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Expanding the BASIC Stamp: Useful peripherals Programming Unit, Lecture 6 LSU 06/04/2007 Expanding the BASIC Stamp 1 BalloonSat Expansion •The BalloonSat development board has basic features built-in but your application may require additional devices or circuitry or connection to external instruments. •The BalloonSat prototype area can accommodate temporary construction for experimentation and test. The prototype area may be large for payload specific circuitry and devices. •The P2 expansion connector allows easy access to the BASIC Stamp I/O pins, power and GND for external expansion. LSU 06/04/2007 Expanding the BASIC Stamp 2 Memory expansion with EEPROM •BalloonSat has one EEPROM chip installed. •Additional I2C EEPROMs can share the I2C bus (SCL and SDA). •Address bits (Addr2-Addr0) must be unique for each EEPROM added to avoid bus conflict. LSU 06/04/2007 Expanding the BASIC Stamp 3 Analog-to-Digital Converter •BalloonSat has an existing ADC. •More ADC chips can be added to prototype area or on external circuitry. •Devices may share SCLK and DO if each device has dedicated Chip Select (CS). Only one CS is enabled at a time. LSU 06/04/2007 Expanding the BASIC Stamp 4 Digital-to-Analog Converter •DAC7574 is one example of an I2C compatible DAC. •DAC7574 is a 4channel DAC with an analog output range of 0 to 5 volts. LSU 06/04/2007 Expanding the BASIC Stamp 5 Digital-to-Analog Converter DAC with output buffer for high-voltage and high-current load. •TBD LSU 06/04/2007 Expanding the BASIC Stamp 6 Digital I/O Pin Expansion •The PCF8574 I/O Expander features 8 additional I/O bits. •Expansion bits can be used as Inputs or Outputs. LSU 06/04/2007 Expanding the BASIC Stamp 7 Serial Communication Expansion •Some applications may require a dedicated asynchronous communications port. Payloads needing radio telemetry or connection to a GPS can use an added UART or USART such as the Maxim3100. LSU 06/04/2007 Expanding the BASIC Stamp 8 BalloonSat Expansion Precautions •The BalloonSat development board can be damaged by high voltages or reverse polarity. Make sure that any connections to the board do not expose BalloonSat to negative voltage levels or voltages greater than 5 volts. •Use caution when soldering in the prototype area. Do not accidentally short VCC to GND. •Turn the power off when making adding or removing components or wiring in the prototype area. LSU 06/04/2007 Expanding the BASIC Stamp 9
