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MegaShift™ Hardware

The MegaShift™ code uses the Bowling and Grippo GPIO hardware that communicates with a MegaSquirt-II™ CAN enabled engine controller to get the engine rpm and load (MAP kPa).

Here are the MegaShift™ Port Assignments:

Transmission
Function
Processor
Port
GPIO
Circuit
GPIO AMP
Connector Pin
Output1 (Sol A)PE4VB323
Output2 (Sol B)PM2VB435
Output3 (Sol32)PT1PWM434
PCPT2PWM333
TCCPT3PWM232
LED1PM4GPO110
LED2PM3GPO27
LED3PM5GPO38
LED4PB4GPO4 9
Input 1 (switchA)AD0EGT4 (build as GPI)126
Input 2 (switchB)AD1GPI2 (jumper at 25x2 header)6
Input 3 (switchC)AD3EGT325
Mode switchPT5VR3 14
Paddle UPPT6VR2 15
Paddle DOWNAD6GPI54
VSS PT0VR12
Temp SensorAD2GPI330
Brake SenseAD7GPI43
Speedo OutputPT4PWM131
Spare Output1 (SP1)PT7VB1
(jumper at 25x2 header)		11
Spare Output2 (SP1)/Output4PA0VB212
non-CAN MAP/TPS/MAFAD5EGT124
Line Pressure SensorAD4EGT227
2WD/4WD Sense/Input4PE1GPI15

1 Build EGT4 as voltage input circuit: install R70 (1KΩ), JP9, substitute 5.6 volt Zener diode in C44 (banded end towards copyright notice); C43 for noise control if necessary.

The GPIO main board must be built to the above specifications (more details will be added here shortly).

Example Application: 4L60E Shift Logic

The following table illustrates the hardware logic required to shift gears in the 4L60E. Note that the transmission can be electronically shifted between the 4 forward gears, neutral, park, and reverse must be selected with the shift lever (though the shift lever position can be detected via the switch manifold feedback). Once in Drive, the transmission's forward gears can be controlled.

A nice design feature of the 4L60E is that shifting the transmission electronically does not require any precisely coordinated events, so timing is not crucial. Shifting from one gear to the next is always accomplished by turning on or off a single solenoid. In fact, the most precision used is to determine the output shaft rpm, which is not at all critical in this application.

The following table gives the state of transmission's inputs and outputs for each gear, as well as what needs to change during upshifts and downshifts.

GearSOL ASOL B3/2 SOLPCLED1LED2LED3LED4
ReverseononoffPWM% based on loadflashflashflashflash
Neutral/Parkononoffoffoffoffoff
1ononoffPWM% based on loadonoffoffoff
1/2 upshiftswitch offonsw 90%PWMPWM% based on loadswitches onsw on offoff
2/1 downshiftswitch ononsw offPWM% based on loadonsw offoffoff
2offon90% PWMPWM% based on loadononoffoff
2/3 upshiftoff switch off90% PWMPWM% based on loadononsw onoff
3/2 downshiftoff switch onPWM reducedPWM% based on loadononsw offoff
3offoff 90% PWMPWM% based on loadon ononoff
3/4 upshiftswitch onoff90% PWMPWM% based on loadonononsw on
4/3 downshiftswitch offoff90% PWMPWM% based on loadonononsw off
4onoff 90% PWMPWM% based on loadonononon

Note that SWA, SWB, and SWC indicate the position of the manual valve (the shift lever, in essence). This tells MegaShift when the transmission is in park/neutral, reverse, D1, D2, D3, or D4. The values for the switch manifold shown above indicate manual valve position, NOT the currently selected gear. The switch manifold information is used to limit upshifts, where desired. Note that engine braking (via the overrun clutch in the transmission) is only available when the manual valve is in position D3, D2, D1.

Steady State Monitoring Configuration

Reverse

Neutral/Park

First

Second

Third

Fourth

Shift 'Mechanism'

The basic shift control strategy (how to shift, as opposed to the determination of when to shift) looks like this:

* Upshifts *

First-Second

Second-Third

Third-Fourth

* Downshifts *

Fourth-Third

Third-Second

Second-First

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.
© 2004, 2009 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.