command and data handling
DESCRIPTION
Command and Data Handling. Li, Michael Jayaraman, Vijay Bhatia, Vishal Winkelman, Martin. Introduction. Command and Data Handling subsystem is responsible for computing and control of subsystem functions. - PowerPoint PPT PresentationTRANSCRIPT
DINO Peer Review April 19, 2023
Command and Data Handling
Li, Michael
Jayaraman, Vijay
Bhatia, Vishal
Winkelman, Martin
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Introduction
• Command and Data Handling subsystem is responsible for computing and control of subsystem functions.
• The core of this subsystem is a single-board computer powered by the Intel PXA255 Processor.
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Design Requirements
• C&DH must not exceed 7 Watts.• Maximum ½ kg.• External watchdog timer.• External reset.• 3.8” x 3.6” x 4” minimum profile• Must run Linux• 32MB RAM minimum• 8MB FLASH minimum
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Interfaces
Subsystem Requirements
COMM• 1 dedicated RS-232 serial port to TNC.• 1 RS-232 serial port to initialize radios.
Science Two USB ports for cameras.
ADCS 9 channel ADC (12-bit precision minimum)
Tip-Mass 1 RS-232 serial port for RF module.
Structures13 binary inputs to monitor states of certain deploymentmechanisms
Power 1 R-232 serial port
Thermal 32 channel ADC for thermistors
Software Kernel, BSP etc…
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Arcom Viper
• PXA255 400Mhz CPU• SDRAM: 64M• FLASH: 16M• 256K Battery Backed SRAM• Real-Time Clock• Watchdog Timer• Interfaces:
– 2 USB v1.1– 5 Serial Ports– Compact Flash Drive Support– Ethernet: 10/100BaseT– JTAG– 8 GPIO– PC/104
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Power Consumption
PartPower Consumption
(Watts)
Flight Computer 1.6
Wireless Interface 2.4
Miscellaneous Interfaces 1(max)
Total 5 (max)
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Specifications (Viper overview)
Power Requirements:
• 1.6W @ + 5V only supply (typical)
• 200mW @ +5V (standby mode)
Operating Temperature:
• -20°C to +70°C
• -40°C to +85°C (extended)
Form Factor: PC104
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Design Options
• MIP405
• RPXLITE
• VIPER
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OPTIONS CONSIDERED
Option 1 : MIP405• Integrated embedded IBM PowerPC processor • 375 DMIPS at 266MHz or PPC405GPr with 608 DMIPS at 400MHz• Power consumption Typically < 5.0 Watts• Ethernet, USB and 128MB SDRAM
Pros• 128MB on-board soldered SDRAM (ECC support), up to 4MB on-board soldered
Flash. • SRAM, EPROM, Flash and Disk-On-Chip modules can be added for keeping a
redundant copy of the Flight Operating System as a back up in case of failure.
Cons• Higher power consumption. • Doesn’t come with pre-loaded version of RedBoot Linux !!
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OPTIONS CONSIDERED
Option 2 : RPX Lite• Integrated single-board computer based on the Motorola MPC823 version.• Capable of providing the user with a bandwidth of up to 80MHz. • Mechanical specifications of the PC104 standard• 32, or 64 Mbytes SDRAM16• 2, 4, 8, or 16 Mbytes Flash• 0, 32, 128, 512 Kbytes NVRAM/RTC• SCC2 - 10BaseT (RJ-45) Ethernet port
Pros• The Dino team could get some help from the 3CS team as this has been
previously used in the 3CS project.
Cons• Processor speed – 80MHz. Much less compared to the Viper.• Cost Per Unit ~$900. Much more expensive compared to other SBCs.• Poor technical support.
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Reasons For Design Decision
• Ultra Low power consumption of 1.6Watts. • Has most number of Serial ports as compared to the other boards.• Provides 8 General Purpose I/O pins with expansion possibilities.• Meets all interface and design requirements.• Good processing speed of 400MHz.• Low Cost – Only $400!!• Lead Time of around 1-2 Weeks.• As the board is pretty new, it would be easily available in the market
until Dec 2005.• Dr. Sam Siewert and his team of researchers from the ECE
department (CU) are using the same Viper board in their research. He would be a great source of information regarding Viper incase the C&DH team needs his advice
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Other Unexplored Options
• EBC-C3 Winsystems SBC up to 700MHz via Eden processor.
• SAT-520PLUS Winsystems SBC featuring 133MHz processor.
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Testing PlansUART TEST – TX/RX verified on a terminal
Ethernet controller test – try pinging an IP address on the same network and say one IP outside the network (proposed to be used when we run short of the serial ports esp. for debugging and loading code on to the board…)
RAM test – try writing all 0s and all 1s and read them back. Try writing alternate 1s and 0s and try reading back and verifying the data
Flash test – similar to the RAM test.
Test with the actual viper board. test with a potentiometer which varies the voltage to the A/D converter.
JTAG Interface can be used to troubleshoot system hangs
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Testing Plans (cont.)
• Test individual I/O pins.• Test USB – Probe bus and detect cameras• Test FPGA - Assert certain pins, test schematic.• Radiation Tolerance tests (industry supported?)
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Budget
Component QuantityUnit Price
Total Price
Flight Computer 2 $410.00 $820.00
Interface Board
However many fits on a sheet ~$200.00 ~$200.00
Board Support Software 1 $1000.00 $1000.00
A/D board 1 ~$100.00 ~$100.00
Total: ~$2000.00
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System Block Diagram
Flight Com puter (Arcom V iper)
Intel 400 MHz PXA255 XScale
Current/VoltageMonitors for Mechanism
Deploym ent
PC/104 PC/104
ADCSSensors
InterfaceBoard
Therm alSensors
(~32)
A /D ConvertersPC/104 TTL D igital I/O
USB (2) Reset Serial Ports
FPG A(Reset Logic)
PowerSubsystem
Tip MassRF Module
Radio/TNC(2 COM)
Science(Cam eras)
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Thermal Interface
Sensors in different parts of DINO
Temp. Sensor
Flight Computer
ADC
Sensor select for temperature reading
MUX
Digital Temp. readings
select
Temp. Sensor
+5V
10k
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Temperature Sensors
Temperature-controlled Variable Resistor
Voltage proportional to temperature change
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Watchdog and Reset Decoder
• Built-in watchdog on Viper
• Reset decoder will be implemented in FPGA