OK, this is going to be very complicated-just bear with me! I'm a half good PIC microprocessor programmer, and i've got some ideas that i want to impliment with the aid of a PIC programmer. I know that when the PC is off, the only power is a 5V line going into the motherboard which allows for the push to make button to work. Brilliantly, the PIC microprocessor can run on a 5V line, so i can have the PICs powered up while the PC is off. Which is good, because i want certain functions to be avaliable when the PSU isn't active. Alright, time to dive right in...
PIC 1:
Pic 1 is going to control a door in the case, which opens up to reveal the fan speed controllers. All the case fans are going to be hooked into a single controller, with the CPU fan hooked up to the motherboard as usual. The case fans will be controlled by the buttons behind the door, but wll start up at medium speed. The Fans are going to be connected to the PIC, which is going to produce a voltage output with some sort of Analogue to Digital relay circuit, that is the fan speed is controlled by the PIC. The fans are going to have 10 speeds, and an LED matrix will display which speed the fans are currently going at. The Door will open on startup, and after shutdown, i want the door to close. I'm doubting the 5V will be enough to power the motor after shutdown, but anything's possible i guess. There's also going to be an emergency in port, in case the temp gets too high, turning all the case fans onto full blast. Pin count here is 5 pins for the LED matrix, 1 pin for the emergency in, probably 4 pins to control the door, and another pin which is high when the computer is powered up, and low when the computer is powered down. So i'll need 11 GPIO pins, which is ok-there are 13 GPIO pins on the 16 bit PIC.
PIC 2: Pic 2 is going to drive 2 temperature sensors. It's going to take a temperature signal from the CPU and from the case, and it's going to display in on two analogue counters on the front of the case. This means that on power down, the analogue counters get reset-so i want to have the analogue counters reset either on startup, or when the CPU powers down. As far as i know, the only way to do this is to reset it using the 5V line, when the PIC detects that there isn't any Power going to the motherboard, i.e. the PSU is powered down. This will require another 16bit PIC i think, as well as having an emergency out line to send to PIC1 should the temperature of the CPU or the case rise to an unacceptable level. If it continues to rise too far, then the PIC will send a power-down signal to the motherboard, which should only cut in when there's a major temp increase-this wouldn't really be necessary because the mobo probably shuts down at a certain temp, but all the same, what's important is that this PIC and the other both have functions that need to work from the 5V line, and i'm not particularly looking forward to mucking about with it. Although the worst that could happen, realistically, is that that i can't get the PSU to boot up. When that happens i've spend all my money setting this up for it not to work.
Theory 1:
I want to also include a LCD display, probably a 20 by 4 character display, and run it from the USB port pins on the motherboard, so that i can send data to display down the USB port. I don't know if this is possible or not. I'm hoping it is, because if it isn't, then it puts a major bummer on my case mod.
What i need are ideas. Has anyone ever used PICs for this sort of thing? Any ideas about how to run my display? I would really like to know if there's a signal the motherboard sends out when shutting down, so i can perhaps get a 'dont power down the PSU till you get this line high' sort of line, which will give me time to close the fan controller doors and reset the analogue counters.
I know that this is as clear as muck, but what i need is someone to tell me if there's any fundamental flaws in my ideas, and if anyone knows anything about programming an LCD character display through the internal USB, i'd appreciate it greatly. I'd also appreciate any suggestions on how to get all this together-when i've got some of this sorted out i'll try and run up a sort of circuit diagram. I've got a book-PIC microprocessing, Bates-so i'm all set up for how to use the PIC, as well as having done a course in microelectronics. I've never used the PIC outside of the circuit tester though, so this is my first foray into actually using the PIC for something useful. I don't want to waste my time and money if i'm going to screw it all up, so i want to know from a like-minded group what they think of this.
-Dave