My customer is using TMS320F28388. They used GPIO as input port. Customer is wondering what will happened if they short this GPIO to one of analog pin of the C2000?
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What is their reason for shorting the digital input signal to an analog pin? Are internal pull-ups disabled on the IO? They'll be in a HI-Z state (floating input) if not.
The additional digital input connection to the ADC input will add some capacitance on the sampled signal due to trace length and device IO parasitics.
I have learned that the I/O buffers have the highest leakage when mid-biased. i.e if you place 1.5V instead of ~3.3v or 0v, the I/O buffer draws higher leakage current (pin and supply). This may not be an issue for the customer's application if power consumption isn't a big concern however.
Thanks a lot for your additional information. For example, customer wants to use GPIO for Trip zone to use. This pin can also mux to the analogue input. Thus, they need to placed these two pins short to different pin on C2000. Based on my understanding, it should be OK
For example, customer wants to use GPIO for Trip zone to use.
Customer can use the device's analog comparators for this actually, then they only need the analog pin connection. There are connections from the CMPSS to the ePWM module for this.