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Overview

The V0.1 board was the first hardware implementation and is not intended for general in car use. It does however drastically simplify testing on stationary engines.

Layout

The board is a 2 sided 'shield' that is approximately the same width as an Arduino Mega, but extends out at both ends. It has I/O for all the main sensors as well as 4 channels each of ignition and fuel.

Populating the board

The following components are needed to fully populate the board:

  • R1, R2, R3, R5, R7, R7 = 10k Ohm resistors
  • R4, R6, R8, R9 = 1k Ohm resistors
  • D1-D4 = Schottky diode (Eg 1N5819)
  • C1-C4 = 100nF capacitors rated for at least 6V
  • Q1-Q4 = TO220 nChannel MOSFETs (Eg STP62NS04Z). Other appropriate MOSFETs will work and maybe substituted but these should have clamping >30V and some protection built in.
  • U1 = Opto-isolator (Eg CNY17-3). May or may not be needed depending on the type of crank sensor you are using. If your sensor outputs 0-5V directly, this can be left out and the sensor connected directly to digital pin 2 on the arduino

Dev Notes

The V0.1 board has several drawbacks and issues that are to be addressed for the next version. These include:

  • Lack of ground screw terminals. The board only has a single ground screw connector which must be shared by all sensors. This is less than ideal both physically and electrically.
  • The use of an opto-isolator for the crank sensor is of debatable value. Most suitable hall sensors will output 0-5V signals and I'm not sure it's worth the extra cost/space to support 0-12V+ sensors as well. This leads to the next issue:
  • No support for VR crank sensors. The next version of the board will either use a built in VR conditioner or will allow something such as [the jbperf VR conditioner board](http://jbperf.com/dual_VR/v2_1.html) to be plugged in if required
  • No bias resistors onboard for the 2 temperature inputs (CLT and IAT). In order to standardise the voltage divider circuit, these should both have a 2490 Ohm resistor
  • There is no fly back diode on the MOSFETs. Assumption for this board was that protected drivers would always be used, but the provision for a diode should be added for flexiblity.