PWM component
Hi,
I am new to the forum and to Basic Stamp. I am looking for a pwm component that I could use with the BS2 (such as the pwmpal) but I need to be able to change frequency (from 10000 Hz to 25000 Hz with step of 100 Hz) and the duty cycle (1 to 99%) on every frequency. I need the duty cycle to be changed on the low (0) phase to avoid blinking (I am controlling led light).
Thanks for your help
Chris
I am new to the forum and to Basic Stamp. I am looking for a pwm component that I could use with the BS2 (such as the pwmpal) but I need to be able to change frequency (from 10000 Hz to 25000 Hz with step of 100 Hz) and the duty cycle (1 to 99%) on every frequency. I need the duty cycle to be changed on the low (0) phase to avoid blinking (I am controlling led light).
Thanks for your help
Chris
Comments
Chris
For the ones interested, I find a work around. I had to use 4 components + the BS2 :
LM555 (RS 534-3469) as a pulse position modulator and DAC LTC 1257 to modulate 0-5 V and change the duty cycle
LTC 6900 (RS 506-2176) and a digital potentiometer to change the frequency.
It's working great and I get the smooth transition when dimming the leds I was looking for and couln't get with PWMPAL
Thanks again
I have no idea what you mean but it sounds ingenious!
Can you post your circuit and an explanation if you think it will work for me ?
I am trying to use the PWM Pal to generate smooth frequencies for my cars ecu, however everytime I change the frequency I get a re-triggering effect which causes a glitch depending when the change cuts in.. The PWMPal is not smart enough to wait until the last pulse has finished..
Just out of curiosity, why do you need to change the frequency? Doing so will not affect the apparent brightness of the LED; only a change in duty cycle will do that.
-Phil
You are right but I need to light leds through inductive coupling. I look for the right frequency for the coupling then I need to change the duty cycle to be able to dim the leds.
Chris