Orbital Platform

Integrated flight systems board with flight controller, avionics & instrumentation, radio, science, and development support for UC Davis Space and Satellite Systems REALOP-1 mission.

Featured chips: (Many chips are removed for Revision 2. See below.)

• STM32L476ZGT3 (microcontroller)
• ASM330LHH (inertial sensor)
• QMC5883L (magnetometer)
• ADF7021 (radio front end)
• TQP7M9102 (power amplifier)
• SKY13453 (rf switch)
• MAX2208 (rf power detector)
• W25Q128JVSIQ (flash memory)
• MB85RS256B (ferroelectric memory)
• TMP235 (analog temperature sensor)

Documentation:

For an overview of the project, some FAQs, and links to some other documentation, see the Cattleworks Compendium

Other useful documents include

• STM32L47xxx reference manual
• STM32L476xx datasheet

Find flight software IntelliSat developed by the flight software team at the IntelliSat repository, including detailed documentation about widgets and connections.

toolchain:

For now we're using the Keil SDK for compiling the program, but the gcc-arm-none-eabi toolchain can also be used directly, with the flags (as used by Keil's invocation) -xc -std=c11 --target=arm-arm-none-eabi -mcpu=cortex-m4 -mfpu=fpv4-sp-d16 -mfloat-abi=hard -c -fno-rtti -funsigned-char -fshort-enums -fshort-wchar

The compiled program can then be uploaded over SWD using your software of choice.

Revision 2

Revision 2 hardware of Orbital Platform is in the verification stage. So far, so good!

Changes

• Removed radio system: communication function delegated to the new Orbital Imager
• Revised layout to improve routing, manufactuability, and reliabiltiy
• Inertial sensor (ASM330LHH) is now connected via SPI for reliability
• Magnetometer (QMC5883L) on its own I2C bus for reliability
• Addition of JST-GH connectors for
  • 6x Solar panels (photodiode + thermistor)
  • 4x Solar panels (pyramid design)
  • ESC control via PWM
  • ESC control via UART
  • Expansion UART
• Addition of pyrotechnic channel to drive antenna deployment meltwire
• Less LEDs (still a usable amount)
• Fixed EXTI pins: no overlapping signals
• Fixed USB FS implementation
• Design for manufacturability: reduced cost and BOM lines

Revision 3

Revision 3 is in the planning stage, most design choices are still undecided.

Some themes and guidelines for Revision 3:

• Keep software compatibility with R2. Remap a minimal number of pins and don't change existing peripherals.
• Further improve manufacturability.
• Include radio system (Orbital Imager will be deprecated)
  • Relatedly, we need a new camera interface port. Likely UART or SPI
• Possibly introduce additional features
  • More connectors: Coils, panel temperature sensors, etc.
  • More sensors: High precision temperature sensor, and digitizer for additional thermistors or sensors
• Mechanical adjustments to meet any changes to structures, and possible compatibility with High Altitude Balloon project
• Direct battery voltage measurement
• Current sensor and power switches for ADCS science and experiment payloads
• Another redundant set of avionics (IMU and mag) for good vibes. IMU does not need to be at dead center of board anymore
• Multiple connectors and associated pins for features like HDD-ESC and sun sensors
• Heart beat LED on PE2

Errata: a few things need to be fixed

• Re-pour copper planes to fix two shorted vias
• Correct the direction of the PMOS high side switch for the pyro/antenna deployment heater
• MCU ADC Vref needs to be tied to either 3.3 V or external reference

Related electrical team design tasks:

• Three channel constant current driver for magnetorquer
• Hard disk drive motor driver

