Search found 21 matches

by erich
Fri Dec 27, 2013 8:01 am
Forum: Hardware
Topic: Interfacing with a LCD/tablet dash
Replies: 14
Views: 2851

Re: Interfacing with a LCD/tablet dash

The Discovery board it totally is fast enough to run an LCD display. I run one of these in my car: http://www.ebay.com/itm/new-7inch-7-0-800-480-TFT-LCD-Module-Display-Touch-Panel-SSD1963-For-51-AVR-/111140237971?pt=LH_DefaultDomain_0&hash=item19e0797293 The discovery board runs datalogging for the ...
by erich
Fri Nov 15, 2013 7:55 pm
Forum: Hardware
Topic: VR + knock module
Replies: 37
Views: 11245

Re: [help needed] VR + knock module

russian wrote: You are not alone, I've got six Russians fighting about it at http://rusefi.com/forum/viewtopic.php?f=8&t=251 :)
It's all greek to me.
by erich
Thu Nov 14, 2013 8:11 pm
Forum: Hardware
Topic: VR + knock module
Replies: 37
Views: 11245

Re: [help needed] VR + knock module

It's easy enough to bodge together a fixed function bandpass filter in code. Here is a good source: http://www-users.cs.york.ac.uk/~fisher/mkfilter/
Acoustic knock detection is still a weak way to go. Ion sensing is much better.
http://vvnet.fi/ville/ion/DIY-Ion-Sensing-2.pdf
by erich
Thu Nov 14, 2013 8:01 pm
Forum: Hardware
Topic: 6 channel injector module - VNS14NV04
Replies: 22
Views: 14803

Re: 6 channel injector module

I like those switches, but man are they slow.
The speed isn't an issue for injectors but with a switching time that long they're going to dissipate quite a bit more heat.
I probably would have gone with the DPAK for better dissipation.
by erich
Fri Nov 08, 2013 6:20 pm
Forum: Hardware
Topic: Thermocouple input?
Replies: 54
Views: 13080

Re: Thermocouple input?

The MAX31855 is about the simplest way to do a thermocouple input. It handles the cold junction compensation, linearization and A/D conversion. A simple bit banged interface and you're all set. It's even cheap. If I had known it existed befoe today I probably would have put one on my digital dashboa...
by erich
Sun Nov 03, 2013 8:31 pm
Forum: Software
Topic: A different approach.
Replies: 46
Views: 11168

Re: A different approach.

Cars used to run open loop at WOT but they don't any more. Most modern ECUs use a WBO2 because WOT is a tested parameter for the EPA and they can't get away without it. That's why you can get a Bosch WBO2 sensor for cheap now. I'd use a separate table for the correction so you can wipe it without wo...
by erich
Fri Nov 01, 2013 3:16 am
Forum: Hardware
Topic: What about fancy output drivers?
Replies: 12
Views: 2936

Re: What about fancy output drivers?

Not enough drive current.
A saturated injector takes about an amp to drive. I peak/hold injector uses about 4A for a milisecond or so then 1A hold.
That driver can only do 625ma per driver.
by erich
Thu Oct 31, 2013 7:46 pm
Forum: Hardware
Topic: Variable Reluctance input
Replies: 15
Views: 3986

Re: Variable Reluctance input

The Maxim IC is fancy, and only available in fine pitch surface mount. It'll be a total bear to solder by hand. The ON chip is simpler and a dual VR amp, with .050 lead spacing which is easily doable by hand. The big difference between the TI chap and the ON chip are the outputs. The TI chip outputs...
by erich
Thu Oct 31, 2013 7:26 pm
Forum: Software
Topic: A different approach.
Replies: 46
Views: 11168

Re: A different approach.

If you want to keep it as simple as possible how about this: A simple alpha N table to get it close (+-5% or so) A WB O2 sensor. A second table with a multiplier based on a single target AFR from the WB O2 that's the same size as the main alpha N table. A clamped feedback loop that ticks fuel correc...
by erich
Fri Oct 25, 2013 6:00 pm
Forum: Software
Topic: Fuel Pump control.
Replies: 10
Views: 2882

Re: Fuel Pump control.

