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Old 04-21-2021, 07:50 AM   #2
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bobxyz's Avatar
Join Date: Aug 2014
Location: Boulder CO

Hi Diego, Wow, you've done a lot of work! Very nice.

A couple years ago, I started to work on a similar project to monitor LH2.4+EZK using a simple Arduino board. I wanted
- a dashboard Multi-Gauge LCD display for use while driving, and
- full speed logging for offline tuning and graphing

At the time, I was only monitoring the EZK signals, plus a Wideband O2 input and a MAP pressure sensor input. This is what my benchtop setup looks like, with a couple different displays (click pictures for bigger size).

The items shown are:
- Load - the width of the ECU Tq Load signal in microseconds (proportional to injector on time)
- Vbat - battery voltage
- Idle - the TPS idle switch
- DegF - the coolant temperature, currently the raw ADC value, not yet converted to degrees
- AFR - Wideband O2
- Spk - spark advance in degrees
- Dwel - spark dwell time in milliseconds
- KpA - input from MAP pressure sensor (currently connected to pot for testing)

For testing, I have a LH2.4 ECU and a EZ116K connected with a chopped off harness to a simple engine simulator board. The switches are for some of the sensors (temperature selects 3 resistors -- normal, hot, cold), and the one knob is for the MAF (or AMM) voltage. RPM (60-2 wheel signal) is from my Hantek oscilloscope pattern generator.

To connect to the EZK signals, I soldered wires to the connector pins inside the box. I think this will work in the car, but it's not pretty.

After working on the project for a while, I ran into some problems:
- The Arduino Nano that I was using didn't have enough pins to monitor EZK+ECU and support a LCD display
- Updating the LCD display (over SPI) was much slower than I liked.
- The LCD library (Adafruit GFX) occasionally glitched when sharing the Arduino with my interrupt-based measurement code. I think this is a common problem for Arduino libraries, that they don't work well with other interrupt based libraries.

I got busy with other projects and this one has been gathering dust for at least a year. With your inspiration, I've started to work on the project again.

Instead of using a single Arduino to do everything, I want to change the architecture to use 2 Arduinos. One would do all the measurements and only use a simple serial port interface. This can be connected to a Bluetooth module for logging and display on a PC or smartphone. If I can figure out the protocol, and there are not any legal issues, it would be nice to support TunerStudio or MSdroid software applications. For the in car dashboard multi-gauge, a 2nd Arduino and a small LCD display would be used, with a serial interface to the 1st Arduino.

I need to work through the available pins on an Arduino Pro Micro (32U4) to see if they can monitor all the ECU, EZK, and extra signals that I want. I'll post a pin usage proposal when I'm done.

In Italy, what hobbyist PCB companies do you have access to? There are a couple Chinese companies that are now offering PCBs plus assembly with common surface mount parts. Can you get PCBs from or

'85 245glt b21ft aw71 k-jet -> lh2.4
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