last week’s project demos servo control with photoresistor and enable/disable buttons demo in...
TRANSCRIPT
Last week’s project demos
• Servo control with photoresistor and enable/disable buttons
• Demo in class tonight – don’t start on the next project until I’ve seen this one!
More circuit design
Seven segment display
The Seven-segment Display
• Nothing more that 8 LEDs in a single package– Each LED can be turned on/off
independent of all others
The Seven-segment Display
• Like individual LEDs, each has a cathode and an anode leg
• The anode of each LED is routed to its own pin on the package
• All cathodes are connected together and routed to two pins on the package (choose one of the other)
Schematic
• The schematic shows the part as seven separate LEDs (as expected)
Usage
• Use them as seven separate LEDs
• That is, for whatever you would normally use an LED for
Typical circuit schematic and layout
• See chapter 7 for example code– It’s just a bunch of OUTH and PAUSE statements
Memory usage
• So far we have been writing to individual pins on the Basic Stamp module
• For the seven segment display it would be convenient to write to multiple pins at one time
• The I/O pins are memory mapped to various PBASIC Word type instructions – INS, OUTS– These are broken down further to Byte type instructions
• INL, INH, OUTL, OUTH (Low byte, High byte)• These are broken down further to Nibble type instructions
– INA, INB, INC, IND, OUTA, OUTB, OUTC, OUTD– These are broken down further to Bit type instructions
» IN0 – IN15, OUT0 – OUT15
• Utilizing these instructions will set the direction of the pin accordingly
Memory usage
• Another instruction called DIRS (and all size variations) is available to set the directions of the I/O pins
• We saw this earlier when we needed to “disconnect” an output pin– Set the bits to 0 for input direction– Set the bits to 1 for output direction– Default power up is input
• This is useful when setting up to do I/O without actually doing the I/O operation
Homework
• By changing the value of the capacitor the time decay can be altered
– Book labs had you do this
• For this assignment
– Build RC circuits using both 0.1uF and 0.01uF capacitors to create 2 timers (select one resistor value)
– Include a button to select one of the two timer s• Include debug statements to indicate timer decay
– Use the bidirectional LED to indicate which timer is selected
• Green – fast (short time decay)
• Red – slow (long time decay)
– Include a 7-segment display in your design in some creative way
Deliverables
• Due next week– A functional description of the system– A state-machine diagram depicting the
operation of the system– Source code– A schematic diagram of the circuit– A working demonstration on the Basic
Stamp development board (in class)