Download Introduction to Programming - Louisiana Space Consortium

The BalloonSat Development Board
Programming Unit, Lecture 3
LSU 2004
BalloonSat Development Board
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Background
•The LaACES BalloonSat Development Board evolved from CanSat,
developed by Professor Bob Twiggs at Stanford University’s Space
Science Development Laboratory.
•CanSat was designed to be accommodated within a soda can sized
satellite enclosure.
•CanSat featured a BASIC Stamp micro-controller, an additional
memory chip for data storage and a modem for connecting to an external
radio transmitter/receiver.
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BalloonSat Development Board
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From CanSat to BalloonSat
•ACES payloads did
not need the modem
of CanSat.
•No on-board
analog-to-digital
converter for
sensors.
•Expanding CanSat
with external
electronics was
inconvenient. LSU
designed add-on
prototype board.
LSU 2004
CanSat
BalloonSat Development Board
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BalloonSat Requirements
•LaACES BalloonSat designed to include
–BASIC Stamp micro-controller
–EEPROM memory for data storage and retrieval
–Analog-to-Digital converter
–Real Time Clock with provision for battery backup
–Prototyping area
–Expansion capability
–Suitable for laboratory activities, payload applications
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BalloonSat Development Board
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BalloonSat Features
•BASIC Stamp BS2P24
•24LCxx EEPROM
•Real Time Clock
•4 channel ADC
•V ref for ADC
•Temperature sensor
•4 LED indicators
•prototyping area
•expansion connector
BalloonSat
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BalloonSat Development Board
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BalloonSat EEPROM Memory
•24LCxx series CMOS Serial Electrically
Erasable Programmable Read Only
Memory (EEPROM) is supported.
•Synchronous serial interface, I2C
compatible.
•The 24LC64 provided is a 64K chip
organized as 8 blocks of 1K x 8-bits.
•Data retention of at least 200 years.
Erase/write cycles > 105
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BalloonSat Development Board
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BalloonSat Real Time Clock
•Dallas DS1302 Time keeping
IC.
•Synchronous serial interface.
•Registers for Year, month,
day, hour, minutes, seconds.
•Includes on-chip 31 x 8 bit
RAM for scratchpad data
storage.
•Low power requirements
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BalloonSat Development Board
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Analog-to-Digital Converter
•BalloonSat includes a 4 channel ADC, ADC0834
–MICROWIRE synchronous serial interface
•Precision voltage reference AD780
–Selectable 2.50 or 3.00 VDC reference for ADC
–On-chip temperature transducer
•On board operational amplifier for buffering and scaling temperature
transducer output.
•Temperature signal can be connected to ADC channel 3.
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BalloonSat Development Board
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Prototyping on BalloonSat
•Prototyping area features
GND and VCC busses.
I/O Pins
•Pads for BASIC Stamp I/O
pins P0 - P15
•Pad and bus layout is
compatible with DIP IC’s
(0.300” wide).
•GND and VCC testpoints
LSU 2004
Prototyping Area
BalloonSat Development Board
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Expanding BalloonSat
•Special applications may require interfacing BalloonSat with external
circuits or devices.
–An RS-232 device can be connected to the BalloonSat serial port.
For example, a GPS receiver. Not all devices will be directly
compatible with the BASIC Stamp. Level conversion circuits
might be necessary.
–BASIC Stamp I/O pins are brought out on expansion connector
P2 and on groups of pads at PL and PH for wire connections.
–Use of I/O pins must be planned to avoid device contention.
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BalloonSat Development Board
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Flying BalloonSat
•Flying BalloonSat in a student balloon mission requires some special
considerations not encountered on the lab bench.
–Battery power required
•Low temperature and pressure environment
•Suitable batteries for main power and for RTC backup
–Integrity of connections
•for flight applications, direct soldering of cables may be more
reliable than connectors.
•Jumpers should be soldered or secured in place.
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BalloonSat Development Board
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Activity P2
Students will complete the assembly of the BalloonSat.
Final inspection and voltage checks will be performed on
the completed BalloonSat.
Students will establish communications link between the
completed BalloonSat and the lab computer.
LSU 2004
BalloonSat Development Board
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