Remote Vehicle Starter Help

[b1arrk5]

I used a voltage divider. For my test circuit, I had the ADC continuously read the voltage, and send the result out the serial port. With my laptop watching the serial port, I started the car, and had before and after battery voltage readings. Merry Christmas,Jerry

[amgen]

Cool deal, my guess about voltages is about 8 volts cranking and jumps to 12 to 12.8 when first starts ? A rare problem with that setup is a dying battery that sits at rest at 12 volts but when starter enguages, the voltage dips so low that the starter drops out and the voltage goes up then repeats that chatter in and out. Not sure how you would detact that. Timmers may have thought of that but with more circuitry.
Don

[Art]

I'm not having any luck using the ACD of a 16F877A.
Maybe I should have given the thing a better output than a flashing light,
but I'm pretty sure I'm getting a zero reading every time.
The circuit always waits for the timeout to stop the starter motor.

if anyone likes to take a look...

' Remote start controller
'  for '92 Toyota Surf
'
DEFINE OSC 04                            'hardware is using a 4MHz crystal
DEFINE ADC_BITS 10                        '10 bit ADC for 16F877A
'
adcon1.0 = 1 : adcon1.3 = 1                'set porte pins digital
trise.0 = 1 : trise.2 = 1                'set porte pins as inputs
trisb.1 = 1 : trisb.2 = 1                'set portb pins as inputs
trisd.2 = 1    : trisd.3 = 1                'set portd pin as input
trisa.0 = 1 : trisa.1 = 1                'set all analogue channels as inputs
trisa.2 = 1 : trisa.3 = 1                '
ADCON1 = 0                                'set analogue inputs
ADCON1.7 = 1                            'right justified for 10 bit ADC
'
seq var byte                            'run sequence flag
timea var byte                            'time lsd
timeb var byte                            'time msd
timec var byte                            'timer
timed var byte                            'timer
timee var byte                            'timer
xtimed var byte                            'timer
xtimee var byte                            'timer
debouncea var byte                        'input a debounce counter
debounceb var byte                        'input b debounce counter
debouncec var byte                        'input c debounce counter
srelay var byte                            'starter relay status
irelay var byte                            'ignition relay status
bvoltage var word                        'battery voltage value
avoltage var word                        'running voltage value
ttiimmee var byte                        'timer
held var bit                            'button held flags
xheld var bit                            '
rlock var bit                            '
gosub reset                                '
'
'
main:
if timeb > $04 then                        '
'
if srelay = 0 then                        '
high portb.5                            'led on
else                                    '
low portb.5                                'led off
endif
endif                                    '
pauseus 500                                'delay
if irelay = 0 then                        '
low portb.5                                'led off
endif                                    '
'
timea = timea + 1                        'increment timer
if timea = $FF then                        '
timeb = timeb + 1                        '
timea = 0                                '
endif                                    '
'
if timeb = $06 then                        'check timer
if timec < $F0 then                        '
timec = timec + 1                        '
endif                                    '
timeb = 0                                'reset timer
endif                                    '
'



'
'
if debouncea < $F9 then                    'increment debounce a timer
debouncea = debouncea + 1                '
endif                                    '
if debounceb < $F9 then                    'increment debounce b timer
debounceb = debounceb + 1                '
endif                                    '
if debouncec < $F9 then                    'increment debounce c timer
debouncec = debouncec + 1                '
endif    
'
if debouncea = $F9 then                    '
if portb.1 = 0 then                        'ignition off button, yellow wire
seq = 0                                    'end sequence
irelay = 0                                'turn relays off
srelay = 0                                '
gosub reset                                '
endif                                    '
endif                                    '
'
if debounceb = $F9 then                    '
if portb.2 = 0 then                        'violet wire... unlock button
debounceb = $F8                            '
held = 1                                '
timed = timed + 1                        '
if timed = $FE then                        '
timed = 0                                '
timee = timee + 1                        '
endif                                    '
endif                                    '
if portb.2 = 1 then                        '
held = 0                                '
timed = 0                                '
timee = 0                                '
debounceb = 0                            '
endif                                    '
if timee > $09 then                        'unlock button held delay define here
timed = 0                                '
timee = 0                                '
debounceb = 0                            '
held = 0                                '
seq = 1                                    'activate sequence
timec = 0                                '
endif                                    '
endif                                    '
'
if debouncec = $F9 then                    '
if portd.2 = 0 then                        'blue wire... lock button
debouncec = $F8                            '
xheld = 1                                '
xtimed = xtimed + 1                        '
if xtimed = $FE then                    '
xtimed = 0                                '
xtimee = xtimee + 1                        '
endif                                    '
endif                                    '
if portd.2 = 1 then                        '
xheld = 0                                '
xtimed = 0                                '
xtimee = 0                                '
debouncec = 0                            '
endif                                    '
if xtimee > $09 then                    'lock button held delay define here
xtimed = 0                                '
xtimee = 0                                '
debouncec = 0                            '
seq = 0                                    'end sequence
rlock = 0                                '
irelay = 0                                'turn relays off
srelay = 0                                '
gosub reset                                '
endif                                    '
endif                                    '
'
if seq = 1 then                            '
irelay = 1                                'turn on ignition power relay
if timec = 02 then                        '
srelay = 1                                'turn on starter motor relay
endif                                    '
'
if srelay = 1 then                        '
'
ttiimmee = ttiimmee + 1                    'increment timer
if ttiimmee = 70 then                    'time between samples is set here
ADCIN 0, avoltage                        'read running voltage
if avoltage > bvoltage + 1 then            'detect vehicle start
srelay = 0                                'turn off starter motor
endif                                    '
ttiimmee = 0                            '

