Driving 53 LEDs for a nice boost gauge

Projects General Guidance
1

Hi,

I have an AEM wideband exhaust gas gauge in my car and it looks good. I also have an AliExpress boost gauge, which sucks. Or blows, depending on the boost. But either way, I want to change the boost gauge for something better. I have an empty AEM gauge housing and I want to make a PCB fitting that housing, with a pressure sensor and a lot of LED's, like the AEM WB gauge.

For the value, the gauge gets a lot of LEDs:
1 for the dot between the first and second digits, when in bar mode
1 for the dot between the second and third digits, when in PSI mode
1 for a minus, in the settings I want to be able to chose relative or absolute pressure
3x 7 for three digits
In the AEM gauge, as in my design, all LEDs are directly mounted to the PCB and the light is shining through holes in the face plate.
The ring of LEDs around the edge of the gauge face consists of 25 more LEDs.

The three digits I can each give a 74HC595 7-segment driver.
The dots and minus I think I should drive direct from the Arduino.
The outside ring, I hope to find an IC (or multiple 'in series') that can be run with only a few Arduino outputs.
I plan on using a MPXH6400AC6T1 as pressure sensor and maybe put in a light sensor to control LED brightness. It should be able to run in four modi;

  1. in bar, absolute
  2. in bar, relative (so below zero when not in boost)
  3. in PSI, absolute
  4. in PSI, relative (so below zero when not in boost)
    With a simple push button to scroll throught the modi.

For the Arduino itself, I consider the Nano. I hope to desolder the processor with the bootloader already on it and resolder it on my board. My board should contain all parts the Nano board does.

Anyway, that's the plan, please advise about the ICs and about the Arduino board / processor. I also consider to go full ATmega2560 on the board, and drive each LED individually.
Thanks,

Hugo

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Unless you really have a need for an ATmega2560 I would think about using an ATmega328P common Arduino UNO. Why? Since once you load your program and have things all working on a breadboard it's a one and done. You can buy the 328P chip and 28 pin dip socket for under $10 USD. I would just buy an Arduino UNO board with an extra chip and socket. Use the chip and socket on your board. Unless you are well setup for removing and replacing SMT chips I would avoid it at all cost. :slight_smile:

As to display? You may want to just consider a LCD display like this one. You only have 4 lines, Vcc, Gnd, SCL and SDA.

Ron

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A MAX7219 matrix chip can drive 64 LEDs, and has a brightness pin.
They are frequently used behind 7-segment displays, up to eight digits per chip.
Leo..

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@Ron_Blain; thanks for the reply. Your suggestion might make sense, but it is not the chosen route and does not lead to the desired result.

@Wawa; thanks, that is exactly what the doctor ordered. My knowlegde of parts is too limited, with this chip and Google it makes sense.

Cheers,

Hugo

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