DAC8750: DAC8750 crashes after a few cycles

Hi Melissa,

Does the output ever recover? Does any command work after the stop point? 

It is difficult to say if this a hardware or software issue.  You can check between a good command and an ineffective command?

Thanks,

Paul

Hi,

the output recovers after 350/400 cycles and crashes again after ~200 cycles.

after that it crashes completely. I have to reset the ciruit manually by turning DVDD/AVDD off and on again.

After the crashes I connected the DAC8750EVM with the test program.

It looks like this:

Setting any register isn't working.

Thank you

So it seems like all communication is returning 0xFFFF.  You could confirm with a scope that the SDO line is held high, or that the SCLK line is held low.  Does clicking the Reset DAC8750 do anything?

I think it is important to confirm if this is a software or hardware issue.  Once you are in the fault state, disconnect and reconnect the SM-USB-DIG from the EVM board.  While it is disconnected, power-cycle the EVM before reconnecting.  Does the software recover? 

Are you using the CRC functions? 

Do you have any read functions in your software? Can you try to read-back to the status register?

Thanks,

Paul

Hi,

clicking the reset button in this error state is not working. It writes 0x01 in the reset register but doesn't change the other registers.

If reconnecting the SM-USB-DIG with the EVM board & switching DVDD/AVDD off and on again, the software recovers most of the time (~75%).

Sometimes I have to restart the board about 5 times until the error disappears and the board is ready to work with.

If it's also of interest:

Working code from the day before, which was working completely fine for hours, suddenly isn't working anymore. I didn't change anything but the DAC can't be initialised.  

Does it look like a hardware fault?

I mean it's working for hours but suddenly not.

I'm not using the CRC functions. I can try it and show you the results.

Also I'll read the status register and post those results.

Thank you

I suspect this is a software issue.  You could try issuing a reset on the hardware while still using your code and see if the device recovers.  Really I think you need to confirm if the SPI data is valid at both points.

Hi,

sorry for the late answer.

the hardware recovers if I try to reset the DAC via the reset register. The data in the data register is valid.

But after a few cycles it still crashes...

I discovered it crashes if the output value is between 0x00AC (172) and 0x00BF (191).

Also I revised my spi connection. It's now like the DAC wants it ;)

Thank you very much.

Hi Melissa,

Is there any other communication on this bus? For example, are there other devices you are writing to?  I wonder if we are somehow getting into the CRC mode.  If you enter the CRC mode, then I think it would look like the bus is locked if there is not a valid CRC byte.  

This will be hard to confirm unless you can monitor the bus or you can actively implement the CRC mode and see if the issue goes away.  

Hi,

there is no other communication on the SPI bus.

I'll implement the CRC mode soon and let you know.

Thanks