CP316: Microprocessor Systems and
Liquid Crystal Display (LCD) Prelab or
To be done in your lab notebook.
- Pin 3 on the LCD is the contrast voltage for the display. The typical circuit
uses a potentiometer wired as a voltage divider to allow the contrast voltage
to be adjusted. Normally, the circuit does not show a capacitor. The QwikFlash
board uses a fixed voltage circuit.
- Sketch the contrast voltage circuit for the QwikFlash board.
- At what voltage does the QwikFlash board have the contrast voltage
- Why is the capacitor there?
- Redraw the contrast voltage circuit to allow adjustment, i.e. using
- The Hitachi controller has a lot of different commands. How does it figure
out which command is being sent?
- The QwikFlash board ties the R/W line permanently low. With the R/W line
permanently at write, the read commands for the controller cannot be used
and all timing must be delay based. Using the timing diagram for the write operation
from either LCD manual or the text as a starting point, redraw the timing
diagram without the R/W line and remove all R/W associated timings. For all
remaining time intervals, write the actual minimum time (in ns) instead of
Demonstration - Explain your results for the above questions.
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