Using this as a serial console for an embedded system. The goal is to have the serial interface up and running before the embedded system boots so that the initial outputs can be captured. Don't want to deal with the console disconnecting when the embedded system reboots / gets power cycled.
The datasheet says to tie RESET to VIO, however, we don't want the CP2102 to reset when the embedded system is powered cycled. So our thought was to tie RESET to VDD. However this creates some odd conditions:
What to do about VIO coming up before VDD (if embedded system gets powered w/o a USB console plugged in).
VIO may not be present for some time and/or lost if for example the embedded system is powered off.
We've noticed periodically where the CP2102 USB side will not show any output until we disconnect/reconnect the device. It seems to be inconsistent so very hard to track down why the console output is lost sometimes.
Any ideas/feedback appreciated.
Hi Aaron Moore,
as far as I see . You can tie RESET to VDD without problem.
What to do about VIO coming up before VDD (if embedded system gets powered w/o a USB console plugged in):
VIO pin doesn’t power the device but it’s only used for GPIO pin. If USB console is not plugged in, the device is not powered up, meanwhile, GPIO pins are powered by VIO. That can make the system unstable.
I recommend you should tie VIO to VDD for stability. In this case you should use “level shifter” and pull-up resistor on RX pin for voltage compatibility.