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Reading 2 digit 7 segments with ESP32

StealthRT

Sep 4, 2010
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I have been trying to contact a forum member that has done a modification to his pool equipment in order to control it remotely instead of having to go to the box every time and check on the codes. His has released the source code on his github page.

However, I have a different model than he does so I do not think his ESP32 code will work on mine.

His equipment contains a TM1650 for the 2 digit 7 segment display. I am unable to find out if my version has the TM1650 or something else.

His schematic looks like this:



I have all the components that are displayed in the schematic. I have the ESP32 and the Level shifter.



Another forum member had the same chip but some pins were different. His schematic looks like this:

So, since I do not have the same setup as they do is there any IC I can get that would make reading the 2 digit 7 segments easier than trying to read each led and determining what letter/number is being displayed? I can use the 4n25/35 optocoupler to "press" any of the 6 buttons and have an analog read for the 8 LEDs to determine which ones of those are on. The only trouble I foresee is the 2 digit 7 segments reading.

Note: Also posted to the following forums:
Reading 2 digit 7 segments with ESP32
https://www.electro-tech-online.com/threads/reading-2-digit-7-segments-with-esp32.163357/
https://www.eevblog.com/forum/projects/reading-2-digit-7-segments-with-esp32/new/#new
https://www.electronics-lab.com/com.../48746-reading-2-digit-7-segments-with-esp32/
 
Last edited:

Harald Kapp

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Nov 17, 2011
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is there any IC I can get that would make reading the 2 digit 7 segments easier than trying to read each led and determining what letter/number is being displayed?
Very likely not directly as you want.
Besides, that is as far as I can determine not what the circuit you show does.

Have a look at the IC on the display pcb:
upload_2022-5-12_7-22-11.png
This ic is coonnected to the 7-segment display and is obviously the driver for the display.
It receives data via a serial interface (4-wire connection to the pcb), decodes this data into the 7-segment representation and displays it via multiplexing on the 2-digit LED display.
The circuit (and the accompanying code) attach to the serial interface to intercept the serial communication and do the decoding of the serial data on the ESP32. This is much easier than decoding the multiplexed 7-segment display data.

I have a different model than he does so I do not think his ESP32 code will work on mine.
Why not? The display seems to be the same. Give it a try.
 

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StealthRT

Sep 4, 2010
138
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So I'm looking at my version of the ESP32 that I have (Known as the Lolin32)
1652416286050-png.137070


And looking at their schematic I see that they call out GPIO 16, 17, 18 & 19. However, I do not have the same pin layout as they do...Go figure...
- GPIO 19 -> SWG main board clock
- GPIO 18 -> SWG main board data
- GPIO 17 -> Display board clock
- GPIO 16 -> Display board data
1652414673058-png.137068


So, I take it my layout would be:

GPIO 19 -> GPIO 19 MISO
GPIO 18 -> GPIO 18 CLK
GPIO 17 -> GPIO 17 TX
GPIO 16 -> GPIO 16 RX

That look correct?
 

Harald Kapp

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The important numbers are the GPIOxx ones.
The other labels are alternate functions.
The labels are irrelevant as long as the correct pins are used and controlled in HW and SW.
 
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