I’m using the F303K8 to output 4x PWM waveforms, which are fed to 4x MOSFETS for dimming LED circuits. I quite happily wrote some code to loop a fade through Red-Yel-Grn-Cyn-Blu-Mag and repeat, which works just fine… RYGCBM code: #include "mbed.h" PwmOut redpwm(PA_8); PwmOut grnpwm(PA_9); PwmOut blupwm(PA_10); PwmOut whtpwm(PA_11); int a; int b; float z=0.01; int main() { redpwm.period_us(1000); //Set Red PWM period to 1ms grnpwm.period_us(1000); //Set Green PWM period to 1ms blupwm.period_us(1000); //Set Blue PWM period to 1ms whtpwm.period_us(1000); //Set White PWM period to 1ms z=0.05; //Set wait value whtpwm.pulsewidth_us(0); while(1){ for(a=0; a<=1000; a++) { b=1000-a; blupwm.pulsewidth_us(b); redpwm.pulsewidth_us(a); wait(z); } for(a=0; a<=1000; a++) { b=1000-a; redpwm.pulsewidth_us(b); grnpwm.pulsewidth_us(a); wait(z); } for(a=0; a<=1000; a++) { b=1000-a; grnpwm.pulsewidth_us(b); blupwm.pulsewidth_us(a); wait(z); } } } Then I decided to write a different bit of code to randomise a colour, hold it for a second, then fade to another random colour. I haven’t written the fade bit yet as I’ve discovered a very annoying problem. The red channel on PA_8 does not work when running this code, whereas it works just fine with the RYGCBM code above. I noticed the pins were floating a bit so have put pull-down resistors on each output but this hasn’t solved the problem – PA_8 is still dead while PA_9, PA_10 and PA_11 are fine. Random colour code: #include "mbed.h" PwmOut redpwm(PA_8); PwmOut grnpwm(PA_9); PwmOut blupwm(PA_10); PwmOut whtpwm(PA_11); int a; float z; int redval; int bluval; int grnval; int whtval; Serial pc(SERIAL_TX, SERIAL_RX); int main() { redpwm.period_us(1000); //Set Red PWM period to 1ms grnpwm.period_us(1000); //Set Green PWM period to 1ms blupwm.period_us(1000); //Set Blue PWM period to 1ms whtpwm.period_us(1000); //Set White PWM period to 1ms z=1; //Set wait value while(1){ redval = rand()%1001; bluval = rand()%1001; grnval = rand()%1001; whtval = rand()%1001; redpwm.pulsewidth_us(redval); grnpwm.pulsewidth_us(grnval); blupwm.pulsewidth_us(bluval); whtpwm.pulsewidth_us(whtval); pc.printf("R%d G%d B%d W%d ",redval,grnval,bluval,whtval); wait(z); } } I put the pc.printf command in there to output the colour values to a hyperterminal, so I could check that was working OK – it is. I have even changed the original code into the second bit of code, line by line, in an attempt to find the problem. In that instance, I found PA_8 stops working when I remove the for loops?!?!?! Very confusing! I've also tried moving the PWM from PA_8 to PA_12 and I still encounter the same problem. Can anyone help? This is driving me nuts!!

Not sure why the code formatting went all funny - Sorry about that!