CC3200 SDK中PWM例程 ，将分频系数0更改为1，定时器频率错误！

SDK中pwm频率为2KHz,将分频系数0更改为1，频率小于1kHZ。

只更改了MAP_TimerPrescaleSet(ulBase,ulTimer,1);  如下图

Viki Shi：

PWM模式下prescale不是分频器，注意模式不同，prescale的使用不同：

. Note that when counting down in oneshot or periodic modes, the prescaler acts as a true prescaler and contains the least-significant bits of the count. When counting up in one-shot or periodic modes, the prescaler acts as a timer extension, and holds the most-significant bits of the count. In input edge count, input edge time, and PWM mode, the prescaler always acts as a timer extension, regardless of the count direction.

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user6314671：

那具体怎么使用才能增加定时器时间间隔？让cc3200 输出频率更低的pwm

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Viki Shi：

时间间隔基于如下计算：

//
// The PWM works based on the following settings:
//Timer reload interval -> determines the time period of one cycle
//Timer match value -> determines the duty cycle//range [0, timer reload interval]
// The computation of the timer reload interval and dutycycle granularity
// is as described below:
// Timer tick frequency = 80 Mhz = 80000000 cycles/sec
// For a time period of 0.5 ms,//Timer reload interval = 80000000/2000 = 40000 cycles
// To support steps of duty cycle update from [0, 255]
//duty cycle granularity = ceil(40000/255) = 157
// Based on duty cycle granularity,
//New Timer reload interval = 255*157 = 40035
//New time period = 0.5004375 ms
//Timer match value = (update[0, 255] * duty cycle granularity)
//
#define TIMER_INTERVAL_RELOAD40035 /* =(255*157) */
#define DUTYCYCLE_GRANULARITY157