Multi PCB, Hot Swap Unit: Looking for 8-12 channel ADC that communicates over USB

T

Treebeard

Member
Hi All,

I'm currently in the planning phases for a new project that is going to require hot-swappable PCB modules with various I/O on them: Some switches, encoders, screens, and I believe some sensors—the type are yet to be determined.

I was originally planning on using an ADS7138 <https://www.ti.com/lit/ds/symlink/ads7138.pdf?HQS=dis-mous-null-mousermode-dsf-pf-null-wwe&ts=1686623183076&ref_url=https%253A%252F%252Fwww.mouser.com%252F> so that I had 8 channels of I/O to communicate via I2C per PCB module, and I was planning on creating a hotswap buffer; however, the more I thought about this and asked around, the more I kept thinking that this would all be easier to do via USB than I2c.

By changing protocols, I will avoid a lot of headaches while simultaneously benefiting from the speed increase from I2C to USB.

With that out of the way, I have been looking to see what small form factor ADC's that offer USB, and I have more or less been coming up blank on anything attractive.

1) Is anyone aware of any 8-12 channel ADCs that happen to also communicate via USB out of the gate?

2) If not, what would be the recommended way of using something like the ADS7138 or equivalent ADC to then communicate over USB to the Teensy?

Thanks in advance!
 
Hmmm. It looks like my best bet is probably to use a USB to i2c bridge. It looks like there are plenty of decent options that can function as i2c masters, with a comfortable amount of GPIO available, which means there is more than enough expansion available for each module to have whatever i2c devices it may need.
 
Treebeard said:
Hi All,

I'm currently in the planning phases for a new project that is going to require hot-swappable PCB modules with various I/O on them: Some switches, encoders, screens, and I believe some sensors—the type are yet to be determined.

I was originally planning on using an ADS7138 <https://www.ti.com/lit/ds/symlink/ads7138.pdf?HQS=dis-mous-null-mousermode-dsf-pf-null-wwe&ts=1686623183076&ref_url=https%253A%252F%252Fwww.mouser.com%252F> so that I had 8 channels of I/O to communicate via I2C per PCB module, and I was planning on creating a hotswap buffer; however, the more I thought about this and asked around, the more I kept thinking that this would all be easier to do via USB than I2c.

By changing protocols, I will avoid a lot of headaches while simultaneously benefiting from the speed increase from I2C to USB.

With that out of the way, I have been looking to see what small form factor ADC's that offer USB, and I have more or less been coming up blank on anything attractive.

1) Is anyone aware of any 8-12 channel ADCs that happen to also communicate via USB out of the gate?

2) If not, what would be the recommended way of using something like the ADS7138 or equivalent ADC to then communicate over USB to the Teensy?

Thanks in advance!
Click to expand...

What do you want to do with the ADCs? Often with analog->digital conversion clocks and sample timing is important, and USB will provide a barrier to precision timing I fear.
If you go the USB route you need a USB capable microcontroller in every module, low level I/O chips are usually I2C or SPI or soe other simple hardware bus.

Maybe some more information about the overall application would be useful, otherwise the xy problem may be happening.
 
Ya, after reviewing my options, I just went with a STM32 chip. It pretty much has everything that is needed, and it avoids the exact issues you outlined, because those were giving me some anxiety.

Really, me trying to go the other route was an attempt to avoid prototyping with any SMT components for the time being, but that inconvenience isnt worth the nightmares it was producing.
 
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