I2C and static digital IO on AD3

[EVC]

I am developing a PCB of a test setup based on AD3.

I am using I2C to control a couple of I2C I/O expanders to control relays (lots of them).

There are a few other devices (relays, LEDs, switches etc.) that I was thinking of controlling through the digital I/O signals. I found a recent thread with a similar use case. That user, though, was trying to use the DigitalOut functions and I understood it is not possible using both, protocol and Digital[In/Out] because of resource conflicts.

I only need static I/O and, one of the answers by @attila suggests that it should be possible using DigitalIO:

Quote

You can use the digital-io functions to control the DIOs.

 

I implemented two small classes in python to perform the i2c and DigitalIO functions I need, and I have run a few tests. In a very similar way as user @liu, I can have the object instances of either class to work separetely, but when I create the i2c object and then the DigitalIO object, this latter breaks the former (it returns "NAK -1").

 

Looking at the pdf version of the reference manual, I found this:

Quote

The digital IO signals are shared in the device between Digital-IO, Out and In functions. The Digital-IO has priority over Digital-Out. The Digital-Out is only applied for a signal when the Digital-IO Enable and Output are zero for the respective bit.
 

 

I obviously made some mistake as the statement above is not entirely clear to me. Is there an example or code snippet that I could use as a basis to allow me to use both I2C and DigitalIO without conflicts?

 

Thanks in advance.

 

[attila]

Hi @EVC

You can use freely use the FDwfDigitalIO functions to control DIOs, just make sure not to override the SCL/SDA DIOs used by the FDwfDigitalI2c or FDwfDigitalOut functions. So, if SCL/SDA is DIO 0/1 then for digitalio function make sure the output enable and value with do not control 0x0003, like mask it with 0xFFFC, DIO 15:2

 

[EVC]

17 hours ago, attila said:

So, if SCL/SDA is DIO 0/1 then for digitalio function make sure the output enable and value with do not control 0x0003, like mask it with 0xFFFC, DIO 15:2

 

Hello @attila, first off, thank you for your prompt response. It turns out I was writing ones to the I2C DIOs as I assumed only the bits set by FDwfDigitalIOOutputEnableSet would be altered.

Thank you very much for your great support.