MAX32660 Examples TMR

[tk2themax]

On build for MAX32660, TMR example project warns "function call is not allowed in a constant expression" on line 72(Main)

Guidance suggests that The error "function call is not allowed in a constant expression" typically occurs when you try to use a function call in a context where a compile-time constant is expected

Although this does not stop the build/compile, there is a possible linked manifestation of this in that when the DUTY_CYCLE, as DEFINED in Main(line46), value is changed in the source and recompiled and flashed, the physical PWM duty cycle on TMR GPIO 3.7 PIN does not actually change from the 50% originally set. However, when FREQ is changed (line 45), and recompiled, flashed, the frequency does change as expected.

This suggests that there is a value being set for DUTY_CYCLE which, once set is not cleared and reassigned any given new value on recompile.

CLEAN_PERIPH on build/flash did not alleviate.

[Jake-Carter]

Thanks @tk2themax,

I think the issue was just that the DUTY_CYCLE macro was just never actually used in the example...

Can you try the fix below and confirm?

 #include "led.h"
 
 /***** Definitions *****/
-#define MAX_TICKS pow(2, 32)
+#define MAX_TICKS 4294967296
+// 2^32
 
 // Parameters for PWM output
 #define FREQ 1000 // (Hz)
@@ -77,7 +78,7 @@ void PWMTimer(void)
     // Declare variables
     mxc_tmr_cfg_t tmr; // to configure timer
     unsigned int periodTicks = MXC_TMR_GetPeriod(PWM_TIMER, 1, FREQ);
-    unsigned int dutyTicks = periodTicks / 100 * 50;
+    unsigned int dutyTicks = periodTicks * (DUTY_CYCLE / 100.0f);
 
     //Configure PWM GPIO Pin
     mxc_gpio_cfg_t pwmOut;

[tk2themax]

Oh my - I missed that ! But at least there was a problem - even if my diag was off ! Thanks - all good now with this fixes.