The firmware is written in AVR assembly language. It can be built for the ATtiny214, ATtiny414, and ATtiny814.
Building requires:
- ASAVR (part of the ASxxxx cross-assemblers package)
- GNU Make
- A Unix-like operating system (e.g. Linux, macOS)
Run make to produce Intel Hex files for the flash, fuses, and EEPROM:
make MCU=t414
If MCU= is not given, the default target is t414 (ATtiny414). Valid targets are MCU=t214, MCU=t414, and MCU=t814. It may be helpful to read the Makefile and the GitHub workflow.
MXLock has a dedicated header for connecting to an Atmel-ICE. It also has pins on its 2.54mm header that can be used to connect to a different UPDI programmer. In both cases, AVRDUDE 7.2 or later is used.
Connect the Atmel-ICE to the dedicated header on the MXLock board. Also connect a 5VDC power supply to the 5V and GND pins on the 2.54mm header. Install the Atmel-ICE drivers and then run make program, specifying MCU= if needed.
A SerialUPDI programmer can also be used. One can be made from an FTDI TTL-232R-5V cable and a 1KΩ resistor. Make the following connections to the MXLock board:
- FTDI RX → UPDI
- FTDI TX → 1KΩ resistor → UPDI
- FTDI GND → GND
A 5VDC power supply must also be connected to the MXLock board. The 5V pin on the FTDI cable may be used as the power supply.
Since macOS and most Linux distributions ship with built-in FTDI drivers, drivers are not normally required. Run make program and use ISPFLAGS= to set the SerialUPDI options for AVRDUDE:
make program MCU=t414 ISPFLAGS='-c serialupdi -P /dev/cu.usbserial-FTABCDEF'
The above command will flash an ATTiny414 using SerialUPDI on port /dev/cu.usbserial-FTABCDEF.