User manual

LPCXpresso Experiment Kit - User’s Guide

Page 64

Figure 34 – Different LED Displays

7.9.1 Lab 8a: Test 7-segment Display

In this first experiment with a 7-segment display the microcontroller will not be used. We will only use

the LPCXpresso board to get the +3.3V supply. Verify that you can turn on each segment of the

display, by moving cables on the breadboard. The picture below illustrates the first breadboard setup

with the display. Note that the picture of the dual digit 7-segment display we have is not correct in the

picture below. In reality, the digits are turned 90 degrees and have two digits. There are however 10

pins on the component, just as shown below.

Figure 35 – Breadboard Connections for 7-segment Display Testing

Also verify that you can select with digit, of the two, to control. When working with digit #1, pin 9 shall

be connected to +3.3V and when working with digit #2, pin 4 shall be connected to +3.3V. Both pin 4

and 9 shall never be connected to +3.3V at the same time. When working with both digits they must be

time multiplexed. Half of the time, digit #1 is on and the other half, digit #2 is on. More about this in

later experiments.

7.9.2 Lab 8b: Control 7-segment Display

In this experiment you shall control one digit of the 7-segment LED display with the microcontroller. We

will use eight outputs to directly control each segment of the display. The anode of digit #1 will be

connected directly to +3.3V while the anode for the second digit is left unconnected. As we have done

before, the breadboard setup is prepared for the next experiments also. We will for example not use

the trimming potentiometer in this experiment.