Apollo is the on-board debugger and programmer on Cynthion. It is used to load gateware over USB onto Cynthion's FPGA. Alternatively it may be used as an on-board or external debugger for certain other FPGA platforms.
Apollo consists of two main parts: firmware for the on-board debug microcontroller and Python-based software for the host computer.
To install the apollo-fpga Python module and the apollo command-line tool or to upgrade them to the latest version run:
pip install --upgrade apollo-fpga
To upgrade Apollo firmware on a Cynthion it is typically not necessary to compile the firmware yourself. Instead follow Upgrading Cynthion Device Firmware.
To compile and install onto Cynthion run:
$ cd apollo/firmware
$ make APOLLO_BOARD=cynthion get-deps dfu
This will download dependencies, compile the firmware, and install it onto Cynthion with Saturn-V.
Alternatively you can use variables to specify an older hardware revision:
$ cd apollo/firmware
$ make APOLLO_BOARD=cynthion BOARD_REVISION_MAJOR=0 BOARD_REVISION_MINOR=3 get-deps dfu
Once installation is complete, LED A should activate, indicating that Apollo is running.