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CaseCommander

Computer case environmental controller with USB control interface

Planned features

  • Fan speed control
    • Classic 3pin fans via variable supply voltage
    • PWM 4pin fans via direct PWM signaling
    • Various modes (static, threshold, curve, target [PID], TBD)
  • Temperature sensor readout and feedback
  • RGB LED strip control
    • SK9822 support
    • Various modes (TBD)
  • All functions should be inspectable and controllable from some form of PC (GUI) software

State of the art (as of 2020/06/16)

  • Design of supporting circuitry for variable voltage and PWM control is complete, yet to be tested and validated
  • Implemented firmware features:
    • USB communication
    • fan tachometer reading
    • SK9822 initial test implementation using SPI peripheral

Hardware

The chosen MCU is an ARM Cortex-M3 STM32F103C8, which is readily available from chinese resellers on a prebuilt board known as Blue/Black Pill.

There is also some supporting circuitry, consisting of a N-channel MOSFET (IRF3205 or IRF520N or equivalent) and gate driver (TC4420 or equivalent), one combo to drive each variable voltage control channel.

Development environment

Cross-platform? (Linux on Windows)

First try, Windows Subsystem for Linux: worked well up to the point of actually trying to flash the MCU -> WSL does not expose USB devices.

Second try, MSYS2: same issue as WSL.

My current environment is a Ubuntu 20.04 Server virtual machine which I SSH into from Visual Studio Code using its "Remote - SSH" extension (works really well). As a debugger probe I am using a SEGGER J-Link.

  • Ubuntu 20.04 with these packages: build-essential python-is-python3 libncurses5 (also openocd if you don't want to use proprietary software, but read on...)

  • Visual Studio Code with these extensions: C/C++, Cortex-Debug, Cortex-Debug: Device Support Pack - STM32F1

  • gnu-arm-embedded toolchain

  • J-Link Software for Linux 64-bit

    gnu-arm-embedded and J-Link software binaries paths must be set in the PATH (eg. by setting them in ~/.profile like so: export PATH=~/gcc-arm-none-eabi-9-2020-q2-update/bin:~/JLink_Linux_V680b_x86_64:$PATH)

As far as the debugging software is concerned, I first tried using OpenOCD (as you can see from the included debug launch configuration and openocd.cfg file) and it worked for simple flashing and debugging, but started crashing once I set up SWO trace in Cortex-Debug. The error was jaylink_swd_io() failed: JAYLINK_ERR_DEV_NO_MEMORY followed by a USB reenumeration of the probe and numerous other errors; I did not bother troubleshooting the cause (was it because it's running in a VM? who knows...), so I simply switched to SEGGER's official software, which is available and well supported for Linux.

Development utilities

JLink connections (SWD mode)

JLink Pin STM32 Pin
VTref 1 3.3V
GND 4 GND
SWDIO 7 PA13 34
SWCLK 9 PA14 37
SWO 13 PB3 39
nRESET 15 NRST 7

Used libraries

Building

  1. Clone repository including submodules

     git clone --recurse-submodules https://github.com/LaXiS96/CaseCommander.git
 cd firmware/

  2. Build libopencm3 (needed only once after cloning)

     make -C lib/libopencm3

  3. Build

     make

  4. Flash

     make flash

  5. Debug

     # Launch any "Cortex-Debug ..." configuration in VSCode
 # Configurations ending in "... Launch" will flash and reset the MCU; those ending in "... Attach" will simply attach the debugger without flashing nor resetting

Useful links