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Precision Data Converters
Precision Data Converters Forum
ADS1100 and F28027
I'm going to bit-bang an ADS1100 using an TMS320F28027 but I'm not sure if the ADS1100 draws in current accordingly or do we need to limit the current of the signals, which should save battery power usage.
So the question is: do we need to put in resistors in between the I/O of the F28027 and the ADS1100? Or do we even need diodes?
Vortex Electrica Corp.
Sorry double posted.
If this is the only I2C device connected, you can break from the standard as there is no clock stretching/delaying feature with the ADS1100. The datasheet shows an example on page 13, figure 6 where the SCL line is tied directly to the controller. There is no internal pull-up on the ADS1100, so SDA must have a pull-up resistor. The reason being that when ACK takes place the ADS1100 will drive the pin low while the controller becomes the input. The SDA line on the ADS1100 is open drain, so to have the correct ACK/NACK there must be a pull-up on that pin. Values are typically 1k to 10k.
Thanks a lot for the reply. I'll get back to this post when I have more questions.
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