As I reported in my previous column, I was recently invited to attend the first SpacE FPGA User Workshop, or SEFUW for short. This was held at the European Space Agency's ESTEC site in Noordwijk, Holland.
The workshop involved the ESA (European Space Agency) and the major FPGA manufacturers of space-grade devices. Also attending were industrial and academic partners working with FPGAs in space or working toward enabling FPGAs to be used in space.
The event was split into two days -- the first covering European FPGAs and the second focusing on non-European devices. Both days involved presentations from manufacturers on roadmaps for their devices and presentations from actual users reporting on their experiences with the devices.
Day two of the workshop was dedicated to non-European FPGAs, which meant that the focus was upon Microsemi and Xilinx. It is these FPGAs -- especially the ones from Microsemi -- that have a significant heritage in space and are used in a large number of space-related designs.
In August 2012, the Curiosity rover landed on Mars.
The first presenter of the day was from Microsemi. This speaker started by addressing the existing RTSX-S/SU and RTAX-S/SL/DSP families, with which most people present were familiar. These are radiation-tolerant antifuse-based FPGAs that feature radiation-hard flip-flops, thereby removing the need for user TMR (triple modular redundancy) in most applications. (TMR refers to using three copies of a functional element or system and then voting to determine the result.)
As the RTSU is the smaller and older of the two families of devices, questions were asked about their suitability for use in new designs. It was confirmed that these devices would be available for a number of years to come as the silicon manufacturer still supports the 250nm process node.
Focus then shifted to the newer RTAX-DSP and RT Pro ASIC3 devices. The RTAX-DSP is a modification to the RTAX2000 and an RTAX4000, which removes a small number of flip-flops and replaces them with radiation-hard multiply accumulate blocks (64 in the RTAX2000D and 120 in the RTAX4000D). It seems that at least two customers are currently designing the RTAX2000D into their projects, although these products have yet to launch and gain the all-important heritage. The RTAX-DSP devices also have been subjected to modifications to the registers to harden them against Single Event Transients (SETs), thereby allowing high-speed shift registers to have better radiation performance than can be achieved with the traditional RTAX devices.
The RT Pro ASIC 3 was the subject of much discussion as -- being Flash-based -- it allows the design to be changed all the way up to launch. This obviously has several benefits, including the fact that it is expensive to program additional OTP (one-time programmable) devices, and the fact that there is risk of damaging the PCB when an OTP component is removed and refitted. While in-flight reconfiguration is theoretically possible, Microsemi does not recommend this at this time as the programming circuitry is still being validated. It is hoped that this device will achieve full QML-Q qualification in early 2013, having already achieved MIL883B.
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