PulsIn - Bs2 Got it
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Okay, I took the easy way out for now.
15 volt PWM Signal coming in and being clamped by a 3.9 zener (what I
had on hand) Stamp reads it and outputs a signal to a RC Network.
Works Perfect, Dead On. Voltage out X 2 = Duty Cycle
I just need the duty cycle indication withing a percent or two so
even if the stamp regulator difts a little it will not hurt me too
bad. Mainly reference readings.
======================================================================
===
' File: FREQ2.BS2
'
' Counts and displays frequency of pulses arriving on Pin 0
'
======================================================================
===
F_pin CON 7 ' frequency
input pin
VOut CON 6
pHigh VAR Word ' W3 high
pulse width
pLow VAR Word ' W2 low
pulse width
period VAR Word ' cycle time (high +
low)
freq VAR Word ' frequency
T2 Var word
T3 var word
duty var word
'
Output 6
Loop:
PULSIN F_pin, 0, pHigh ' get high portion of
input
PULSIN F_pin, 1, pLow ' get low portion of
input
period = pHigh + pLow ' calculate cycle
width
t2 = plow
t3 = phigh
t3 = t2 + t3
t3 = t3 / 10
t2 = t2 * 10
t2 = t2/t3
freq = 50000 / period * 10 ' calculate frequency
' display on DEBUG screen
DEBUG Home
DEBUG "Period...... ", DEC period * 2, " uS ", CR
DEBUG "Frequency... ", DEC freq, " Hz ", CR
DEBUG "Duty Cycle ..", Dec t2, "% "
t2 = t2 * 255
t2 = t2 / 100
PWM VOut, t2,150 ' output voltage
porportional to duty cycle (voltage * 2 = duty cycle
GOTO Loop ' do it again
--- In basicstamps@yahoogroups.com, smartdim@a... wrote:
> You may want to consider a MAX5101 DAC.
>
> It has rail to rail output. It has 3 outputs selected by two lines.
>
> If you run it on 5 volts, you can then easily amplify by two for a
0 to 10v output, 5 volts = 50% duty, 7.5 volts 75% etc.
>
> Or if you run it on 10 volts you have 0 to 10 volt output. A cheap
and dirty DAC can be made with a thing called and R2R resistor
network. It is I/O pin hungry though (8 pins), but you can use a
shift register and get away with only 3 pins.
>
> Ken
15 volt PWM Signal coming in and being clamped by a 3.9 zener (what I
had on hand) Stamp reads it and outputs a signal to a RC Network.
Works Perfect, Dead On. Voltage out X 2 = Duty Cycle
I just need the duty cycle indication withing a percent or two so
even if the stamp regulator difts a little it will not hurt me too
bad. Mainly reference readings.
======================================================================
===
' File: FREQ2.BS2
'
' Counts and displays frequency of pulses arriving on Pin 0
'
======================================================================
===
F_pin CON 7 ' frequency
input pin
VOut CON 6
pHigh VAR Word ' W3 high
pulse width
pLow VAR Word ' W2 low
pulse width
period VAR Word ' cycle time (high +
low)
freq VAR Word ' frequency
T2 Var word
T3 var word
duty var word
'
Output 6
Loop:
PULSIN F_pin, 0, pHigh ' get high portion of
input
PULSIN F_pin, 1, pLow ' get low portion of
input
period = pHigh + pLow ' calculate cycle
width
t2 = plow
t3 = phigh
t3 = t2 + t3
t3 = t3 / 10
t2 = t2 * 10
t2 = t2/t3
freq = 50000 / period * 10 ' calculate frequency
' display on DEBUG screen
DEBUG Home
DEBUG "Period...... ", DEC period * 2, " uS ", CR
DEBUG "Frequency... ", DEC freq, " Hz ", CR
DEBUG "Duty Cycle ..", Dec t2, "% "
t2 = t2 * 255
t2 = t2 / 100
PWM VOut, t2,150 ' output voltage
porportional to duty cycle (voltage * 2 = duty cycle
GOTO Loop ' do it again
--- In basicstamps@yahoogroups.com, smartdim@a... wrote:
> You may want to consider a MAX5101 DAC.
>
> It has rail to rail output. It has 3 outputs selected by two lines.
>
> If you run it on 5 volts, you can then easily amplify by two for a
0 to 10v output, 5 volts = 50% duty, 7.5 volts 75% etc.
>
> Or if you run it on 10 volts you have 0 to 10 volt output. A cheap
and dirty DAC can be made with a thing called and R2R resistor
network. It is I/O pin hungry though (8 pins), but you can use a
shift register and get away with only 3 pins.
>
> Ken
Comments
skinner02001@y... writes:
Okay, I took the easy way out for now.
15 volt PWM Signal coming in and being clamped by a 3.9 zener (what I
had on hand) Stamp reads it and outputs a signal to a RC Network.
Works Perfect, Dead On. Voltage out X 2 = Duty Cycle
I just need the duty cycle indication withing a percent or two so
even if the stamp regulator difts a little it will not hurt me too
bad. Mainly reference readings.
________________________________________________________-
Just curious, is the 15 PWM signal buffered before you clamp it with the
zener? Is the solenoid still able to receive full battery voltage?
A word of caution.......
If you have an oscope, I would suggest you look at the "zener clamped" duty
signal. Zener diodes are not particularly fast devices. There may be momentary
spikes greater that 5 volts until the zener clamps. Over time, the momentary
spikes (if they are there ) in time will likely damage that stamp input pin.
Cool project.....I recently did the same, but with a different uP (SX28). It
has a two digit display and analog output that is fed to a data logger. We use
it at my work to look at the duty cycle of transmission lock up solenoids,
and pressure control solenoids on competitor vehicles.
[noparse][[/noparse]Non-text portions of this message have been removed]
I'm also changing the entire signal going to the Engine computer as
well. I'll go ahead and look at the Buffers and be done with it. At
least I was able to breadboard it all out and make sure it would work
fine (software). I had planned on having two digits as well to
display 0-99 on top for a visual reference by using a couple of bcd
drivers, but then I decided I would do multiple channels on one chip.
Once up and going, I'm moving over the the 16F84.
Thanks,
Richard
--- In basicstamps@yahoogroups.com, smartdim@a... wrote:
> In a message dated 9/16/2003 7:07:27 PM Pacific Daylight Time,
> skinner02001@y... writes:
> Okay, I took the easy way out for now.
>
> 15 volt PWM Signal coming in and being clamped by a 3.9 zener (what
I
> had on hand) Stamp reads it and outputs a signal to a RC Network.
> Works Perfect, Dead On. Voltage out X 2 = Duty Cycle
> I just need the duty cycle indication withing a percent or two so
> even if the stamp regulator difts a little it will not hurt me too
> bad. Mainly reference readings.
> ________________________________________________________-
>
> Just curious, is the 15 PWM signal buffered before you clamp it
with the
> zener? Is the solenoid still able to receive full battery voltage?
>
> A word of caution.......
>
> If you have an oscope, I would suggest you look at the "zener
clamped" duty
> signal. Zener diodes are not particularly fast devices. There may
be momentary
> spikes greater that 5 volts until the zener clamps. Over time, the
momentary
> spikes (if they are there ) in time will likely damage that stamp
input pin.
>
> Cool project.....I recently did the same, but with a different uP
(SX28). It
> has a two digit display and analog output that is fed to a data
logger. We use
> it at my work to look at the duty cycle of transmission lock up
solenoids,
> and pressure control solenoids on competitor vehicles.
>
>
> [noparse][[/noparse]Non-text portions of this message have been removed]