# PD Buddy Sink Firmware This is the firmware for the [PD Buddy Sink][], a smart power jack for USB Power Delivery. The firmware is written using [ChibiOS][] RT and HAL, and is comprised of a [library][] for USB Power Delivery and an application using that library to request a configured voltage and current. [PD Buddy Sink]: https://git.clayhobbs.com/pd-buddy/pd-buddy-sink [ChibiOS]: http://www.chibios.org/ [library]: lib/README.md ## Features * Two boot modes, Setup and Sink, selected by the Setup button's state at startup. * Sink mode implements a simple USB Power Delivery sink, aiming for full compliance with the USB Power Delivery Specification, Revision 2.0, Version 1.3, and with Revision 3.0, Version 1.1. * Requests the configured voltage and current if available, or a safe, low power request otherwise. * Provides power on the output connector only when an explicit contract is in place for the configured voltage and current. * Optional GiveBack support allows power supplies to temporarily remove power from the PD Buddy Sink if necessary. * Requests can be made from programmable power supplies, allowing voltages to be requested at 20 mV increments from a wide range (up to 3-21 V). * Configuring a voltage range provides a fallback if the preferred voltage is unavailable. * The amount of current the device requests can be set as a power or a resistance, as well as a current. These values are taken as constant over the configured voltage range. * Setup mode implements a USB CDC-ACM command-line interface, compatible with Linux, Mac OS X, and Windows 10, allowing configuration to be loaded from and stored in flash. * Setup mode allows real-time renegotiation of voltage and current, complete with the ability to control whether the output is enabled or disabled. * Users can easily read a power supply's advertised capabilities while in Setup mode using a [PD Buddy Wye][]. * Firmware upgrades are easily possible via Setup mode in conjunction with the microcontroller's built-in DfuSe bootloader. [PD Buddy Wye]: https://git.clayhobbs.com/pd-buddy/pd-buddy-wye ## Prerequisites To compile the firmware, you must first install the [GNU ARM Embedded Toolchain][toolchain]. Details of its installation is beyond the scope of this README. Once the toolchain is installed, clone this repository with: $ git clone --recursive http://git.clayhobbs.com/pd-buddy/pd-buddy-firmware.git This will give you a complete copy of the repository, including the ChibiOS submodule. You will also need to install some program to flash the firmware. The simplest option is [dfu-util][], as it requires no extra hardware (though if upgrading from versions older than 1.2.0, either the Boot switch must be installed or two pads must be bridged). If you prefer to use SWD, you could also use [stlink][] or [OpenOCD][]. [toolchain]: https://launchpad.net/gcc-arm-embedded [dfu-util]: http://dfu-util.sourceforge.net/ [stlink]: https://github.com/texane/stlink [OpenOCD]: http://openocd.org/ ## Compiling With all the dependencies installed, the firmware can be compiled as follows: $ cd pd-buddy-firmware $ make This compiles the firmware to `build/pd-buddy-firmware.{bin,elf}`. ## Flashing The firmware can be flashed in any number of ways, including but not limited to the following: ### dfu-util To flash via DfuSe (ST Microelectronics's extended version of the standard USB DFU protocol), the Sink must first be put into DFU mode. If upgrading from a version older than 1.2.0, or if no firmware is installed, set the Boot switch (SW1) on the PD Buddy Sink to the position not marked on the silkscreen to set the device to DFU mode. If your Sink doesn't have a Boot switch installed, you can simply bridge the two pads of SW1 circled in [this image][dfu pads] with a blob of solder to achieve the same effect. Once this Sink is set to DFU mode, plug it into your computer. If upgrading from firmware version 1.2.0 or later, you can easily enter DFU mode by running the following command from the Sink's configuration shell: PDBS) boot This immediately puts the Sink in DFU mode until it is reset or unplugged. When the Sink is in DFU mode, the Status LED should be glowing dimly. The firmware can then be flashed with: $ dfu-util -a 0 -s 0x08000000:leave -D build/pd-buddy-firmware.bin If applicable, don't forget to set the switch back to normal mode (or remove the solder blob) after unplugging the device. [dfu pads]: docs/dfu_pads.jpg ### stlink If you have an ST-LINK/V2, you can use it to flash the firmware via SWD as follows: $ st-flash write build/pd-buddy-firmware.bin 0x8000000 ### OpenOCD OpenOCD can also be used to flash the firmware. If your debug probe is an ST-LINK/V2, you can easily do this as follows: $ make flash-openocd-stlink ## Usage After first flashing the PD Buddy Sink, the device has no configuration. To configure it, plug it into your computer while holding the "Setup" button. The LED should blink once per second to indicate that the device is in configuration mode. There are then two ways to configure the Sink: a serial terminal, or the configuration GUI. ### Configuration with the Serial Terminal Connect to the PD Buddy Sink with your favorite serial console program, such as [GNU Screen][], [Minicom][], or [PuTTY][]. Press Enter, and you should be greeted with a `PDBS)` prompt. The `help` command gives brief summaries of each of the available commands. For example, to configure the PD Buddy Sink to request 2.25 A at 20 V, run the following commands: PDBS) set_v 20000 PDBS) set_i 2250 PDBS) write When `write` is run, the chosen settings are written to flash. You can then simply disconnect the Sink from your computer. For more information about the serial console configuration interface, refer to [the full documentation][shell docs]. [GNU Screen]: https://www.gnu.org/software/screen/ [Minicom]: https://alioth.debian.org/projects/minicom [PuTTY]: http://www.chiark.greenend.org.uk/~sgtatham/putty/ [shell docs]: docs/console_config.md ### Configuration with the GUI The Sink can also be configured by the [PD Buddy Configuration][pd-buddy-gtk] GUI. For more information, see that repository's README. [pd-buddy-gtk]: https://git.clayhobbs.com/pd-buddy/pd-buddy-gtk ### Using the configured PD Buddy Sink Once the Sink has been configured, just plug it into your USB PD power supply. If the supply is capable of putting out the configured current at the configured voltage, the Sink will negotiate it, then turn on its output and blink the LED three times to indicate success. If the supply cannot output enough power, the Sink will turn its LED on solid to indicate failure, and leave its output turned off. ### Status LED descriptions LED State | Mode | Meaning ---------------------|-------|--------------------------------------------------- Fast blink (4/sec) | Sink | Negotiating USB Power Delivery contract Medium blink (2/sec) | Sink | USB Power Delivery contract established, output on Off | Sink | Output on On | Sink | Unable to get configured power from source Slow blink (1/sec) | Setup | Running in setup mode Fast blink (4/sec) | Setup | `identify` command run