PGA302EVM-037: GUI OWI Data Monitoring

Hi William,

We currently do not have any plans to add OWI data monitoring to the PGA302 GUI. Your best bet for monitoring OWI would be to measure the UART-level OWI TX and RX signals (available on J12) using a logic analyzer rather than measuring the VDD directly.

Regards,

Scott

Hi Scott,

My question refers to using the OWI interface vs using I2C to due calibration using the PGA302EVM-037 platform. I get this message when trying to do data monitoring with only OWI connected to my off board device. I am using the PGA302EVM-037 without the socketed PGA302 and breaking out to my sensor board using only OWI, VDD and GND. I would prefer not to have an additional I2C connection on our production boards. This will allow us to configure completely packaged sensors via 3 wires. If this can't be done using the current eval board and GUI, please confirm that it can be done by us in a custom application using only OWI.

Thank you

Hi William,

For calibration it is still possible to use the "PGA302 Linearity Calibration" page with the OWI communication, or the Memory Map page to directly read the ADC values. Is there a reason that the Data Monitor page specifically needs to be used?

Regards,

Scott

Hi Scott,

Thanks for the quick replies. I have several different sensors that I need to set up the AFE on. I've just found it easier to use the data monitor to set my gains. Since those shouldn't change once they're determined, I can use the Memory Map page or hook up the I2C on some of my prototypes. Down the road we will want to automate this. Do you have any idea when the documentation and/or source on the EVM firmware and GUI DLLs will be available?

Best regards,

Bill

Hi Scott,

I've been doing some more testing using OWI. Actually, I can't get it to work at all with I2C disconnected. Just to rule out my board, I removed the I2C leads from a PGA302 and placed it back into the EVM socket. Other than power and USB, nothing else is connected to the EVM. Once USB communications are established I get this:

I power up the OWI Interface...

When I select OWI for the Communication Interface, this message pops up for 5 minutes...

Followed by this...

I checked the VDD with OWI_5P5 set HIGH, VDD = 5.22V This is as low as I can set it. From data sheet min high threshold is 5.3V

OWI_5P5 set LOW, VDD = 4.58V, DS threshold low 4.7V

Following these tests, I replaced the EVM PGA302 with a new part with all leads intact. Now when I select OWI for the Communication Interface, the GUI pauses then appears to establish communications. I'm reading non-zero values out of the registers, but don't know if it's actually using the OWI.

Thank you,

Bill

Hi Bill,

When you attempt the OWI communication can you monitor the VDD with an oscilloscope and share the activation pulses and first command that it sends?

Thank you,
Scott

Hi Scott,

I didn't have time to send you plots of what I see. What I saw with the I2C connected part: setting the Communication Interface to OWI and manually sending a VDD Activation Pulse both sent activation pulses, With the part with the I2C leads removed, I would only get activation pulses when manually controlling in OWI Settings, nothing when I switched the Communication Interface to OWI. I hope this helps. I won't be back in till Monday. I'll get you some captured data then if you would like.

Thanks,

Bill

Hi Bill,

Thanks, that's essentially what I was looking for. I'll have to do a little testing on my end to see if I see the same thing. I'll get back to you next week.

Regards,

Scott

Part Number: PGA302EVM-037

Hi Bill,

I was able to test the EVM in the way you described and I’m actually not seeing the same behavior. I lifted the I2C pins on a PGA302 device in the socket on the EVM, and I was able to initiate OWI communication both with the manual activation and by switching to OWI communication in the top panel. The GUI starts up just as described, with the I2C showing as disconnected, but OWI seems to work just fine.

If you are using an external board to connect to the VDD pin on the EVM he will likely need to adjust the R21 potentiometer to make sure that the VDD voltage at the PGA302 on his board is in the correct range for proper communication. Just measuring at the output of the EVM will not work unless it is directly tied to the VDD pin on the PGA302 on the separate board.

Regards,

Scott

Hi Scott,

I will try that when I resume testing in a week or so. I will verify all the states on the OWI line. This also failed when I placed a device in the EVM socket with the I2C pins removed without my board. However, I may have some other issues with my PCB connected to the EVM through a 1m cable length. I'll let you know what I find.

Best Regards,

Bill