Click on our menu buttons immediately below to find MegaSquirt® information quickly:

Click here for MegaSquirt® MegaManual™ Information, Guides, and Links

MegaShift™ Voltage Manual Lever

The MShift™ code allows for a variable voltage manual lever, rather than discrete inputs that are grounded to activate. This is the OEM setup for many ford vehicles, among others. The lever signal is fed to processor pin PAD00 (typically through EGT4/Ampseal pin 26 - circuit modifications may be needed, see 'creating a voltage measuring circuit' here:

Rs forms a voltage divider with the currently connected resistor (Rp, Rn, Rr, R4, R3, ...). If the resistance for a particular gear is Rx, the resulting voltage signal to MShift is:

Vx = (Vs × Rx) / (Rs + Rx)

Note that the values for the individual shift resistances (Rp, Rn, Rr, R4, R3, ...) should be different. That's what creates a unique voltage signal in each gear.

Here is a calculator to assist in calculating the resulting voltages:

Voltage, supply (Vs): Volts
Resistance, Rs Ohms
Resistance, Rx Ohms
Signal Voltage Volts

The 5Vref from your MShift™ controller (Ampseal pin 28) is a much more stable voltage supply than the 12.6 to 14.5V of the vehicle's nominal "12V" supply, which can help reduce the required tolerances.

You should measure the actual signal voltage for input to your MShift™ controller, but the above calculator can help you choose the resistors and see the effects of changing supply voltage (to assist in setting the voltage tolerances). Keep in mind that resistors typically have a tolerance of 10%, sometimes more. The voltage seen by the controller are in the ADC output channel as In1adc (0=0 Volts, 1024 = 5.0 Volts; divide the ADC count by 204.8 to get the Volts).

MegaSquirt® and MicroSquirt® controllers are experimental devices intended for educational purposes.
MegaSquirt® and MicroSquirt® controllers are not for sale or use on pollution controlled vehicles. Check the laws that apply in your locality to determine if using a MegaSquirt® or MicroSquirt® controller is legal for your application.
© 2012 Bruce Bowling and Al Grippo. All rights reserved. MegaSquirt® and MicroSquirt® are registered trademarks. This document is solely for the support of MegaSquirt® boards from Bowling and Grippo.