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PostPosted: Tue Feb 05, 2013 10:34 pm 
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http://ww1.microchip.com/downloads/en/D ... er_1.0.pdf

:shock: Some of those slides look familiar :shock:


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PostPosted: Tue Feb 05, 2013 11:58 pm 
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None of the through hole pic's I've found support both can and US, so it will make USB stick hard to do. Hopefully I've got a link to PC via USB sorted, but I will make sure I've got that sussed on the ECU before I commit PCB to manufacture on this.

SD card hardware looks easy to implement with the SPI interface built into the processor. Really not sure if it's worth the effort of sorting out the software side of it to handle the filesystems used by PC's on it. I may just put the hardware on the PCB and not bother fitting it unless it becomes desirable at a later date.

http://en.wikipedia.org/wiki/Secure_Digital

https://www.sdcard.org/downloads/pls/si ... 100518.pdf

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PostPosted: Wed Feb 06, 2013 12:16 am 
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I'll reply more fully later but I think SD is a good idea.

The technology is ubiquitous, large cards are very cheap, in terms of data logging at the circuit this means you can run two cards, just swap them over when the car comes back to the pits and there is minimal downtime.

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PostPosted: Wed Feb 06, 2013 12:44 am 
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For sure make the provision in hardware

If it comes to it you can probably keep the card internal only and just write a raw format to it. Then read back via USB
I totally forgot your USB interface was non native :oops:
Not as nice as swappable media but still gives you some benefit


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PostPosted: Wed Feb 06, 2013 4:20 pm 
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I blinked :lol:

Should be with me in time for dinner tomorrow


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PostPosted: Wed Feb 06, 2013 6:26 pm 
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Here's my thoughts on parameters to measure, from my research it would seem that most systems use Bosch type temperature (thermistor) sensors for oil, water and air temperatures. EGT's are a standard K type thermocouple and AFR is also via a Bosch wideband sensor.

There are a few options for pressure sensors - cheaper ones like the VDO are supported by many systems but these are quite bulky and unsightly. Many systems also seem to use a Bosch sensor although these are more expensive at around £80 each - possibly can be found cheaper.

The actual parameters - I am not sure whether they are digital or analogue?

These are the ones I see as really important:

Oil Pressure
Oil Temperature
Water Temperature
Boost
EGT
Fuel Pressure
Air Intake Temperature
Air Fuel Ratio

Less important but might be nice to have:

Chargecooler Coolant Temperature
Gearbox Oil Temperature
Rear Differential Oil Temperature
Power Steering Fluid Temperature

Now of course then you have the basic stuff like Fuel Quantity, Speed, RPM etc although those are not so important to me as I am keeping my dashboard.

I think an important factor with the sensors is the ability to use a different sensor if you choose - ie the ability to put in a custom calibration. :)

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PostPosted: Wed Feb 06, 2013 6:59 pm 
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First shot at the main box, just been reminded I haven't added a type K thermocouple amplifier yet (Useful enough to dedicate a channel I think). Also remembered I haven't added an audio warning.
So, one of the general purpose 0-5V channels below will become EGT with a typeK thermocouple amplifier.

https://dl.dropbox.com/u/8316230/dash/DigiDashA.pdf

The spec is:

Display 2 line of 16 character alphanumeric (Can arrange a bargraph or 2 on one line) Contrast & backlight adjustable via software. http://uk.rs-online.com/web/p/lcd-monoc ... s/5326379/
SD card (if fitted) - Since these must be 3.3V I added an extra cheap processor to interface to I2C
Built in eeprom logging memory (doesn't get lost if power fails) (alternative to SD)
4x buttons integrated with front panel membrane. Up/down & enter/back.
Box, near single din stereo (same height, 20mm narrower). May also be available in smaller din case but not sure yet.
USB connection to PC.
CANBUS connection for steering display & expansion I/O units (see viewtopic.php?f=13&t=6277 ) This should also be capable of providing OBD2 to allow use of android / torque or alternatively reading a modern ECU directly without the need to wire all the sensors.

Inputs:
Built in 3 axis G sensor.
Built in battery voltage measurement.
'Breakout loom' connector for vehicle specific loom to standard functions:
    SPEED. (5V pulse)
    RPM (5V pulse)
    FUEL (0-12V analogue)
    TEMP (0-5V analogue) - will read ECU sensor, ECU has pullup resistor already
    TEMP2 (0-5V analogue) - will read ECU sensor, ECU has pullup resistor already
    TEMP3 (0-5V analogue) - will read ECU sensor, ECU has pullup resistor already
    BOOST (0-5V analogue) - will read ECU sensor
Expansion connector
    5xGeneral purpose 0-5V, can be linked with individual pullup for temperature or resistance measurement.
    2xGeneral purpose 0-12V, can be linked with individual pullup for temperature or resistance measurement.
    Duplication for speed input (5V pulse)
    Duplication for fuel input (0-12V)
    Duplication for TEMP3
    Duplication for BOOST
    4xPullup resistors which can be linked to read resistance or thermistors directly on the 'breakout loom' sensors.
    +12V out (protected)
    +5V out
So a total of 12 analogue inputs, 3 of which are 0-12V, remainder 0-5V. Configurable to read resistance or thermistors.
A total of 2x Digital inputs.

Software wise, every input will be configurable with name & unit text, scaling values (possibly look up table format). 2 levels of alarm low & high and which level alarm each triggers (low = show on display, med = flash display, sound alarm, high = relay operation)

Selling price for this module looks like it will be somewhere £150 - £250, excluding looms & sensors depending on spec. (+VAT)

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Last edited by Nibbles on Sat Jun 15, 2013 1:56 pm, edited 3 times in total.

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PostPosted: Wed Feb 06, 2013 7:23 pm 
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Thanks Mike,

A quick google reveals some useful data.

https://dl.dropbox.com/u/8316230/dash/vdo_sensors.xls
http://www.vdo.com/generator/www/com/en ... ab=4629602

http://www.bosch.com.au/content/languag ... rature.pdf

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PostPosted: Wed Feb 06, 2013 10:29 pm 
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Yes also if you look at he Bosch Motorsport website there are datasheets for a host of sensors, most are way too expensive for our application but some are reasonably priced.

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PostPosted: Wed Feb 06, 2013 11:32 pm 
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Chris, if this comes together it should be really good. Watching progress with great interest :D

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PostPosted: Thu Feb 07, 2013 5:47 pm 
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Would 1023 deg C be enough for EGT ?

http://uk.rs-online.com/web/p/temperatu ... s/6987118/

Would save losing an existing channel.

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PostPosted: Thu Feb 07, 2013 6:09 pm 
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Hmm, I certainly think EGT's can go higher but as far as I know anything over 1k deg c is bad news lots of k type thermocouples read to 1100 deg.

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PostPosted: Thu Feb 07, 2013 6:13 pm 
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Also - here's that link for Bosch Sensors:

http://www.bosch-motorsport.de/content/language2/html/2589.htm

lots of interesting information there.

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PostPosted: Thu Feb 07, 2013 6:34 pm 
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That chip is also SPI rather than I2C so would need more pins. Shame.

Alternative: http://uk.rs-online.com/web/p/instrumen ... s/7590080/

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PostPosted: Sat Feb 09, 2013 6:20 pm 
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Just for you Chris. Schematic of the little 'scope

http://www.elechouse.com/elechouse/imag ... DS0201.pdf


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