AnsweredAssumed Answered

Using PWM on GPIO on MPR121

Question asked by Paul Wilson on Mar 25, 2013
Latest reply on Jul 6, 2017 by DJ Mitch



I am using an MPR121 with 5 touch pads and 5 LED outputs. The LED outputs are on lines LED1, LED2, LED3, LED3, LED5. I can turn all 5 LEDs on and off with the set and clear registers. However, when I attempt to use PWM on the LED outputs, LEDs 1 through 4 operate as expected but LED5 does not. Specifically, if the PWN is turned off (corresponding PWN nibble = 0), I can turn LED5 on and off but if I set the corresponding PWN nibble to any value other than 0, the LED is not illuminated. I have confirmed that there is no signal at all on LED under that condition by means of an oscilloscope. Does anyone else have any experience using the GPIO outputs on the MPR121 with PWM? If so, any ideas as to why I cannot get it to work for LED5.