- Mon Sep 05, 2016 5:44 pm
#54573
Here's a truth table for the nodemcu reset circuit, straight from the nodemcu schematic:
As you can see, reset and gpio0 remain high as long as RTS and DTR are the same - regardless of whether they're both high or both low.
On the board I tested (A WeMos D1 Mini, with a non-FTDI usb-serial chip) I found RTS and DTR were low when I first plug in, and when the Arduino serial console is running; whereas both RTS and DTR are high when I close the Arduino serial console, power the module from a 5v usb power bank, or run the module on 3.3v with the USB disconnected. Presumably there's some careful toggling of RTS and DTR during programming to trigger the bootloader properly.
cems wrote:I wish I understood why the transitor flipflop method doesn't mess up when you open a serial monitor.
Here's a truth table for the nodemcu reset circuit, straight from the nodemcu schematic:
As you can see, reset and gpio0 remain high as long as RTS and DTR are the same - regardless of whether they're both high or both low.
On the board I tested (A WeMos D1 Mini, with a non-FTDI usb-serial chip) I found RTS and DTR were low when I first plug in, and when the Arduino serial console is running; whereas both RTS and DTR are high when I close the Arduino serial console, power the module from a 5v usb power bank, or run the module on 3.3v with the USB disconnected. Presumably there's some careful toggling of RTS and DTR during programming to trigger the bootloader properly.
