This is the C3 (Command, Communication, and Control) card for OreSat. It acts as the central control point for the entire OreSat project, provides telemetry to the ground, and receiver commands. It's the "on board computer" (OBC) of the OreSat bus. It has:
- Octavo OSD335x-SM SIP AM335X-based Cortex A8 Microporcessor
- On Semi AX5043-based L Band (1.265 GHz) receiver
- On Semi AX5043-based UHF Band (436.5 MHz) receiver and transmitter with 1W PA.
- Custom radiation tolerant watchdog timer based on the TI TLV1042 comparator.
- 16 GB eMMC flash data storage
- 1 Mbit of FRAM for high reliability state and variable storage
- Supercapacitor-backed up RTC
- Two antenna deployment circuits
- OreSat Power Domain (OPD) control circuitry
Design materials are on Google docs; we'll post links / PDFs soon.
Bill of Materials (BOM) can be found here.
Fixes for the radio receivers, version 2 backplane pinout, and lots of little tweaks after our lessons learned on OreSat0. OH, and a COMPLETE REFACTOR since we switched from the STM32F439 to an Octavo OSD335x-SM and switched from EAGLE to KICAD. Yikes.
The C3 runs Python code that interacts with the radios, peripherals, and CAN bus. Here's more information.
C3 V5 flew on Oresat0, Oregon's first satellite! Everything worked great, except for the radio receivers (L band LNA oscillated, and UHF LNA was turned off in firmware).
The firmware for the C3 card is written in C and runs on top of ChibiOS, a small RTOS. It is integrated into the oresat-firmware repository. The firmware application for this project is located here.
C3 V4 is our latest version of the C3 card; it's getting ready for flight in Q2 2021 in OreSat0. It's got all of the functionality necessary for flight.
The 2018-2019 ECE Capstone brought the card to version 3. It implements an STM32F446VET6 IC, the full L band receiver with ultistage LNA, and a UHF radio with LNA but no PA for transmitting.
Most embedded project starts out as a bunch of development boards strung together; the C3 is no different! The breadboard prototype for the C3 card implements an STM32F446RE development board connected to two SPI radios, the OreSat FlatSat backplane via a CAN transceiver and I2C for the OPD interface, and a SDIO and SPI connected SD/MMC Card. The breadboard implements stronger pullups for the I2C lines than the GPIO of the STM32 can provide. It is currently capable of interfacing with and activating the OPD connected boards.
All materials in this repo are copyright Portland State Aerospace Society and are licensed under the CERN Open Hardware Licence Version 2 - Strongly Reciprocal (CERN-OHL-S v2), or any later version. A copy of the license is located in here.