Remote Vehicle Starter Help

[timmers]

I built an auto starter for a generator.
Used a hall effect sensor looking at the starter teeth of the flywheel. Fed this into TIMER 1 external clock input, and used it to count the number of pulses (teeth) over a time period. I then did some tests and measured the fastest it could crank when warm, then set a threshold about 20% higher. Never had a problem with it.

For the record, I built in lots of safety features, which included low voltage cutout, under speed cranking, low oil pressure, over temperature, with visual and audible warnings before starting and an emergency stop switch.

I was able to have a remote control panel in the house where I could display and configure the parameters or manually start the engine and switch over the electric contactors. Never used it in manual, auto was fine.

[Art]

I can understand why people would do this with generators. Who wants to walk outside to start an engine

My alternator may not produce voltage straight away (although I'm pretty sure it does),
I am able to see an initial voltage, then a drop while cranking, then a gradual rise to a higher voltage.

I think this is nice because I should be able to use the supply leg of the 7805 to take
the voltage measurement, and need no extra wires.

[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.