Arduino Uno: How to reset the 328p via the 16u2?

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1

I'm using hoodloader2 to write a custom sketch onto the 16u2 (the chip that is normally used primarily as a USB-to-serial bridge) on the Arduino Uno.

Now, I'd like to be able to reset the Atmel 328p, and based on this diagram (1) pin "PD7" is the right pin on the 16u2 to pull low to get the 328p to reset.

However, when I pull that pin low, nothing happens. What am I missing?

Thanks!
Duane

(1) A diagram from the excellent "Arduino from Scratch" series: Arduino from Scratch Part 8: ATMEGA16U2 Subsystem

2

Thanks to help from timemage in IRC, I've discovered the issue: Pin 7 doesn't map to PD7 in hoodloader2's pin mapping of the 16u2: instead, it's pin 20.

See HoodLoader2/pins_arduino.h at master · NicoHood/HoodLoader2 · GitHub