[Ground-station] 31 May 2018 IHU Meeting Minutes

Michelle Thompson mountain.michelle at gmail.com
Tue Jun 5 11:54:11 EDT 2018

A conference call was held on 31 May 2018. Presenting was Jonathan
Brandenburg, concerning his IHU project that he wishes to publish.

Open Research Institute will support publishing this open source Integrated
Housekeeping Unit (IHU) design intended for amateur radio satellite service
payloads. An IHU is a flight computer, controlling all the elements of the

The call was held courtesy of National Instruments conference bridge. Thank
you to Neel Pandeya for making it possible and for supporting open source
hardware and software designs.

The design team for this IHU consists of Zach Metzinger, Jordan Trewitt,
Bill Reed, and Jonathan Brandenburg. This started in earnest about a year
ago. It it not radiation hardened by design, but is entirely appropriate
for low earth orbit (LEO) use.

Initial design work was presented at the 2017 AMSAT Symposium.
This is a failover IHU design. It was two fault-tolerant processors. The
processor is TI Hercules and the part number is TMS570LS0914PGE. Each
processor has two cores, and each core operates in lock-step. There is some
flight heritage with this part from the ICI Radar Satellite and a NASA
Robotic ARM.

Included in the design are twin transceivers. The transceiver selected is
the AX5043.

A power amplifier design is in progress.
There is error correction on the memories.
This IHU has two “sides”, with one Hercules and one transceiver on each
side. There is diversity in the voltage regulators, with the primary side
powered by a MAX1556A regulators and a secondary side powered with
LTI963As. The diversity in voltage regulators is intended to provide
additional resilience. For each side, there is a 3.3volt rail and a 1.2volt

Software development has only just begun. Layout is approximately 80%

The board has 4 layers and relatively good power consumption based on
prototype measurement.

UPSat from Libre Space was also introduced and referenced.

OreSat is interested in collaborating and learning more about this design.

Our consensus is CANbus or Ethernet for flight hardware.

Jonathan has also made a Raspberry Pi daughterboard for the AX5043. This
allows development with the transceiver independent of the Hercules or IHU.

The drawbacks to the Hercules include terrible documentation and a
cumbersome parameterized code generation process for development. Jonathan
believes he is getting a handle on this and there is the possibility of him
producing improved documentation for this design.

We also discussed the VA10820 - Radiation Hardened ARM® Cortex®-M0 MCU
https://www.voragotech.com/products/va10820. This is approximately $700,
but has good stats and a well-documented toolchain. There is at least one
design that is open source that could be used as a basis for an IHU.

Jonathan to publish the IHU at https://github.com/phase4space/payload-IHU
Jonathan and Michelle to press for review of the design.

Michelle to publish minutes.

Michelle to arrange for additional IHU conference calls.

Microsemi’s SmartFusion2 and PolarFire devices were brought up outside of
the meeting.  They are actively advertising radiation hardening for these
parts and they may be available now and should be discussed.
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