DFH - Defacto FreeEMS Hardware in KICAD

[jharvey]

I still don't know how or where to post the schematic files, so I'll post a couple pictures instead. These pics are larger then can be viewed on a normal resolution, so I'm posting links that you have to click on.

The top page is here http://i324.photobucket.com/albums/k352 ... MS_pg1.gif
The power reg is here http://i324.photobucket.com/albums/k352 ... S_pg30.gif
The injector supply is here http://i324.photobucket.com/albums/k352 ... S_pg21.gif
The ADC filter is here http://i324.photobucket.com/albums/k352 ... MS_pg7.gif

The other pages aren't worth posting anything about yet. They only contain a couple links to the master page.

Normal flow in KICAD is to right click the box and select "enter sheet" The above links are some of the sheets you can enter.

[Fred]

Good work!

I think the ADC input one needs to be changed a little though, the resistance should be split, 1k to protect the CPU and Xk on the outside of the cap to form a first order low pass filter. The cap and resistor values can be user chosen/recommended at a later date for the specific input being discussed.

For the MAP input, the sensor data sheets show how they recommend interfacing it with a CPU and power supply :



BTW, have you seen this site : http://burnallgifs.org/ ;-)

I think you should put a spot for one SMD MAP sensor of part number MPX4100A for atmospheric pressure correction. Make this default for everyone so there is no question as to whether to use it or not ;-) (still disable-able in software though)

I think we will need a second Vreg for sensor duty too, the filtering doesn't have to be as extreme for that though.

Keep it up :-)

Fred.

[Brian]

Fred, do you have more sensors in mind other than temp/MAP/TPS sensors? 2 x temp sensors, 2 x MAP sensors and a TPS should draw less than 50mA. Hall sensors, LM1815's and opamps don't draw much either. 500mA would not be pushing an LM2940T if that's the one you are thinking of using. Processor 350mA + basic sensors 50mA, still quite a bit left, but definitely needs a good heatsink.

[Fred]

No, I don't off the top of my head, however those sensors if external to the board have the potential to cause a failure/overload and shut down the CPU unless you protect the outputs with something. For example, if your TPS goes short circuit on you you really want the rest of the ECU to keep on trucking. You are 100% right that it could be done with one, and I'm probably just being paranoid, thoughts?

[Brian]

The ecm power supply could be protected, but something else I never thought of is that any wire carrying 5V outside the ecm could also act as an antenna for induced noise? In the case of a TPS, the 5V is grounded through the pot itself, say 5K, so it may be a non-issue, or maybe not. Now, who's getting paranoid?

[jharvey]

I tried to attached rev A.01, but it gave me this error message.

"Sorry, the board attachment quota has been reached."

The file size is 41k, so it's not very big.

[Fred]

Fixed!

I had it set to 1 meg per whole board... I thought it was 1 meg per user... It's now 100 meg for the board with 1 used up, go for it! :-)

[jharvey]

Here is a partial release of the KICAD files for freeEMS. It includes the libraries so so it should work as is.

Some notes,

-- to get the symbols to work for me, I have to open freeEMS_1, then "enter sheet" from this page. If I don't it doesn't load the symbols for some reason.
-- to enter a sheet you right click in the blank area of a sheet, not on the text, or sheet border lines.
-- if the libraries don't work you can add them manually by using the library editor.

What's included in this release, sheet 1 is the top drawing of the hiearchy from there you enter other sheets. Included sheets are the MAP sensor input, Vreg, analog protection and injector driver.

[jharvey]

Here's A.02, includes many more top level interconnects, draft schematics for TPS, Vbat, MAP, RPM and thermistor input, also includes injector drivers and 5Vreg.

Missing details in top schematic interconnects, CPU schematic and ignition drivers.

[jharvey]

Not really a lot of changes this time, mostly I figured out how to get the PDF's to work, so here it goes w/ pdf's. I added the VR to the RPM input schematic.

To create these PDF's I plotted to post script, then ran ps2pdf to get them into pdf format. A script that converts all *.ps files would be nice so I don't have to type them.