I have a Spark Fun Pro Micro (ATmega32U4) without a USB connection (it was broken off at an earlier point) that I want to use to duplicate a prototype running on another Pro Micro.
How can I upload a sketch to an Arduino without a USB connection?
2 Answers
The best solution is to solder back the connector or to buy a new board.
Ways to use a board with ATmega32u4 without USB for development are:
- ICSP programming
- upload over a serial bootloader.
Both require additional hardware.
For ICSP upload you need a programmer device. After configuring it, select the programmer in Tools menu and you can use "Upload using programmer" from the sketch menu. It is even possible to create a custom board definition which will use "Upload using programmer" with the "Upload" button from the toolbar.
To make serial upload possible you will need and USB-to-TTL-Serial adapter and Optiboot compiled for the 32u4. To burn the bootloader you will need an ICSP programmer or a second Arduino to use with the Arduino as ISP sketch.
Use a programmer, such as one based on CH341A that has pins broken out for CLK, CS, MOSI, MIOS [sic], GND, 3.3V, and connected those to pins on the Pro Micro as follows:
Programmer Pro Micro CLK-----------15 (SCK) CS------------RST MOSI----------16 (MOSI) MIOS----------14 (MISO) GND-----------GND 3.3V----------RAW
It doesn't appear that the programmer is supported in the Arduino IDE, so I grabbed chavrprog.
And ran the command $ sudo ./chavrprog -d mega32u4 -a s ~/Arduino/test/test.ino.leonardo.hex
- I see. The upload program implements the protocol. This is a very nonstandard solution for the problem in the question.2022-09-15 16:52:22 +00:00Commented Sep 15, 2022 at 16:52