As part of the hackaday.io Everyday Carry contest that I am (in part) building the bag movement alarm for, I need to utilize a Trinket Pro. Which is fine, because the product itself is a pretty affordable ~$10, and it packs pretty much to same punch as an Arduino Uno.
I ordered one from the hackaday store, and it was delivered decently quickly (and came with cool graphic mask as you can see). It came without headers soldered on, and given my previous experience, I soldered them right on, including a short two pin header on the A6 and A7 pins (the location of these two pins is inside from the edge, and as a result when in a breadboard these two pins will be the same as A0 and A1. In a perf board, these could be separate).
The challenge was programming it.
There were three challenges:
1) Adding the Trinket Pro as an eligible board. I needed to download the boardfile from Adafruit, and extracted to a folder that I put in the my Arduino folder (end result: arduino/hardware/Trinket Pro/boards.txt).
2) Utilizing the USBtinyISP driver to install via the USB drive (instead of the FTDI header). I tried downloading the driver from Adafruit and installing it on my Windows machine, but it would not install. The install window would just flash briefly and then disappear, as if there was nothing install. I tried several times. Luckily, I also have an old MacBook Pro which already has USBtinyISP installed. So, instead of using my Windows machine, I needed to transfer files to my MacBook and then I could program the TrinketPro. It also labeled the serial ports differently than on my Windows machine: instead of “COM6” etc., it used “/dev/cu.Bluetooth-PDA-Sync”.
3) Timing the programming. The TrinketPro requires that you press the reset button to put it into the bootloader mode, and then you have window of time to upload a new program before is goes into running the current program on the board. I found that if I pressed the reset button on the TrinketPro and then pressed the upload button on the IDE, the compile would take too long and the bootloader would exit before the uploading began. I needed to press the upload button in the IDE on the computer, wait a second or two, and then press the reset button on the TrinketPro to get into bootloader mode. If I did that, the sketch would upload successfully!