Click on our menu buttons immediately below to find MegaSquirt® information quickly:
MicroSquirt® Module
V1/V2 MicroSquirt®
Important Safety Information
MicroSquirt® Support Forum
- MShift™ TCU
- MShift™ Intro
- GPIO Build Guide for 4L60E
- Base circuits
- GPO1, GPO2, GPO3,
GPO4 (gear LEDs)
- VB1, VB2, VB3, VB4
- PWM1, PWM2, PWM3, PWM4
- GPI1, GPI2, GPI5
(2/4WD, Input2, downshift)
- GPI3 (Temperature)
- GPI4 (Brake sense)
- EGT1, EGT2, EGT3,
EGT4 (non-CAN Load, line pressure, Input3, Input1)
- VR1 (Vehicle
Speed Sensor)
- VR2 (Upshift button)
- Finishing Touches
- Testing your
GPIO Board
- External Wiring Guide for 4L60E
- Current Release Code
- User Settings
- βeta Code
- Code Archives
- Purchase a
GPIO kit
- Working with the Shift Table
- Serial
Connection Troubleshooting
- CANbus
Set-Up
- Solving VSS
Issues
- Ports, pins, circuits, connections
- MShift™ Discussion
Forums
- Misc. MShift™
Topics
- MShift™ sitemap
- Template Project Code
- GPIO Board Intro
- MShift™/GPIO
Support Forum
|
Click here for MegaSquirt® MegaManual™ Information, Guides, and Links
MegaShift™ 7-Segment Gear Display
MegaShift™ v2.004+ code allows the user to set the state of the four gear indicator LEDs. Instead of using these outputs to drive discrete LEDs, you can use them to drive a 7-segment LED (or LCD) to display the current gear numerically.
To do this, you will need to construct a circuit using a 7-segment LED, a driver IC, and several resistors (on a proto board or something similar). Examples of such components are:
- 7-Segment LED: Digi-Key 160-1576-5-ND, $0.88 each.
- 4511 driver chip: Digi-Key 568-3124-5-ND, $0.61 each.
This is how these components should be connected:
The R1 to R7 resistors must be chosen to limit the current to 10 milliamps (the maximum for the 4511 chip). ~2.1 Volts are dropped in the LED itself.
- With a 5 Volt supply, the resistors should be at least (5.0-2.1)/0.010 = 290 Ω
- With a 12 Volts (nominal) supply, the resistors should be at least (14.5-2.1)/0.010 = 1240 Ω
1/8 Watt resistors are fine, but ¼W won't hurt either.
Note that the LED circuits on the GPIO board provide a ground for the LEDs. As a result, the circuits are grounded when "on", and 'floating' when "off". To provide a signal to the 4511 chip, these inputs must pull-up circuits. This is done by connecting each input to the supply voltage through a 1.0 KΩ resistor (R8 to R11 in the diagram). 1/8 Watt resistors are fine, but ¼W are good too.
Note that when connected like this with a pull up:
"on" in the tuning software is "low" at the 4511 input pin (i.e. the pull-up voltage is pulled low by the GPIO's conducting transistor), and
"off" is "high" at the input pin.
So for example, first would be set as:
- LED1 = "off" - LED1 circuit is not conducting, so it is pulled high through the supply voltage via R8; and thus 4511 pin D0 (pin #7) is high,
- LED2 = "on" - LED2 circuit is conducting, so it is pulling the voltage low; and thus 4511 pin D1 (pin #2) is low,
- LED3 = "on" - LED3 circuit is conducting, so it is pulling the voltage low; and thus 4511 pin D2 (pin #3) is low,
- LED4 = "on" - LED4 circuit is conducting, so it is pulling the voltage low; and thus 4511 pin D3 (pin #6) is low.
Then you configure the remaining LED outputs to give the appropriate number in each gear:
Value Displayed | D1 | D2 | D3 | D4 |
0 | "on" | "on" | "on" | "on" |
1 | "off" | "on" | "on" | "on" |
2 | "on" | "off" | "on" | "on" |
3 | "off" | "off" | "on" | "on" |
4 | "on" | "on" | "off" | "on" |
5 | "off" | "on" | "off" | "on" |
6 | "on" | "off" | "off" | "on" |
7 | "off" | "off" | "off" | "on" |
8 | "on" | "on" | "on" | "off" |
9 | "off" | "on" | "on" | "off" |
blank | "off" | "on" | "off" | "on" |
Click on the component links to the respective datasheets above for a complete explanation.
For neutral or park, 0 is an obvious choice. For reverse gear, you can use any number not already used for a gear, or you could blank the display. The display can be user-set to flash in reverse (you set two patterns - one can be blank - and the LEDs will alternate between them once per second).
Note the the decimal point ("DP" - pin #4 of the 7-segment display) is not connected. You could use one of the spare ports to signal some function using that LED, or you could tie it into the TCC output (with a resistor) to signal the TCC status.
MegaSquirt®, MicroSquirt® and MegaShift™ 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.
© 2010 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.