ADS7047: Troubleshooting ADC Devices

Abe,


The methodology that you mention certainly helps. Checking the reference voltage and the digital I/O are going to help debugging the device. However, there are a few things that I would add.

In some devices, there are registers that require programming, I would always make sure that you can program them and read them back. Also some devices power up with actively making conversions and will have a /DRDY pin that you can see that the conversions have completed. If the device has these features, they do help in debugging. Unfortunately, the ADS7047 doesn't have either of these features.

What I think really helps is using a logic analyzer to view the digital communication and verify timing. Making sure that the microcontroller puts out what you think it should is one of the best debugging tools to have. Many questions that I see posted here can be answered with a quick look at the digital communication waveforms.

Another troubleshooting tool is putting in a known voltage and reading back the correct voltage. Often you can debug problems by putting in several known voltages and read back the resulting data. Often posts in the forum will say that the resulting data is garbage, but more often than not, it is a problem in the readback that causes data to be altered in a specific way. If you can figure out the ways that the data is being jumbled, you may be able to solve the communication problem. Again, this is also something that a logic analyzer can help with.

Regardless, it just helps to play with the device in different ways and observe the changes. There isn't a set way to troubleshooting ADCs, but it does help to try different things.


Joseph Wu