ECE 367 Experiment 5: Time-Multiplexed Seven Segment Displays, Lab Reports of Microprocessors

Download ECE 367 Experiment 5: Time-Multiplexed Seven Segment Displays and more Lab Reports Microprocessors in PDF only on Docsity! ECE 367 - Experiment #5 Time-Multiplexed Dual Seven Segment Displays Spring 2006 Semester Introduction This experiment requires that you construct a circuit interfacing the MicroStamp11 module with two seven segment displays, and write assembly language code to drive them in time-multiplexed fashion to display a count of seconds and tenths-of-seconds. Required Hardware In addition to the MicroStamp11 module, this experiment requires two seven segment LED displays, two TTL hex inverters (one 74LS04 IC) and the 220Ω DIP resistors. Wiring Diagram Build the following circuit on a solderless breadboard – the circuit is very similar to that in Experiment 4. PA6 is an output-only pin, and all the other lines from the micro- controller must be configured as outputs. Except for their common-cathode inputs, the two seven segment displays are wired in parallel (a to a, b to b, etc.): Both inverters must be included in the circuit. Inverter #1 buffers PA6 from having to sink up to 7 LED on-currents; without it the microcontroller would be damaged. Inverter #2 acts as a decoder to select which of the two digits is active according to the state of PA6.
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   a b c d e f g a b c d e f g a b c d e f g a b c d e f g CC CC 
 seconds digit tenths-of-seconds digit 1 2 When PA6 is high, data appearing on the a-g segment lines will be displayed on the seconds digit. When PA6 is low, the tenths-of-seconds digit will be on. You may wonder – how then may we display both digits at the same time? We don’t. When rapidly displaying one digit and then the other (repeating this at about 100 cycles per second) the human eye perceives both digits to be on. Thus, at the cost of only one extra output line, we have added another digit to the display from that in Experiment 4. For your reference: Sample circuit layout for Laboratory Experiment #5. a b c d e f g g f CC a b e d CC c dp dp