Anyone know the analog-to-digital resolution of the G3X Touch GP inputs?

[David Carter]

I'm interfacing a couple of different devices into the G3X Touch using the general purpose inputs on the GDU 4x0 and/or the GEA 24 to measure input voltages. What I can't find anywhere is documentation on the resolution of the G3X's analog to digital converters (ADC). The ADC resolution is defined as the smallest incremental voltage that can be recognized and thus causes a change in the digital output. It is expressed as the number of bits output by the ADC. For example, an 8-bit ADC has a resolution of 1/2^8, or 1 in 256, or 0.39%. With an input of 0-5V, the smallest recognizable change would be 5V/256 or about 19.5mV.

G3Xpert has been no help on this. Their response: "Sorry, we don't have access to any of that kind of detail for the system."

Does anyone know the answer, whether through documentation or experimentation?

Thanks!

 

[mburch]

If you can provide more details about what you are doing, it might be possible to offer an opinion.

 

[akschu]

I'm interfacing a couple of different devices into the G3X Touch using the general purpose inputs on the GDU 4x0 and/or the GEA 24 to measure input voltages. What I can't find anywhere is documentation on the resolution of the G3X's analog to digital converters (ADC). The ADC resolution is defined as the smallest incremental voltage that can be recognized and thus causes a change in the digital output. It is expressed as the number of bits output by the ADC. For example, an 8-bit ADC has a resolution of 1/2^8, or 1 in 256, or 0.39%. With an input of 0-5V, the smallest recognizable change would be 5V/256 or about 19.5mV.

G3Xpert has been no help on this. Their response: "Sorry, we don't have access to any of that kind of detail for the system."

Does anyone know the answer, whether through documentation or experimentation?

Thanks!

Pretty easy to figure it out. Get a 12-bit dac a 12-bit scope and increment tiny amounts while watching the config page for voltage changes. That should get you close, but If you are using this for something that has a scale like trim indication or a pressure, then I doubt it matters because I doubt the screen resolution is more than 8-bit.

 

[g3xpert]

Good Morning,

I think there was a misunderstanding of the question with our customer support team. To answer your question, you will not be limited by the resolution of the ADC of the GEA 24. While calibrating a GP input, you can specify voltages in increments of 1 mV.

Let me know if you have any other questions.

Thanks,

Justin

 

[David Carter]

Hi Justin,

I appreciate the response. 1mV resolution over a range of 0-40V (stated measurement range per 23.4.12 of installation guide Rev AU) equals 40,000 steps, requiring an ADC resolution of 16 bits. That seems unusual in my experience with hobbyist-level microprocessors. Can you please confirm that with the Engineering team?

Regards,
David

 

[David Carter]

If you are using this for something that has a scale like trim indication or a pressure, then I doubt it matters because I doubt the screen resolution is more than 8-bit.

This is a very good point that I had not thought about. Thanks!