ok ! its as simple as that
is there any special way you use the pwm outputs ?
thanks
The PWM output frequency is fixed 23.43kHz
You can only adjust the duty cycle.
The duty cycle is corresponding to the analog output voltage in the range 0…255
0 corresponds to duty cycle 0%
127 corresponds to duty cycle 50%
255 corresponds to duty cycle 100%
can you recommend a circuit that may take the output from a analogue vr sensor and convert it to digital so the k8055 can read it ?
i am having trouble getting the timer to read once the rpm gets up everyting works fine on low rpms
is there a minimum pulse width (or duty cycle ) the timer needs in order for it to register a count
[quote]is there a minimum pulse width (or duty cycle ) the timer needs in order for it to register a count[/quote]Yes, the pulse width (high and low) must be 0.25ms or more.
At the max. frequency 2kHz the duty cycle must be 50%.
To get this frequency counted the debouce time must be set to 0.
is there anything i can do to increase the pulse width of the signal ? add a capacitor across the terminals for example
i have written a lot of software to get this thing to work and it looks like the 8055 may not be up to the job
thanks in advance
[quote]add a capacitor across the terminals for example[/quote]This may help in some cases.
One alternative is to use a digital circuit (flip-flop) as a divider.
This way the duty cycle is always 50%.
the flip flop circuit sounds like a good idea
any idea’s where i can buy one
thank you
You may also use a divider.
It is very easy to connect: Needs +5V, GND, Input, Output and Reset pin to be connected.
You can get the input frequency divided by 2, 4, 8 etc.
The output duty cycle is always 50%.
There are many alternatives to select.
Here a link to a selection page:
ics.nxp.com/products/counters/pa … DIL&sub=02
A good choice may be this:
74HC4024 5V 7-Stage Binary Ripple Counter
On the page click the + sign next to 74HC4024 and then click More… to get more data.
There in the section “Pricing/ordering/availability” you’ll find where to buy.
Click “Buy online” to get more info.
Here an example:
http://search.digikey.com/scripts/DkSearch/dksus.dll?site=us&lang=en&mpart=74HC4024N%2c652
Hi I ordered up the 74hc4024D and it arrived today
pdf1.alldatasheet.com/datasheet- … 4024D.html
am i correct i attach the following,
pin 1 from switched rpm source
pin 7 gnd from switched rpm source
pin 14 + 5v
pin 3 to 8055 timer1
pn 7 gnd to 8055 timer gnd
thanks again for you assistance
Looks OK.
Also connect the pin 2 (master reset input) to GND.
The output pin 3 frequency is equal to the input frequency divided by 128.
This may be too low.
Maybe you can try first divide by 2 output (pin number 12).
If too high, you may use divide by 4 output (pin 11) etc…
dissapointingly I can’t get this flip flop circuit to work at all
i may have to drop the 8055 and try something else - or maybe use a frequency to voltage convertor
i will try a capacitor across the counter and ground
the capacitors i tried all seemed to reduce the rpm the trigger would read, it was better without
qu - can a resistor be changed on the board to make the 8055 read shorter pulse widths ?
perhaps i could use a optical sensor and make half the shaft white/black that way i would get a 50% duty cycle ?
[quote]dissapointingly I can’t get this flip flop circuit to work at all[/quote]This is strange.
[quote]qu - can a resistor be changed on the board to make the 8055 read shorter pulse widths ?[/quote]No, the limitation is based on the firmware.
[quote]perhaps i could use a optical sensor and make half the shaft white/black that way i would get a 50% duty cycle ?[/quote]This may be good solution to try.
i have a couple of these sensors
docs-europe.origin.electrocompon … 02e127.pdf
i am going to try one with a trigger that is 50% metal / 50% air
hoping it will do the job
(using it means i will not need a vr interface to convert to digital)
determined to get this to work !
thanks again for all the support
[quote]dissapointingly I can’t get this flip flop circuit to work at all[/quote]The cause to this may be that the output of the sensor is open collector. There is no output voltage from the sensor output. You need to add a pull-up resistor from the sensor output to the +5V.
[quote]i am going to try one with a trigger that is 50% metal / 50% air
hoping it will do the job[/quote] This should work with the K8055.
[quote]i have a couple of these sensors
docs-europe.origin.electrocompon … 02e127.pdf[/quote] The output of this sensor is open collector.
There are pull-up resistors on the K8055 card. No need for an external pull-up resistor in this case.
this is looking rather interesting
docs-europe.origin.electrocompon … b13a41.pdf
it will take an analogue output from a vr sensor and do many things with it
either output it as digital - can be used with the 8055 counter
or output a voltage - can be read by the 8055 (what is max volts the 8055 can read ?)
if you got to page 12 and look at the 4th image - it appears it will output like a flip flop
Indeed, looks interesting but may be quite difficult to get it working properly…
[quote]or output a voltage - can be read by the 8055 (what is max volts the 8055 can read ?)[/quote]The analog input voltage is +5V max.
i tried a 51 k resistor between the +5v resistor and the sensor output
still no pulse using the flip flop