Part Number: TMS320C6748
This pin is always reading 0, whether there is 0V or 3.3V on the pin or not, including when it is configured as an output and being driven high. When configured as an output, verified that the test point did toggle. When configured as an input, measured at the same test point when it was 0V and 3.3V, with the IN_DATA value not changing between states.. I have tried this on 2 boards with the same result. We have 15 other pins configured as inputs on our board design that have not experienced this problem, and I am quite confident in the register settings (PINMUX and GPIO), though they are included below for edification. Perhaps there is another register setting that needs to be configured for this specific pin?
I am not sure if there is something wrong with the DSP part, possibly an issue with this specific pin perhaps, or if there is a possible external schematic design problem that could cause the input to read as a 0 when a volt meter reads 3.3V. I have asked our electronics designer to have a look, but so far he hasn't been able to find anything.
Here are the register values:
Configured as an input, measuring 3.3V at the test point
PINMUX13: 0x88888888
DIR67: 0x001e8002
IN_DATA67: 0x000e0008
OUT_DATA67:0x38000008
Configured as an output, measuring 0V at the test point
PINMUX13: 0x88888888
DIR67: 0x001e0002
IN_DATA67: 0x000e0008
OUT_DATA67: 0x38000008
Configured as an output, measuring 3.3V at the test point
PINMUX13: 0x88888888
DIR67: 0x001e0002
IN_DATA67: 0x000e0008
OUT_DATA67: 0x38008008
I used a spare GPIO pin (GP3[12]) to verify that IN_DATA does toggle when the pin is configured as an output with different values driving it.