Hi all,
I am trying to communicate to a TMP101 chip (I actually have three on my board, so every address is used 48, 49 and 4A). I am using MCCs iPort USB to communicate on the i2c line. According to the iPort USB users guide, I would enter an address in the form aaaa aaa0 to read (or write to). Therefore I am attempting to read address 90, 92, or 94. Unfortunately I am not getting any acknowledge from the TMP101 chips. I set up an oscilloscope to read the SCL and SDA lines, and I see the correct addresses going out so I dont believe it is an addressing problem. I am operating at VCC = 3.3V, and the high voltage levels for SCL and SDA are 3.26V, the low voltage levels during my attempt to communicate are about 0.3V. The i2c bus clock rate is 400kHz. I checked the power pins on the TMP101 chips and everything seemed to be in order. There is a 900ns time difference between the SDA line going high (increasing past 2.3V) to the SCL clock going high.
Does anybody know what my problem could be? Any help with troubleshooting this would be greatly appreciated :)