Inter-board connector list for Rev 3

Mnemonic	Multiplicity	Connector type	Purpose
esc	1	?	HDD driver speed command and feedback
coil	1 (3 axis)	?	Magnetorquer driver control signal and I V feedback
sol	4-6	?	Sun sensor photodiodes and outer panel thermistors
mbat	1	JST-PH-4 (?)	Satellite main battery
cam	1	?	Imaging system data connection
pyro	1	JST-PH-4 (?)	Antenna melt-wire deployer
pv	4	?	Photovoltaic cell (solar panel) power input from each panel
inst	1-2	?	Auxiliary instrumentation bus (I2C) for remote ADCs
service	1	?	Ground diagnostic and firmware service port (SWD, UART)
topoff	1	?	Ground battery top-off charging port
rbf	1	?	Remove before flight safety interlock
aux	1-4	?	Auxillary UART/I2C/SPI ports
usb	1	USB Micro-B	Ground use USB port
trx	1	MMCX	Antenna coaxial RF connection to radio system

(Service and Topoff ports could be combined into "umbilical" port?)

Getting started

Orbital Platform should be delivered to you with a test program flashed, where it blinks the indicator LEDs in a demo pattern.

To program and debug the MCU, attach a SWD-compatible debugger like ST-LINK, JLINK, or DAPLINK, to the SWD connector near the MCU.

Label	Signal
3	3.3 V
G	Ground
C	SWCLK
D	SWDIO
R	NRST

The reset button is next to the SWD header, labelled RST.

Use your toolchain of choice to target the stm32l476zgt MCU.

Using the gcc-arm-none-eabi toolchain and pyocd with DAPLINK debugger

I personally prefer to use a very minimal environment for prototyping firmware. See the template project here

Using the Keil MDK (μVision) IDE with DAPLINK debugger

One toolchain that works with developing software for Orbital Platform uses the Keil MDK IDE and DAPLINK debugger dongle, on Windows.

• Start by downloading and installing a free version of Keil MDK-ARM (μVision). You should be able to download it after filling out some info on the download page
  • The free version now seems to be called "MDK-Community" and appears to be a non-commercial but fully featured version of the normal IDE. It used to be that the demo/eval/free version had a very restricted code size. Hope this is no longer the case.
• Also download and install STM32CubeMX which is ST's initialization code generator and graphical config editor. Scroll down on this page to Get Software. You might need to fill in some info for this as well.
• Launch the IDE.
• Find the "Pack Installer" in the top toolbar. It looks like a green diamond shape with four dots inside.
• Use the Pack Installer to install relevant CMSIS device support packs for STM32L4 Series
• Close Pack Installer. From the top toolbar, use the menu Project -> New μVision Project to start a new project.
• When given the option to select target device, choose STM32L476ZGTx
• When given the option to manage run time environment, enable CMSIS -> CORE, Device -> Startup, Device -> STM32Cube HAL. There may be dependancies highlighted in yellow, enable those too.
  • Also enable Device -> STM32Cube Framework (API) -> STM32CubeMX. If it requires you to press the button to launch CubeMX, do it. Try to proceed with default settings in CubeMX because we don't intend to use any generated code.
  • Don't enable anything else unless you want to use full HAL or other middleware.
• After creating a new project, open Options for Target in the top toolbar. Then go to the Debug tab and choose Use CMSIS-DAP debugger. No additional configuration should be needed.
  • Or choose whatever debugger you use, like ST-Link or J-Link.
• In the left side Project panel, right click Source Group 1 and select Add new Item to Group
  • Choose C File (.c) and name it main.c
  • You need to #include <stm32l476xx.h> to import register definitions.
  • Paste some code from this repository or write some blinky program.
  • Alternatively, you can git clone or zip download this repository and directly open the Keil project files. Everything should be configured for DAPLINK targeting Orbital Platform.
• Connect Orbital Platform to DAPLINK via the SWD port. Plug DAPLINK to your computer.
  • The DAPLINK should light up, if it doesn't, unplug it from your computer immediately and check your wiring. There may be a short circuit.
• Click Build on the top toolbar, then Download. Your code should now be compiled and flashed to Orbital Platform. Click Debug to launch the debugger, or signal a hardware reset to begin execution.