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There are some digits missing in the PinLED Display
T
here are some digits missing on the PinLED Display. The CPU
board controls the digits of the PinLED Display. The signals come to the PinLED
board through J1 and J2. The Display is controlled from the left to the right.
That means that the first digit all the way to the left receive the first signal
from the CPU. The sixteenth digit all the way to the right receive the last
signal from the CPU. These 16 Strobe signals enable each digit to light at the right
time one after another. The digits of the first row and second row run
simultaneously.
How does this work with the display controlling? How can the
display spell the word "Hello" on the right hand at the upper row?
The strobes control each of the sixteen digits. Each digit receives its signal one after the other and then turns on. Strobe 1, strobe 2, strobe 3,.... strobe 15, strobe 16. After the last strobe it begins at the first strobe again.
If we want to write the word "Hello" the first 11 digits must be blank. That means at the time when the first 11 strobes ( strobe1 to strobe 11) come through, the signals to the segments of these digits have no information (all signals are low). At the time when strobe 12 is present the signals for the segments b, c, e, f, g, m are high and the letter "H" lights in the twelfth digit. After this the strobe 12 will go out and strobe 13 will come on. At the time when strobe 13 is on, the signals for the segments a, d, e, f, g, m are present and the letter "E" lights in the thirteenth digit. After this it will go on to the next digit and "L" will come on. Then the second "L" and then "O" at the end.
At the time then the strobes are running there is no information for the lower display row - the lower row is blank.
As I explained before the strobes are running one after the other - the display works in a multiplex mode. And if the strobes are fast enough the display does not flicker.
The following flowchart will help you to find the failure. It contains the information which IC's will work for each strobe.
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