the board (set power supply to on) and try to start communicating with the bq34z100 before ~2s have passed (>350ms for startup delay) then the communication will only work for a short time (<1s) and then the clock line will be pulled low for 2s.
If I start the communication with a delay >2s then this behaviour cannot be seen and the communication stays normal. It does not matter if I put the delay in front of the program or just wait for starting the communication with the bq34z100 later in my program.
The setup: LM4F µC connected to bq77pl900 and bq34z100. Internal pullups of bq77pl900. (bq77pl900 communications start after 8ms of powerup and is ok).
The communication consists of the readout of the devicename (-> AA 63 ...). This also returns the correct value (bq34z100) except for that time described above. Then the clock and data line stay low after AA 63, after a while (5ms) the microcontroller detects the hang and let's go of the data line so it is pulled up, however the clock line is still pulled low (clockstretching?) for 2s. Then the clock line is released the communication restarts and everything works fine from there on.
I checked the CE and REGIN, they are at stable 3,3V, also the REG25 is stable at 2,5V after startup.
Has anyone observed anything like that before? Or is there a startup delay in the datasheet I have missed?
Greetings!
Jan