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FreeStim idea 
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LQFP144 - On Top Of The Game
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Joined: Thu Feb 25, 2010 3:57 am
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Location: Gosport, IN USA
Ok, so I have given this some thought and figured I should share my idea for everyone's benefit and assistance with the development of a FOSS stimulator for DIY ECUs.
My references below are based on the Jaguar schematics.

    So here is my idea for "FreeStim":
  • Use an MC9S12XDP512 112-pin MCU on a removable development board (so it can be used for other things as well) that would plug into the "FreeStim" board. This will allow us to use the FreeEMS benchtest (DEFAULT) firmware along with software like https://github.com/johnhowe/Lacerated-Pempheridae to simulate the RPM0 and RPM1 input patterns via the Port T0 and T1 outputs from the development board.
  • Use a TC4427A that would be connected to the T0 and T1outputs from the development board MCU to allow the selection of a 5v or 12 pull up of these inputs to simulate OEM trigger sensors (RPM0 and RPM1 inputs on the ECU).
  • Use potentiometers for CHT, IAT, MAF, O2, SPR1 and TPS.
  • Have LEDs for High Power LSD outputs (Injectors) 1-8, Medium Power LSD outputs (Fuel Pump, LSD1 and LSD2), 5v (Analog-5v/TPS-5v) output and PWM idle valve output.
  • Have a toggle switch on the +12-16vdc (battery connection) input to the onboard regulator.
  • Have an onboard LM2940T +5v low dropout regulator with a 0.5A thermal fuse and a power on LED.
  • Have an onboard LM7812 +12v regulator to test the BRV input on the ECU with a known value.
  • Have 0.100" header strips for +5v, +12v, +12-16v (battery connection) and GND.
  • Have a Molex "Mini-Fit, Jr" style connector so that adapters can be easily made by the user to adapt to whatever connector(s) they are using for their FreeEMS or other ECU.

I welcome any feedback regarding this idea.

Andy.

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Andy.
FreeEMS vehicle #11, 1932 Ford 5 Window Coupe with a 1996 GM 3.1L SFI V6 with DIS ignition
FreeEMS vehicle #16, 1996 Chevrolet S10 2.2L SFI I4 with DIS ignition
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Sun Sep 01, 2013 7:07 pm
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Quote:
Use an MC9S12XDP512 112-pin MCU on a removable development board (so it can be used for other things as well) that would plug into the "FreeStim" board. This will allow us to use the FreeEMS benchtest (DEFAULT) firmware along with software like https://github.com/johnhowe/Lacerated-Pempheridae to simulate the RPM0 and RPM1 input patterns via the Port T0 and T1 outputs from the development board.

Smart idea. How about 4 outputs, though. Think modern V/flat engines with dual VVT, etc.

Although I intend to continue dev of the BenchTest firmware, it's worth noting that a dedicated CPU could be developed for more cheaply. However, I like your idea a lot. Good thinking!

Quote:
Use a TC4427A that would be connected to the T0 and T1outputs from the development board MCU to allow the selection of a 5v or 12 pull up of these inputs to simulate OEM trigger sensors (RPM0 and RPM1 inputs on the ECU).

Along these lines, how about matching each +ve signal with an inverted friend? Then you could feed a max input without any messing around/bypassing.

Quote:
Use potentiometers for CHT, IAT, MAF, O2, SPR1 and TPS.

Supply more, 10 or 12, or 15, or 20, and don't label them, instead leave 5x20mm white silkscreen rectangle to write on with a fine tip marker. Max out an order option, so 10x10 or 10x20 and fill one whole side with pots. However.... dreaming a bit, if we could access the 8 PWM ports of the dev board, then we could buffer them through filters and op amps and have analogue outputs under sw control. Worth dreaming about IMO. You could even set gain to be higher and use raw 15v supply for various sensor styles. 3 terms each should be easy to re-route/configure as variable to-gnd, to-power, or variable volts. places for to-ppower and to-ground current limit resistors. I burnt a pot on my jimstim... for these resistors, a 1/4w flat footprint with solder blob bridge under it in case not needed.

Quote:
Have LEDs for High Power LSD outputs (Injectors) 1-8, Medium Power LSD outputs (Fuel Pump, LSD1 and LSD2), 5v (Analog-5v/TPS-5v) output and PWM idle valve output.

More the merrier, as with pots, put them in a line, and unlike pots, put the name strips side by side with the LED at the end of each name strip. I might try to mock up a board in kolourpaint. Multiple colours in BOM please. If we can fit 40, that'd be good. 36 = v12 COP staged inj = end goal.

Quote:
Have a toggle switch on the +12-16vdc (battery connection) input to the onboard regulator.

Bridgeable, but is it necessary at all? You shouldn't be leaving power supplies running anyway, turn it off at the wall?

Quote:
[*]Have an onboard LM2940T +5v low dropout regulator with a 0.5A thermal fuse and a power on LED.

To power the dev board? or? How about using ECU output 5V instead?

Quote:
Have an onboard LM7812 +12v regulator to test the BRV input on the ECU with a known value.

Can we safely assume a DMM? This requires a 14V+ input and seems like over-complicating it. Maybe make it optional? I guess we need a 14.4+ V supply anyway to feed the DUT.

Quote:
Have 0.100" header strips for +5v, +12v, +12-16v (battery connection) and GND.

Good, but keep them a bit apart to avoid accidental fryage.

Quote:
Have a Molex "Mini-Fit, Jr" style connector so that adapters can be easily made by the user to adapt to whatever connector(s) they are using for their FreeEMS or other ECU.

How about a 40 pin or pair of 40 pin headers, and have a board with sockets that adapts to the connector? or a small loom adaptor that has XYZ plug on one end and header sockets on the other? Seems like a waste of molex connector?

BRB, time to draw.

Fred.

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Mon Sep 02, 2013 1:24 am
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5 pixels per mm, 1000x500pixels vx 200x100mm

Image

Black strips on edge = ECU connector headers.

Other black strips = 5, 12, 14.4, and ground vertically.

Four strips of 12 LEDs in 4 colours.

12 big pots along the edge.

Fred.

_________________
DIYEFI.org - where Open Source means Open Source, and Free means Freedom
FreeEMS.org - the open source engine management system
FreeEMS dev diary and its comments thread and my turbo truck!
n00bs, do NOT PM or email tech questions! Use the forum!
The ever growing list of FreeEMS success stories!


Mon Sep 02, 2013 1:53 am
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DIP8 - Involved

Joined: Fri Aug 16, 2013 6:59 am
Posts: 21
Instead of 12 pots. How about 6 pots and 6 digipot and/or DACs? Preferably with I2C interface, so you can have multiple on the same control bus.


Tue Sep 03, 2013 3:19 pm
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LQFP112 - Up with the play

Joined: Wed Aug 28, 2013 6:07 am
Posts: 145
I cobbled a megastim together for about 12 bucks IIRC. variable square wave RPM control, variable 02, CLT, IAT,TPS pots and visual RPM and 2 channel injector firing via LEDs. Add a bunch more variable 0-5V, 0-12V pots to taste. Modular!


Mon Dec 02, 2013 12:12 am
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