alt Hacker NewsThe teensy is so weird though. At least back when I played with them. They put a secondary chip which let's you flash over USB but they cover the debug pins and the only way to get serial over the USB port is to have a whole USB stack as part of your application. As a development board I would rather go with one of those STM32 backed boards and a knock off STLink, you need the STLink to flash, if you want DFU you can add that yourself, and you get a debug adapter.
Could you clarify what you mean about getting serial over the USB port in the context of debug pins?
I've been using Teensy devices for over a decade and have always had it just recognize the device as if it were a USB to serial adapter and I can talk to it as what I'd call "serial over the USB port". But that obviously doesn't involve what I think software people usually mean when they're talking about firmware debug -- which usually entails stepping through execution, right?
I'm used to just printing debug statements to the Serial.println() function, I learned on the 8051 where the best bet was to toggle different pins when code lines are passed, so even Serial.println() was a huge step up.