Jovica D.

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11 years ago.

PWM BUG?

Hello,

is there a bug with PWM??

Connect to your mbed Microcontroller with a Terminal program and uses the 'u' and 'd' keys to make LED1 brighter or dimmer

  1. include "mbed.h"

Serial pc(USBTX, USBRX); tx, rx PwmOut led(LED1);

float brightness = 0.0;

int main() { pc.printf("Press 'u' to turn LED1 brightness up, 'd' to turn it down\n");

while(1) { char c = pc.getc(); if((c == 'u') && (brightness < 0.5)) { brightness += 0.01; led = brightness; } if((c == 'd') && (brightness > 0.0)) { brightness -= 0.01; led = brightness; }

} }

The syntax is correct but on my terminal i get the message "pinmap not found for peripheral" and the 4 LEDs toggel... NO PWM.

Whats the Problem here?

Thank you

Question relating to:

Last updated: 30 Apr 2020

2 Answers

Jovica D.
poster
11 years ago.

no bug :S the controller doesn't have PWM

David Golz
11 years ago.

Hi, are you sure the LPC11U24 has no PWM? It looks like there are several pins for PWM, but NOT the LEDs: http://mbed.org/handbook/PwmOut#lpc11u24

Hey David,

i search in the Dokumentation of LPC11U24, this controller doesn't have PWM... but i'm not realy shure. In the exampel the PWM Pin LED1 is modulating but if i do this all LEDs are toggeling.

the Handbook isn't realy a helb becaouse he did PWM with Timers.

Thanks for answare

posted by Jovica D. 16 Apr 2013

David is correct, the 11U24 does have a PWM unit, just not for the LEDs.

posted by Erik - 16 Apr 2013

Jovica connect an external LED with series resistant to a pin with PWM e.g. Pin5 and set line 3 of the example to PwmOut led(p5);

posted by David Golz 17 Apr 2013

Thank you David

posted by Jovica D. 17 Apr 2013