mRPM

Maarten's RPM meter - arduino firmware

Introduction

The mRPM project uses the Arduino development tools to generate a firmware image for the ESP8266. This document explains how to install and use the Arduino tools to compile and flash from the sources. There is another document that explains how to use a pre-compiled binary and flash that.

The mRPM firmware consists of the following modules

• mRPM, the main program
• MAX7219_Dot_Matrix, a driver for the 4 x 8x8 dot matrix - by Nick Gammon
• bitBangedSPI, the SPI driver used by the dot matrix driver - by Nick Gammon
• a font for the matrix - by Nick Gammon, but patched

The latter three modules are written by Nick Gammon. Experienced Arduino programmers will store those modules in their library. For easy integration, they are copied into this project.

Note that the font has been patched. It contains 11 special characters: the digits '0' to '9' and the dash '-', all with a trailing decimal dot.

Steps

The instructions below show Maarten as user name (e.g. C:\Users\Maarten\Documents). Substitute your own user name.

Download and install Arduino for ESP8266

This project does not use a bare ESP8266 module; it uses an ESP8266 module on a so-called nodemcu board (basically adding a USB to UART bridge and a 5V to 3V3 voltage converter). This nodemcu specific instructables page is more appropriate than the official Arduino web page.

In either case

• Install the Arduino IDE.
• Add the ESP8266 compiler/libraries/examples. First in "File | Preferences | Additional boards Manager URLs" add http://arduino.esp8266.com/stable/package_esp8266com_index.json (with a comma if there are others). Secondly select "Tools | Board | Boards Manager" to get the Boards Manager, find esp8266 and click Install.
• Ensure that in "Tools | Board", the "NodeMCU 1.0 (ESP-12E Module)" is selected.
• Ensure that in "Tools | Port", the COM port for the ESP is selected.
• Get the blink example to work (this requires the ESP8266 board to be connected to your PC with a micro USB cable).
• Change the blink example a bit (e.g. make it blink faster) and save the (edited) blink project.

Typically the project is saved at C:\Users\Maarten\Documents\Arduino\Blink. Write down the root directory for the Arduino projects

C:\Users\Maarten\Documents\Arduino

Download and install this project

Follow these steps

• Download the zip of this project (press the green button on the home page).
• Open the zip, locate the directory arduino and within that the subdirectory mRPM.

  C:\Users\Maarten\Downloads\mRPM-master.zip\mRPM-master\arduino\mRPM
  

• Copy the mRPM directory to the Arduino project root.

  C:\Users\Maarten\Documents\Arduino\mRPM
  

Open, compile, flash

The ESP8266 board is assumed to be wired to the matrix and sensor - see wiring for instructions.

Next, follow these steps

• Double click the project C:\Users\Maarten\Documents\Arduino\mRPM\mRPM.ino to open it in the Arduino IDE.
• Ensure that in "Tools | Board", the "NodeMCU 1.0 (ESP-12E Module)" is selected.
• Compile it by pressing the Verify (green V in upper left corner) button.
• Ensure that in "Tools | Port", the COM port for the ESP is selected.
• Flash it by it by pressing the Upload (green right arrow) button.
• Quickly waive a white sheet of paper in front of the sensor. Its blue led should flash, and the matrix should show RPM numbers.
• On the ESP8266 board, press the small button labeled Flash (not RST) to change units.
• On the PC open the Arduino terminal to see the measurement process of the ESP8266.

You should now have this result.

Congratulations, you're done!

Implementation notes

There is a separate document with some implementation notes.

(end of doc)