Next Generation Mass Memory Unit (MMU-NXT)

The MMU (mass mem­o­ry unit) is a cru­cial com­po­nent in the data han­dling, pro­cess­ing, and down­link chain. In recent years, NAND flash mem­o­ries have become the dom­i­nant tech­nol­o­gy for large non-volatile stor­age, serv­ing as the foun­da­tion for mod­ern MMUs. NAND flash mem­o­ries offer sig­nif­i­cant stor­age capac­i­ties and fast read/write speeds for mass stor­age appli­ca­tions.

MMUs require the use of com­mer­cial-off-the-shelf (COTS) parts that must under­go screen­ing for suit­abil­i­ty in the harsh space envi­ron­ment.

The goal of the MMU-NXT study is to design a new archi­tec­ture for MMUs that improves data rate and stor­age capac­i­ty while slight­ly increas­ing size and weight. The increased capac­i­ty is achieved by uti­liz­ing state-of-the-art NAND flash tech­nol­o­gy with syn­chro­nous inter­faces.

The MMU-NXT archi­tec­ture con­sists of two main com­po­nents: the Com­mand and Con­trol Mod­ule for input, out­put, and mon­i­tor­ing, and the Mass Mem­o­ry Mod­ule (MMM). This sep­a­ra­tion allows for effi­cient han­dling of high data rates, which is achieved by incor­po­rat­ing state-of-the art FPGAs and Space­Fi­bre inter­faces.

In sum­ma­ry, the MMU-NXT will pro­vide the fol­low­ing per­for­mance:

• Aggre­gat­ed data rate of 20 Gbps
• Stor­age Capac­i­ty of 48 Tib­it
• 4 instru­ment Space­Fi­bre inter­faces (all active), oper­at­ing at 3.125 Gbps
• 2 down­link Space­Fi­bre inter­faces work­ing at 6.25 Gbps each for a com­bined data rate of 12.5 Gbps
• 4 SpaceWire inter­faces (all active), oper­at­ing at 200 Mbps
  
• 1 Wiz­ardLink inter­face, oper­at­ing at 2.5 Gbps
  

This sets the basis for the fol­low­ing func­tion­al­i­ties:

• recep­tion of data from one or sev­er­al pay­load instru­ments over medi­um or high speed links
• stor­age of the buffered data to flash mem­o­ry, employ­ing appro­pri­ate ECC schemes
• prepa­ra­tion of the retrieved data for down­link (CFDP PDU Gen­er­a­tor, TM Encoder etc.).
• trans­fer of the data to the pay­load data trans­mit­ter
• error man­age­ment of the NAND flash devices
  han­dling of telecom­mands, the col­lec­tion of house­keep­ing data, and the gen­er­a­tion of teleme­try