8452 master to TI 28xxx slave

[dave1111]

I can't seem to communicate to a TI piccolo (2806x) SPI slave bidirectionally (full duplex) in any of the 4 possible SPI modes.

The only way I can communicate is half duplex and to switch the 8452 clock phase to "second edge" when receiving data.

The TI clock phase is set to 1.

In the 8452 manual in section 1.8 it states "When the phase is 0, data is latched at the clock transition from
idle to asserted. When the phase is 1, the data is latched at the clock transition from asserted to idle."

Which data is it talking about, the MOSI or MISO or both?

I've attached a SPI timing diagram of the 2806x.

[robo_Jeff]

Hi dave1111,

Setting the phase specifies the latch for both MISO and MOSI. In which language are you programming? How exactly are you determing that full duplex is ineffective and half duplex is effective? Are you seeing a specific error? A screen shot of that error would be helpful.

Very important: do you have the latest driver installed? You can install it here. You need at least version 2.1.

Also, the link below may help. I know parts may seem elementary for you, but perhaps you will also find some useful information.

Using SPI with LabVIEW and the USB-8451 (relevant for the USB-8452 as well)

[dave1111 · Accepted solution]

Jeff,

I got it working by setting the clock phase on the NI adapter to one. What helped was the document link you included. That document specifies the clock edge at which the data is propagated.

i.e. "Data is also changed on a falling edge (high to low clock transition)."

The "NI-845x Hardware and Software Manual.pdf" does not specify this information.

Thanks for your help.

Dave

[robo_Jeff]

Sounds good, Dave. If you don't mind, go ahead and mark that as correct so the rest of the community can quickly find the solution.  

Have a great day!