On board computer

Data Processing Unit (DPU)

The DPU handles every action onboard the satellite.
The satellite system unit onboard the Munin satellite is a slightly modified spare model of our instrument from the microsatellite Astrid-2. The heart of the unit is a Texas Instrument TMS320C50 signal processor.

The processor has 20 kb of internal memory and runs at 40 Mhz clock frequency. To the processor we connected 16kb of external RAM, used as program memory, 64k word EPROM for flight software and 32 k word EEPROM for various data and software patches. The PROMs are only powered at bootup and when onboard software patching is needed.

We have 2 Mb of RAM for data storage. This is used for instrument data, packing and buffering (FIFO) the data before downlink.

The DPU controls all the instruments, including switching and monitoring power and collecting and processing instrument data.

A 10-bit A/D converter is used for monitoring satellite status such as temperatures, battery- and solar cell -voltages and -currents, etc.

The DPU is communicating with the radio transceiver through the specially dedicated DSP (digital signal processor) modem. It will receive commands and transmit scientific data and satellite status. It is also possible to upload program patches when the satellite is in orbit.

There is also standard functions as real-time clock, watchdog etc. Much of the electronics is realised in Actel PLD„s (Programmable Logic Devices).

Icon of TI-symbol

Press the Icon to wiev a rendered picture of the DPU„s sensor interface.

Contact person for on board Computer is: Jonas Olsen

IRF - RYP - SwRI - Luth