DSATX Shutdown Sequence???

**nm3th** · 02-10-2006, 10:16 PM

I'm planning my wiring scheme for my setup and a couple of questions came up.

When does the DSATX send the pulse to shutdown the mobo? Does it send the pulse as soon as the ACC line goes low or after the delay determined by P1? I'm not sure if P1 refers to the delay in sending out the pulse or the amount of time you have until the unit itself powers down.

Also, what happens if the ACC line goes low momentarily and comes back up to +12V? Does the unit start the shutdown process?

Thanks.

**DarquePervert** · 02-11-2006, 07:03 AM

P1 determines the amount of time before initiating shutdown. Read the specs here: http://www.mpegbox.com/dsatx.html

Why are you worried about your ACC line going low? If it does, you've got a more significant electrical issue in your ride and need to resolve that before putting any high-ened electronics inside...

**SMOKINV8** · 02-11-2006, 10:53 AM

By acc line going low, I think he's referring to turning off the key (v=0).

**nm3th** · 02-11-2006, 01:47 PM

I'm trying to figure out how I should wire it up. From my previous post, when I said ACC line, I was refering to the car's ignition.

My goals are:

1) Normal operation- DSATX turn on PC when ACC goes high
2) Manual operation- Trigger DSATX to turn on PC with car off (ACC low)
3) Valet off- prevent operation of DSATX
4) "Gas Mode"- When I'm getting gas, I don't want the DSATX/PC to shutdown when I turn off the car. Basically I want to go from Normal operation to Manual operation and then back to Normal operation when I restart the car.

I haven't been able to find a make-before-break switch, otherwise I would not have to worry about the DSATX's ACC line seeing low voltage during the switching process of going from Normal operation to Manual operation and vice versa.

Or I might have to ditch "Gas Mode" if my battery drops below 10V while cranking. According to the specs, P2 determines the low voltage threshold and 10V is the minimum.

****EDIT****
I just measured the voltage during cranking and it drops to 10.4V

**DarquePervert** · 02-11-2006, 03:57 PM

zootjeff has come up with various wiring schemes for the DSATX here: http://www.mpegbox.com/microsdc/usdc20d_InputCS.pdf

There should be something there that will help you figure out what you want. I'm going to use either Sceme F so that I can manually power the PC on/off at will or be able to leave the system off completely, like a valet switch.

**zootjeff** · 02-12-2006, 02:12 AM

Do look at that diagram for the USDC.

The DSATX has a 10 second timer on the low voltage setting for cranking. Basically if you crank for less than 10 seconds, the voltage could drop down to 8 volts and still not hickup or trigger the low voltage setting. Bascially when the battery is getting low, it has to stay below the threshold for 10 seconds before it is actually a low voltage condition..

The ACC line has 1 second of hysteresis so you don't actually need a make before break switch. Any SPDT (Single pole Double Through) switch will work.

Make before break might acually be damaging to your car system because your ignition line will go high without the key actually doing it which could cause weird results..