1. 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!

2. More circuit design Seven segment display

3. The Seven-segment Display Nothing more that 8 LEDs in a single package –Each LED can be turned on/off independent of all others

4. 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)

5. Schematic The schematic shows the part as seven separate LEDs (as expected)

6. Usage Use them as seven separate LEDs That is, for whatever you would normally use an LED for

7. Typical circuit schematic and layout See chapter 7 for example code –It’s just a bunch of OUTH and PAUSE statements

8. 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

9. 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

10. 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

11. 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)