Can we do this? (aka The DIY Cruise Control Thread)

[nickhjort]

Total running tally for this mod so far:
$9.50 for two black switches, two packs of resistors, and the little LED mount thingies
$3.50 for pack of 4 switches for the clutch switch
$???? for the LED light module (soon to be completed by CTScott)

Also include the cost of wire, some spade connectors, soldering stuff, electrical tape, all of which I already had.

[CTScott]

Originally Posted by nickhjort

Total running tally for this mod so far:
$9.50 for two black switches, two packs of resistors, and the little LED mount thingies
$3.50 for pack of 4 switches for the clutch switch
$???? for the LED light module (soon to be completed by CTScott)

Also include the cost of wire, some spade connectors, soldering stuff, electrical tape, all of which I already had.

I just road tested the LED driver module on my 09. Having the indicators on the combination meter was quite handy. It took a couple of rounds of the PIC firmware to get the switch debouncing correct. I am shipping it to you today. Below are a couple of pictures (the PCB and the packaged module). I will post the schematic when I have a chance. The module hardware is fairly simple; basically a Microchip PIC12HV615 microcontroller (with built-in shunt regulator), 9 resistors, and a NPN transistor. The PIC microcontroller monitors the switch input via one of its analog to digital inputs. This lets it sense the difference between the on/off switch and the other switches. The PIC "HV" series microcontrollers have a built-in regulator which allows them to operate off of an unregulated power supply, eliminating the need for a voltage regulator.






As you can see from the labels, there are three connections:

1. Switch Input - This input gets connected to the wires going from the ECM and ground to the switches (Red to CCS and Black to ground).

2. LED Output - This output drives the Cruise Control on/off LED. This supplies 12 VDC, so it is intended to drive a panel mount LED with a built-in resistor.

3. +12 VDC power input (IG switched) - This wire gets connected to an ignition switched 12 volt source. The easiest place to connect to is the pink wire on the ignition switch connector.



This module will work with the DIY switches or with an OEM cruise stalk. I am shipping nickhjort's for no charge in appreciation for him being the guinea pig for this mod. If anyone else is interested in a completed module, I would probably need to charge $25 shipped to cover the parts cost (with the silly little box being the most expensive component) and labor to assemble.

[PatrickJohnson]

I'd love to see a schematic. I would be willing even to have some PCBs etched for people as drop-ins. Does this just drive the On/OFF LED? What about the SET light?

EDIT: I see you mentioned it can sense the difference between the switches, so I assume this drives both LED's. Again though, if you post the schematic I can etch actual circuit boards (instead of perfboard) for you or anyone else if there is interest.

[CTScott]

Originally Posted by PatrickJohnson

I'd love to see a schematic. I would be willing even to have some PCBs etched for people as drop-ins. Does this just drive the On/OFF LED? What about the SET light?

EDIT: I see you mentioned it can sense the difference between the switches, so I assume this drives both LED's. Again though, if you post the schematic I can etch actual circuit boards (instead of perfboard) for you or anyone else if there is interest.

It just drives the power LED. Because the switches are all paralleled together, the ADC is required to differentiate the on/off switch from the other three.

The problem with driving a SET LED, based on just the switch, is that there are too many conditions where you could press the switch, but not really be "set". Tonight I should have a chance to drop the schematic into ORCAD. If there was enough interest in the modules I figured I would do a run of boards.

[PatrickJohnson]

Originally Posted by CTScott

It just drives the power LED. Because the switches are all paralleled together, the ADC is required to differentiate the on/off switch from the other three.

The problem with driving a SET LED, based on just the switch, is that there are too many conditions where you could press the switch, but not really be "set". Tonight I should have a chance to drop the schematic into ORCAD. If there was enough interest in the modules I figured I would do a run of boards.

I see. pretty cool either way. I was thinking of just doing a cmos flip flop switch to run the LED. I figured I could use the connection made by the on/off to touch a flip flop circuit or a relay and reset it's state, turning on the LED. of course, that might be using a sledgehammer to drive a thumb tack :)

[CTScott]

Originally Posted by PatrickJohnson

I see. pretty cool either way. I was thinking of just doing a cmos flip flop switch to run the LED. I figured I could use the connection made by the on/off to touch a flip flop circuit or a relay and reset it's state, turning on the LED. of course, that might be using a sledgehammer to drive a thumb tack :)

I started off thinking I would use a flip flop, but you can't drive anything unless you change to a switch with a second set of contacts and you also have to maintain a high impedance to not confuse the ECM. The microcontroller is definitely overkill, but they are under $2.

[Sir A.Y. Atoyot]

For controlling an indicator light- has anyone considered a DPST switch for on-off? Wouldn't work for the stock cruise switch, of course, but it should be OK for the improvised setups. Too simple?

[CTScott]

Originally Posted by PatrickJohnson

I'd love to see a schematic. I would be willing even to have some PCBs etched for people as drop-ins. Does this just drive the On/OFF LED? What about the SET light?

EDIT: I see you mentioned it can sense the difference between the switches, so I assume this drives both LED's. Again though, if you post the schematic I can etch actual circuit boards (instead of perfboard) for you or anyone else if there is interest.

Here's the schematic:

[mg_xpower]

Nice work. Please consider the fact a car power supply is really "dirty". You'll have to take bursts and surges into account. I'd add a nice big elco to VDD (at least 100uF 35V) and a 100nF 50V X5R/X7R ceramic capacitor close to the controller.

Are you measuring battery voltage at p6 ? -> Add 100nF over R7.