Altos Support

Introduction

Altos is a 8051 operating system for Altus-Metrum projects. The ChaosKey is a hardware random number generator that attaches via USB.

When the ChaosKey when inserted it appears as a device handled by the kernel with VID 0x1d50 and PID 0x60c6. If pins 1 and 5 are shorted as the device is connected then the bootloader is run, which presents VID 0xfffe and PID 0x000a.

The bootloader communication is not handled in the kernel, and a tty device is created so userspace can communicate with the hardware. Commands the bootloader accept are as follows:

List Information

Command: l\n Several lines of text about the device are transferred to the host, e.g.

altos-loader
manufacturer     altusmetrum.org
product          AltosFlash
flash-range      08001000 08008000
software-version 1.6.8

There doesn't appear to be any kind of end-of-message signal.

Read Flash

Command: R $addr\n where $addr is a memory address 0x8001000->0x8008000. 256 bytes of raw data are then transferred to the host.

Write Flash

Command: W $addr\n where $addr is a memory address 0x8001000->0x8008000. 256 bytes of raw data are then transferred to the device.

Application Mode

Command: v\n The device will reboot into application mode. This is typically performed after flashing firmware completes successfully.

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