MAX7219 voltage to low (0.2V)

schema

Hi,
What is the scope connected to?
What pins on the project?
What scope probe are you using?

Have you got gnd of the scope connected to gnd of the ESP32?

Show us a trace with the probe connected between gnd and 5V please.

Drop your timebase to 0.05s or lower.

Tom... :smiley: :+1: :coffee: :australia:

Scope is connected to Digit0 (Orange going out screen) and GND (white going out screen)
Scope is a DSO 112 A
GND of scope is connected to gnd of ESP32.

this is +5 and GND of ESP32.. is seems that you can also see the same rythm.

Hi,
What is your probe, is it a x10 probe.
Where is gnd level on your Scope screen.
The scope vertical scale says you are in 0.1V per division.

What brand/model scope is it?

Thanks.. Tom... :smiley: :+1: :coffee: :australia:

Hi Tom,

It is on x10, I can switcht it to x1.
I didn't know I had this switch! I used it, now my 5v looks like this:
5v:

And my digito0->GND :

This is what i have:

Hi,
Okay, good.
Your circuit at the moment is just a couple of LEDs connected to the 7219.

What scope pattern do you see on the output pins of the 7219 that go to the each LED?
What scope pattern do you see on the CLK input to the 7219?
What scope pattern do you see on the Din input of the 7219?
What scope pattern do you see on the Load input of the 7219?

Tom... :smiley: :+1: :coffee: :australia:

Your led labelled "nothing" should have it's anode connected to the SEG pin and cathode to the DIG pin.

It would be weird to wire the LEDs as shown in the max7219 data sheet?

DIG 0–DIG 7
Eight-Digit Drive Lines that sink current from the display common cathode. The MAX7219 pulls the digit outputs to V+ when turned off. The MAX7221’s digit drivers are high-impedance when turned off.
SEG A–SEG G, DP
Seven Segment Drives and Decimal Point Drive that source current to the display. On the MAX7219, when a segment driver is turned off it is pulled to GND. The MAX7221 segment drivers are high-impedance when turned off.

The sentence "On the MAX7219, when a segment driver is turned off it is pulled to GND" tells you why your "working" led turns on. That does not mean it's intended to work that way, it's just a side-effect.

Agree, paul!

But turning around the LED doesn't light up the "not working" led.
and I did buy "common cathode" 8 digit's elements. Which aren't working as well.

segment A:

Digit 0:

working led:

clk

Din
din

load:

I'm stil unable to figure this out. Can someone see my mistake?