Shutdown Controller?

**KyleYankan** · 07-26-2005, 01:00 AM

Hi everyone. I'm about to commence the actual installing of my second carputer, just need to order a screen. However, there is one thing that's been on my mind, and I posted about a few times before. A shutdown controller. Basically, I'm not looking forward to spending any cash. I'm very hampered in my budget, and the screen is going to cost me well over my remaining budget, and tap into schooling funds a bit. So, any money saved is good money. Now, I used a basic form of a shutdown controller on my older, ghettoer carputer. Worked fine, till I forgot about the diode across the relay and fried my motherboard.

However, I want to go with a more external solution this time. I wanted to use a PIC microcontroller. I have a programmer, and alot of the support elefctronics needed already (max232, darlington pairs, a few varietes of pics, and a few 4mhz ceramic resonators). Well, It's time to build again.

I wanted a Shutdown controller that can ignore any ACC switching less than oh, say 5 seconds. Help when cranking, to keep the PC from shutting down. My next thing is a flick switch - then 45 secs later kill power. To prevent hanging. My final problem is hoping to avod the serial or parallel port. I can tap into the 5v, or 12v line, with a bit of case modding.

So, does anyone know of a Startup/shutdown controller that can do any of this? Mos tof the DIY's are based around a fake UPS, or something like that. not many people can program a PIC,and have all the other IC's to do it. Any help is appreciated. Thanks!

**Curiosity** · 07-26-2005, 10:41 AM

Well, I could offer some ideas. Scroll down to the HIDiouSDC project here and grab the source code: http://curioustech.home.insightbb.com/carpc.html

user.c has the SDC and other routines in it and hidsdc.h is the windows code. There's more to it for the OBD-II, relays, SWC, IR, radar detector and all that but you could rip all that out and just use the SDC part. In SDC_Sequencer() it checks ACC every 500ms, then if it's on, it checks again 500ms later before turning on the PC. There's also an instant on if a power button is pressed (or door unlock). The shutdown timer is set by software though.

**evandude** · 07-26-2005, 10:58 AM

if you're looking for a SDC that's a little less of an "everything in your car controller", then you can check out mine...

http://eegeek.net/mp3box/SDC/

although as a side note to Curiosity... I am quite interested in getting a PIC USB HID interface working at some point, so that device and your associated code is quite intriguing!

Check your PM's, I have a question or two for you.

**KyleYankan** · 07-26-2005, 10:33 PM

evandude: I'm assuming the timer switch is a momentary?

BTW, thanks for the circuit - that's a pretty sweet SDC. I like how youre planning on implementing analog inputs. Have you considered a voltage input? if voltage is below 11 volts, kill power?

**evandude** · 07-26-2005, 11:04 PM

yep, momentary. each time you push it toggles the delayed shutdown mode (as displayed by the LED)

yes, monitoring input voltage is one of the intended uses as well.

also, keep an eye out for new source code. the original code is pretty much all in the main function, and is a big mess of conditionals (got to love state machines) So i have separated it into separate functions for each state (computer on/off, ACC on/off) to make it a lot easier to follow, for anyone interested in toying with it. I haven't put it up yet though, as i haven't tried it out on the board yet.

One of my other immediate goals is a serial interface for changing settings. When I start implementing stuff like monitoring analog voltages, and wanting to be able to customize delay times without changing the source and recompiling and all that, there really needs to be a serial interface to change stuff in real time. It's not so much of a problem on the PIC side of the world, since I've done serial many dozens of times, the problem is on the computer side, after all, I'm a EE, not a programmer, so my ability to develop decent windows programs to use the serial port is rather limited... I've done it in VB before, it just takes me forever.

**Curiosity** · 07-26-2005, 11:19 PM

I've decided voltage isn't really as important as making sure the power is always cut off (after all those crazy comparater things). Unless you have a yellow top, draining the battery is hard on it, so having it on for hours without charging from the alternater shouldn't even be thought of. Just go with evandude's SDC. It's a nice, solid design.

**KyleYankan** · 07-26-2005, 11:45 PM

heh. evandude: look for a bootloader if you want to be able to play with stuff on the serial port. It'll let you reporgram a pic in a flash. But, that's probably not what you want. anyways, have fun. Keep me updated! Thanks!