bvoltage = avoltage                        'remember old voltage reading


endif                                    '
'
if portb.2 = 0 then                        '
timec = $03                                '
timeb = $02                                '
rlock = 0                                '
srelay = 0                                '
low portd.1                                '
pause 1000                                '
endif                                    '
endif                                    '
'
if timec = $03 then                        'starter motor on time defined here
if timeb = $03 then                        '
rlock = 0                                '
srelay = 0                                'turn off starter motor
endif                                    '
endif                                    '
'
endif                                    '
'
if seq = 0 then irelay = 0                'turn off ignition power relay
'
'
if srelay = 0 then                        'set starter relay state to starter relay flag
rlock = 0                                '
low portd.1
else
high portd.1
endif
'
if irelay = 0 then                        'set ignition relay state to ignition relay flag
low portd.0
else
high portd.0
endif
'
goto main                                'repeat main loop
'
'
reset:
srelay = 0 : irelay = 0                    'reset relay status for start program
timea = 0 : timeb = 0                    'reset timer variables for start program
timec = 0 : timed = 0                    '
timee = 0 : ttiimmee = 0                '
xtimed = 0 : xtimee = 0                    '
debouncea = 0 : debounceb = 0            'reset debounce timers
debouncec = 0                            '
held = 0 : xheld = 0                    'reset flag
avoltage = 0 : rlock = 0                '
bvoltage = 65533                        '
low portd.1 : low portd.0                'start with relays off hardware controlled
seq = 0                                    '
return                                    '
'
'
'
'
'

Cheers, Art.

[mackrackit]

This sorta conflicts
adcon1.0 = 1 : adcon1.3 = 1 'set porte pins digital
With This
ADCON1 = 0 'set analogue inputs
ADCON1.7 = 1 'right justified for 10 bit ADC
But the last two lines should be OK. See register 11-2 in the data sheet.

Not sure I follow this:
ADCIN 0, avoltage 'read running voltage
if avoltage > bvoltage + 1 then 'detect vehicle start
avoltage will not be greater than 1023.. 10 bit
Then there is this
bvoltage = 65533

[Art]

I'll have to look at the ADCON1 register. I think there is some insight for me there.

The initial value for bvoltage is set higher than any 10 bit reading can be so the flag is not triggered on the first cycle.
It could just as easily be 1024, but it's a 10 bit value stored in a 16 bit word var, so I can use a higher number.

bvoltage is the last reading stored for X number of cycles to be compared to the current value which is avoltage.
If no branch condition is met, then the current value becomes the last value for comparison the next time.

[b1arrk5]

I'll try to see if I can find some code. I've been doing Arm7 C programming the last two years, so I have to dig out my old basic files. My code worked well in two Ford vehicles, and I drove them both through a full winter using the starter every cold winter morning! I built the first one on a Lab-x board from melabs, it has an LCD to show whats happening, but the output to the laptop was safer for testing because I had history to look at after I drove the car.If the initial battery voltage was about 11 vdc, the processor would refuse to try to start the engine. I typically see 12.4 to 12.8 before the starter engages, and 13.8 or so as soon as the starter is disengaged. Happy New Year!Jerry

[mister_e]

Happy new year y'all!

I've installed remote car starter for 12 years and there's quite a few method you can use if you don't have any Tach signal generated by the Alternator, available on the Cluster connector or ECM.

The oldest method in early 90's
1) use a vacuum switch...
Con:
not always easy and doable to find a proper vacuum source/hose,
need to cut the hose, and take chance the switch could freeze

The next most popular in those years
2) read the Battery voltage, should be 'round 13.8ish V when the vehicle is started
Con:
Starter often stay engaged when not properly implemented or with "Soon to die" alternator

The most valuable and still in use solutions are
1) use a Field effect sensor attached on the top of the alternator.
Easy to implement, but some alternator do not generate enough magnetic field, OR have their own
"Strong Sweet spot", so you may have to monitor it to find the sweet spot. And once you find it, sometime it's just not simple to sit your detector there. You also need to route more wires.

2) read the Alternator output, the wire that goes "High" when the vehicle is started
The easiest solution, easy to implement with an averaged ADCIN routine (plus some extra pause and double/triple check) and a really strong power supply, board and noise filtering design. The safest and easiest in the installation field. Most alternator have this specific output.

3) grab the junk generated by the alternator on the 12V line and use it as "Tach" signal
Really popular available and patented by many car starter brand. If properly designed it works a treat for all type of car, truck, everything and do not require any extra wiring.

Enjoy, back to my batcave.