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1.优化PWM定时器PSC和ARR计算算法，大幅提升计算效率（通常只需迭代2-3次），优先逼近目标频率，并在误差允许范围内（万分之一到百分之一，误差范围随目标频率提高而增加）获得最佳的占空比分辨率。

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2.PWM-info中clk从MHz改为Hz。
This commit is contained in:
MacRsh
2024-01-20 04:04:34 +08:00
parent 3d6344a090
commit 182de531ca
3 changed files with 35 additions and 47 deletions
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76
device/pwm.c
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@@ -65,74 +65,62 @@ static int pwm_channel_get_configure(struct mr_pwm *pwm, int channel, struct mr_
static int pwm_calculate(struct mr_pwm *pwm, uint32_t freq)
{
uint32_t clk = pwm->info->clk, psc_max = pwm->info->prescaler_max, per_max = pwm->info->period_max;
uint32_t psc_best = 0, per_best = 0;
uint32_t psc_best = 1, per_best = 1;
int error_min = INT32_MAX;
/* Check the clock */
/* Check the clock and frequency */
if (clk == 0 || freq == 0)
{
return MR_EINVAL;
}
/* Calculate the timeout */
uint32_t timeout = (clk * 1000000) / freq;
/* Calculate the prescaler and period product */
uint32_t product = clk / freq;
/* Calculate the Least error period */
for (uint32_t per = (timeout <= per_max) ? timeout : (timeout / (per_max + 1)); per > 0; per--)
/* If the product is within the maximum period, set it as the period */
if (product <= per_max)
{
uint32_t psc = timeout / per;
/* Calculate the error */
int error = (int)timeout - (int)(psc * per);
if (error == 0)
{
psc_best = psc;
per_best = per;
break;
}
if (error <= error_min)
{
error_min = error;
psc_best = psc;
per_best = per;
}
}
/* Optimize the prescaler and period */
for (uint32_t divisor = 9; divisor > 1; divisor--)
psc_best = 1;
per_best = product;
} else
{
/* Check if reload value can be divided by current divisor */
while ((psc_best % divisor) == 0)
/* Calculate the Least error prescaler and period */
for (uint32_t psc = MR_BOUND(product / per_max, 1, psc_max); psc < psc_max; psc++)
{
uint32_t per_temp = per_best * divisor;
uint32_t per = MR_BOUND(product / psc, 1, per_max);
/* Check if new period or prescaler is valid */
if (per_temp <= per_max)
{
per_best = per_temp;
psc_best /= divisor;
} else
{
break;
}
/* Calculate the frequency error */
int error = (int)freq - (int)(clk / psc / per);
/* Check if prescaler can be used as period */
if ((psc_best > per_best) && (psc_best < per_max))
/* Found a potentially optimal prescaler and period combination */
if (error == 0)
{
MR_SWAP(per_best, psc_best);
psc_best = psc;
per_best = per;
/* Found a valid and optimal solution */
if (per_best < per_max)
{
break;
}
} else if (error < error_min)
{
error_min = error;
psc_best = psc;
per_best = per;
}
}
}
/* Check prescaler is valid */
if (psc_best > psc_max)
/* Check period is valid */
if (per_best > per_max)
{
return MR_EINVAL;
}
pwm->prescaler = psc_best;
pwm->period = per_best;
pwm->freq = (clk * 1000000) / psc_best / per_best;
pwm->freq = clk / psc_best / per_best;
return MR_EOK;
}