Why can't I use IO 39 like I can use the rest of the DIO?

[Alejandro-Dev]

I will soon start using more of the digital IO pins for a project so I was testing them out. They all seemed to work fine except for IO 39.

I am testing the pins with I2C protocol, like so:
 

dwf.FDwfDigitalI2cSclSet(hdwf, c_int(13))
dwf.FDwfDigitalI2cSdaSet(hdwf, c_int(14))

Using number 15 (DIO 39) in either function will result in error but the rest of the IOs are working fine.

I tested this in two diffeent DDs and got the same results. Is this an expected behaviour? Am I missing something?

[attila]

Hi @Alejandro-Dev

With clock stretching option enabled only the first DIOs can be selected and all these will be used/driven for I2C state machine.
For Digital Discovery with 32Ki sample Pattern Generator buffer the first 15 DIOs, for Analog Discovery with 1Ki the first 10 DIOs... can be used
Without FDwfDigitalI2cStretchSet any DIO can be used.