MPGuino release one workspace

[dcb]

Mine is 15V, 500ma. I think the LED backlight alone needs 200ma when on full.

[Yoshi]

Originally Posted by dcb

at some point during the long test, the trip mph dropped to 8.5mph instead of 20mph, probably overflowing, instant is fine.

I checked your numbers and program code.
In the mph() routine, there is one, (vssPulses*3600).

You saw 2,148,300 (vssPulses), then vssPulses*3600=7,733,880,000, which is 0x1CCF9A4C0 in hex. It becomes more than 32bit, or more than the unsigned long range.

Yoshi

[cmags]

Originally Posted by dcb

Mine is 15V, 500ma. I think the LED backlight alone needs 200ma when on full.

Yea, I just ordered new LCDs, because when I plugged in my laptop adapter (16V, 4.5A), it ran the blink test program just fine, but the second I plug in my LCD, the 7508 starts overheating and I have to pull the power within a second or so or things would definitely smoke. Must be a short on the LCD. I'll try to fix it later, but it wasn't backlit anyway so I've got these incoming:

http://cgi.ebay.com/ws/eBayISAPI.dll...m=160247143835

So after that, I should be OK on the hardware. I still need to find that VSS hookup, but I've found a few references to it in my car's wiring diagrams - just need to translate diagram to actual harness location.

I still need to know what information about my injectors I need to know to determine my custom constants in the code. I've read through and found references to specs such as open time and duty cycle and flow rate for the injectors, but I'm quite lost. Is there some newbie information on injectors for determining what I need to know to get this project moving?

[dcb]

FYI, no backlight on those too. I was just checking them out yesterday in fact. You can just point an LED at it I suppose and coat the back of the LED with black paint so it doesn't glare.

The other LCD caveat that paulb gave me was that the temperature range on some LCDs isn't very good. They just go blank below a certain temperature. The "official" one looks like it is 0 deg C ~ +50 deg C per the spec. We might want to reconsider that display before winter gets here. There are a bunch on mouser.com that claim -20 to +70 operating temp for not a lot of money.

[cmags]

Awww, crap. I saw the schematic on the page and it showed the LED+ and LED- so I thought it was backlit. Damn. Maybe I can get him to cancel the order.... thanks for the heads up though.

[dcb]

Sorry dude, the auction was definately misleading, you have a case. They put a schematic up there with LED +- on it.

[MilesPerTank]

I've got a nice 40x4 LCD that is LED back lit. I'm not even going to try to run it off a 7805 unless i can find something much lower than 12V as the input voltage.

I/we should hunt down a decent sized power resister and run it inline with the 7805 in all honesty.

[cmags]

Damn, this is what I got back from the seller:

Hi,

We tried to stop your shipment, unfortunately, the post master left with all of our shipments of the day and from the weekend. On any other day we may have been able to stop shipment, but on Mondays its very difficult to the volume of shipments accumulated from the weekend.

We are sorry that we could not stop the shipment.

O-well, maybe I'll try to get them to send me something discounted... but these will do as test pieces...

@MilesPerTank: I don't see why the 7805 wouldn't work out for your LCD... If you're worried, hook up a dedicated 7805 circuit for your LCD.

[dcb]

The current requirements for a 40x4 backlight are probably 5x that of the nkc LCD, which would put it at the limit of a 1 amp 7805 (and the 2n306 wouldn't handle the current either).

But anyone deviating from the "official" LCD does so at their own risk. Well, it's all at your own risk really but there's lots of variables in LCD land and I aint a sorting all that out for everyone. If you know what you are doing, then that's fine, but there's too much else that needs doing for me to hardly mess with it.

[dcb]

Originally Posted by Yoshi

It becomes more than 32bit, or more than the unsigned long range.

Thanks much for confirming the overflow. Any thoughts you'd be willing to share on the trip vs instant mpg discrepancy? Or better yet, a generic way to multiply and divide 32 bit numbers while not overflowing but retaining max resolution (without a bunch of "if" statements)?