Pulling DTR down after closing Serial Monitor

Projects Networking, Protocols, and Devices
1

Not sure if this is the right subheader to post this under, but here goes.

I'm using an I2C multiplexer with the Adafruit Flora to send signals to 7 haptic motors. Everything works fine when it's first uploaded and when the serial monitor is open. However, after opening the serial monitor, if I close the monitor the I2C signal is highly delayed and my motor actuation timing is completely off.

I noticed on the COM port that the DTR signal is not being pulled back down to low after the monitor is closed, and was wondering if there's a hardware or software fix for this. The Flora doesn't have a reset pin for me to connect with a resistor, just the reset button, which I imagine would be a pain to solder off. Is the SPI reset pin on the Flora also a reset pin for the board? That would be much easier to access. In terms of software, is there a way to change the port configuration such that the DTR gets pulled back down automatically, say with python?

2

As the Adafruit Flora is ATmega32U4 based it probably includes the Leonardo code. You can remove the DTR dependency by changing the bootloader and CDC code but you'll loose the possibility to upload code by USB. If the DTR changes the USB code does a soft reset and waits for new code to be uploaded. Of course the usual functionality pauses in that time.