Is there a way to automate a reset using a USB to UART bridge if it's connected to a Raspberry Pi

I am trying to design a circuit for a new sensor board which essentially uses UART comms but I want to incorporate the option for USB to allow you to use a USB cable from a Raspberry Pi USB host to the sensor board.

But if I'm using USB I don't have access to the Raspberry Pi's reset pin via the USB cable. This is no problem if the Raspberry Pi powers up, but that is no good if the Raspberry Pi reboots. I would like to have it that if the Raspberry Pi reboots, my sensor board will do so too.

To simplify the design and testing process I am using one of these breakout boards: www.adafruit.com/.../5335

This uses a CP2102N and breaks out DTR, RTS, CTS etc etc. So I have options.

But I don't have any ideas... hence the question

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0 shabaz over 1 year ago in reply to BigG

The CP2102N is possibly a mask-ROM microcontroller, and it is configuring the pin as an input with pulldown as one of the first things at startup perhaps. But it's very, very unconventional to try this; each CP2102N might have a slightly different resistance, and other USB-UART chips might do something different. I think here be dragons down this path : (
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0 BigG over 1 year ago in reply to shabaz

Ah, yours are wise words that come from those scars called experience :-)

So whilst somewhat unconventional, I'm thinking that this might work as the host cannot mess with the signal and in this case I'm working on the basis that I will also be using a known peripheral, namely the Adafruit CP2102N and my sensor board.
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