Vlad, i have all 6 displays of the MCP connected using your guides, i managed to get IAS/MACH SPD and ALTITUDE working correctly, the others (Both Courses, HDG and VertSPD) just show 0.0.0.0.0.0.0.0

They are wired exactly as the ones that work (Altitude and IAS) they have power cause the red numbers light up but they show only "zero". i didnt put any offset , they are with the standard configuration.

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May 31, 2019 in 7-Segment Displays by

2 Answers

Hi Hernan,

I had the same problem in the beginning.
Do you have the resistors (120-300 ohms)
on the address bus and on the "T", "D", "L" and "S SIG" lines?
7Seg- board resistor to "CLK / Gnd"? That was the problem for me. Properly connected it works great.
Please check this documentation https://simvim.com/svc_structure.html and https: //simvim.com/svc_numbers.html

Frank

														
May 31, 2019 by

Hernan,
You said you have all "0.", maybe it's all "8." ?
1. Check the signal (CLK on MAX7219) wires again
2. Make sure you don't have the "ground loops" for Mux and displays.
3. Use a pull-down resistor for CLK, as described (especially if you have long and crossing wiring.

Note: In my "test panel" I don't have any pull-down resistors for 4x 7-segment displays and all works fine (because of correct and clean wiring)

Another note:  Don't use Pin #13 for inputs, use it for outputs only.

Vlad

May 31, 2019 by

You said you have all "0.", maybe it's all "8." ?
Yes, it's all "8"

1. Check the signal (CLK on MAX7219) wires again,
All seems to be good

2. Make sure you don't have the "ground loops" for Mux and displays.
I have all GND to common GND BUS

3. Use a pull-down resistor for CLK, as described (especially if you have long and crossing wiring.
See my  photos:


https://drive.google.com/file/d/1wJ-HtEKittnWxKdo7xAKkFp7tyBHz_qb/view?usp=sharing

https://drive.google.com/file/d/1NkvqD-WjRLEDG83rgCOkynUxmdbNjh7B/view?usp=sharing

I found the error, it turns out that 3 of the 6  MAX displays had a poor welding and the pin was making a bad contact, also one cable from the signal bus was broken. I changed the MAX displays welding the male pins better this time, changed the broken cable and problem solved, thank you
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