I'd do it with more of a watchdog approach.
Turning on the ECU and getting crank signals reset the watchdog. If the watchdog expires, turn off the fuel pump.
by erich
Thu Oct 24, 2013 8:38 pm
Forum: Software
Topic: Fuel Pump control.
Replies: 10
Views: 2882

Re: Fuel Pump control.

It's important to turn off the fuel pump ater a couple of seconds of no crank angle changes.
You do not want the fuel pump running for more than a few seconds if the engine stalls for safety.
Think fuel line ruptures.
by erich
Sat Oct 19, 2013 7:15 pm
Forum: Hardware
Topic: Power supply - Sergey89
Replies: 20
Views: 6906

Re: Power supply - Sergey89

That's why I used a 3.3v rated voltage transorb http://www.semtech.com/apps/product.php?pn=SRDA3.3-4 I'm not worried at all about ripple. There's alread a LDO on the discovery board that the analog stuff references. I also added 470uf caps on the 12v, 5v, and my own 3.3v LDO that I use for pull-ups.
by erich
Fri Oct 18, 2013 8:42 pm
Forum: Hardware
Topic: Injectors driver - Sergey89
Replies: 4
Views: 2021

Re: Injectors driver - Sergey89

National used to have 4 channel peak/hold injector drivers but I don't see them on the TI website.
They still have the LM1949 but it's kind of bulky. They have lots of high current automotive drivers as well.
by erich
Fri Oct 18, 2013 8:34 pm
Forum: Hardware
Topic: analog inputs: op-amp + divider - Russian - now MCP6004
Replies: 126
Views: 36628

Re: analog inputs: op-amp + divider

Sergey89 wrote:TVS and Zener diodes has a large leakage current. Low leakage diode is more preferred device (BAV199 for example).
if 15pf and <1ua leakage is too much input loading, you're not reading automotive sensors.
by erich
Fri Oct 18, 2013 8:28 pm
Forum: Hardware
Topic: Analog inputs - Sergey89
Replies: 6
Views: 2102

Re: Analog inputs - Sergey89

R5 - C5 are a nice RC input filter, takes out a lot of hash.
Ditch the opamp and clamp diodes, use a resistor divider and a transorb. I used these http://www.semtech.com/images/datasheet/srda3.3-4.pdf for my i/o protection.
by erich
Fri Oct 18, 2013 8:26 pm
Forum: Hardware
Topic: Triggers - Sergey89
Replies: 2
Views: 1257

Re: Triggers - Sergey89

That's a lot of circuitry to replace one of these: http://www.semtech.com/images/datasheet/srda3.3-4.pdf
by erich
Fri Oct 18, 2013 8:23 pm
Forum: Hardware
Topic: Actuators driver - Sergey89
Replies: 3
Views: 1164

Re: Actuators driver - Sergey89

How much current do you need to sink?
I used TLE6225G low side drivers with fault protection. Why re-invent the wheel on something this boring?
by erich
Fri Oct 18, 2013 8:21 pm
Forum: Hardware
Topic: Power supply - Sergey89
Replies: 20
Views: 6906

Re: Power supply - Sergey89

I used these:
http://www.ebay.com/itm/10PCS-DC-DC-LM2 ... 58a1563404

All of my I/O are clamped with transorbs, no worry about dumping into the power supply.
by erich
Mon Oct 14, 2013 7:33 am
Forum: Hardware
Topic: analog inputs: op-amp + divider - Russian - now MCP6004
Replies: 126
Views: 36628

Re: analog inputs: op-amp + divider

Keep the input protection. It's much better to blow out an external diode then the a/d inputs. I use a TVS diodes, in a quad unipolar 3.3v package for protection. I also don't bother with the buffer opamp. I have a 'universal' input with an input resistor, a pull up and down and a cap to ground, fol...
by erich
Wed Sep 04, 2013 5:55 pm
Forum: Software
Topic: output scheduling resolution
Replies: 20
Views: 14370

Re: output scheduling resolution

If you can keep jitter under 2us when doing the processing you need to do then you're golden.
by erich
Tue Sep 03, 2013 5:11 am
Forum: Software
Topic: output scheduling resolution
Replies: 20
Views: 14370

Re: output scheduling resolution

The real test will be to make about a dozen timers all running with slightly different periods at the same time and check the jitter then. Also make each handler burn a hundered clock cycles or so to get a more realistic load. Assuming you want to be able to control an eight cylinder engine you need...