The City College of New York
Grove School of Engineering
EE 22100-1BC Electrical Engineering Laboratory I
Spring 2016

Lab Report Experiment #7
Digital Clock

Instructor: Liang Yang
Student Name: Vivakeanand Boodhan
Partner Name: Mateusz Malinowski
Date Submitted: 05/16 /16
Objective:
The p urpose of this experiment is to learn how to use an LED Seven Segment Numerical D isplay and various types of integrated circuits (counters, gates, decoders) to design a 12 hour digital clock.
Technical Section /Procedure :
Connecting the BCD-to-Seven Segment Driver to the LED Seven Segment Display

center12065
Fig. SEQ Fig. \* ARABIC 1: Drivers connected to Seven Segment Display.00
Fig. SEQ Fig. \* ARABIC 1: Drivers connected to Seven Segment Display.
Figure 1 shows the wiring diagram for connecting the BCD-to-Seven Segment Drivers to the LED Seven Segment Display. As one can see, there are two drivers (one for each digit display). Pin 13 of the segment display is the common anode for the diodes of Digit 1 and while pin 14 is the common anode of the diodes for Digit 2 . Power is connected to Pins 13 and 14 so that the display can light up. Each Digit in display is made up of 7 segments (a-g) and so based on the logic coming in from the decoder, certain segments light up, hence, displaying a specific number. The decoders take in BCD inputs from the counters (will be discussed in next step) and decode the numerical value of the BCD. Pins 9 through 15 are connected to the segment display in such a way that the decoder can have BCD inputs for a specific number and the outputs connected to the segment display will display that number.

Connecting C ounter (CD4518) to Decoders (CD4543) for Seconds Display

center12700
Fig. 2: Counter connected to Decoders for Seconds Display.00
Fig. 2: Counter connected to Decoders for Seconds Display.

Figure 2 shows the wiring diagram for connecting the CD4518 counter to the decoders for the seconds display. The logic behind this schematic is that there is a clock input at Pin 1 which drives the counter. The second digit counts from 0 to 9 and the first digit counts from 0 to 6. When the second digit becomes 9 the first digit becomes 1 and so on until the seconds display shows 59 seconds. When the first digit becomes 6, the AND gate ands the 2 nd and 3 rd BCD inputs which in the case of the number 6 would both be 1 (6 in BCD is 0110). The output of this AND gate is connected to Pins 7, 9, and 15, and so after the first digit becomes 5 AND the second digit becomes 9 (making the seconds display 59), both digits are reset to 0.

Connecting Counter (CD4518) to Decoders (CD4543) for Minutes Display

center11430
Fig. 3: Counter connected to Decoders for Minutes Display.00
Fig. 3: Counter connected to Decoders for Minutes Display.

Figure 3 shows the wiring diagram for connecting the CD4518 counter to the decoders for the minutes display. The logic behind this schematic is that there is the clock input at Pin 1 is directly connected to the output of the AND gate described in Figure 2. Whenever the first digit of the seconds display becomes 6, the minutes counter (in Fig. 3) is enabled and counts up. Otherwise, the setup is much like that of the seconds counter.

-76200044767500 Connecting Counters (CD4510) to Decoders (CD4543) for Hours Display
12668253902710
Fig. 4: Counters connected to Decoders for Hours Display.00
Fig. 4: Counters connected to Decoders for Hours Display.

Figure 4 shows the wiring diagram for connecting the CD4510 counters to the decoders for the hour display. The logic behind this schematic is as follows. The clock input of both counters are connected to Pin 7 (or the output of the AND gate described in Fig. 2). The preset of the counter controlling Digit 1 is set to logic 0000 while the preset of the other counter (Digit 2) is set to logic 0001. The preset enable for both of these presets is controlled by the output of the AND gate (CD 4081) seen in Fig. 4. The AND gate ands the last two digits in the BCD that represents the