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CAN in Space workshop

CAN substitutes Mil‑Std-1553B

About 80 participants joined the 3rd CAN in Space workshop organized jointly by ESA and Cobham Gaisler. The 3-day event took place in Gothenburg, Sweden.

The PicoskyFT fault-tolerant system-on-chip developed by Skylabs and presented in Gothenburg includes a CAN core and runs optionally a sub-set of CANopen (Photo: Skylabs)

In June, users and suppliers met to discuss made experiences and the future of CAN in satellites. Jeanluca Furano from ESA (European Space Agency) stated it his introduction that to test 20 000 lines of VHDL code requires less effort than to evaluate 1000 lines of C-code. Nevertheless, there is a trend to radiation-tolerant and radiation-hardened micro-controllers. Cobham Gaisler, one of the organizers of the workshop, presented in several presentations its products based on the GR716 mixed-signal processor and the GR740 quad-core fault-tolerant processor featuring CAN on-chip cores.

The planned Mars mission to be launched in 2021 makes use of CAN networks for different purposes (Photo: UAE Space Agency)

There was a debate on higher-layer protocols. ESA’s CANopen-based solution as specified in ECSS-E-ST-50-15C is one of the candidates, proprietary application protocols are the other option. What was clear in all presentations is the trend to use ISO 11898-2 compliant transceivers. Of course, they need to be radiation-tolerant. Cobham Gaisler, Microchip, and Renesas (formerly Intersil) showed their implementations. In the past, EIA-485 based transceivers have been used. For new design all satellites producers will implement radiation-tolerant CAN transceivers. Achmed Salem from the Mohammed Bin Rashid Space Centre in Dubai stated clearly that their satellites are going to be based on CAN networks. The made experiences in the already realized missions were very successful. In this year, a nano-satellite using CAN will be launched.

Attendees of the CAN in Space workshop (Photo: Cobham Gaisler)

CAN increasingly substitutes Mil-Std-1553B networks. But still there are legacy 1553B-based networks, so that CAN bridges are needed. The CAN networks use redundant bus-lines running often at 125 kbit/s or 250 kbit/s. Most of the reported use cases are telemetry applications. Some satellites implement 1-Mbit/s CAN networks. Of course, those networks are limited in length and number of nodes.

(Photo: Cobham Gaisler)

The workshop was accompanied by a tabletop exhibition. AAC Microtec, Cobham Gaisler, ESA, Kvaser, Microchip, Renesas/Intersil, and Skylab exhibited their products. The presentation slides are available online for the registered participants. Cobham and Microchip going to support CAN FD in their radiation-resistant processors. Additionally, first radiation-tolerant CAN FD transceivers have been launched. Of course, testing of radiation-tolerance needs to be finalized.