本帖最后由 Afanx 于 2022-10-31 14:12 编辑
窗口看门狗（WWDG）
时钟源：APB1时钟/4096
功能：7位递减计数器，具有上下限（0x7F~0x40）,当计数器小于0x40时产生复位，另外只能在计数器小于设定的窗口值才能对计数器重装载。
计数时间：PCLK1=36MHz
| 预分配 | 计数频率(Hz) | 步进时间(ms) | 最大计数时间(ms) | | 2^0 = 1 | 8.789k | 0.113 | 7.28 | | 2^1 = 2 | 4.394k | 0.227 | 14.56 | | 2^2 = 4 | 2.197k | 0.445 | 29.12 | | 2^3 = 8 | 1.098k | 0.910 | 58.25 |
软件配置流程：
1. 配置 RCC_APB1PCLKEN.WWDGEN[11]位使能 WWDG 模块的时钟
2. 软件设置 WWDG_CFG.TIMERB[8:7]位来配置 WWDG 的预分频因子
3. 软件配置 WWDG_CTRL.T[6:0]位，设置计数器的起始值。需要将 WWDG_CTRL.T[6]位设置为 1，以防止在启用后立即复位
4. 配置 WWDG_CFG.W[6:0]位配置上边界窗口值
5. 设置 WWDG_CTRL.ACTB[7]位使能 WWDG
6. 软件操作 WWDG_STS.EWINTF[0]位清除唤醒中断标志
7. 配置 WWDG_CFG.EWINT[9]位使能提前唤醒中断
配置代码：
- /**
- * [url=home.php?mod=space&uid=247401]@brief[/url] WWDG初始化
- */
- void WWDG_Initial(void)
- {
- /* Enable WWDG clock */
- RCC_EnableAPB1PeriphClk(RCC_APB1_PERIPH_WWDG, ENABLE);
- /* WWDG clock counter = (PCLK1(36MHz)/4096)/8 = 1099 Hz (~910 us) */
- WWDG_SetPrescalerDiv(WWDG_PRESCALER_DIV8);
- /* Set Window value to 80; WWDG counter should be refreshed only when the counter
- is below 80 (and greater than 64) otherwise a reset will be generated */
- WWDG_SetWValue(80);
- /* Enable WWDG and set counter value to 127, WWDG timeout = ~910 us * 64 = 58.25 ms
- In this case the refresh window is: ~910 us * (127-80) = 42.77 ms < refresh window < ~910 us * 64 = 58.25ms */
- WWDG_Enable(127);
- }
- /**
- * [url=home.php?mod=space&uid=247401]@brief[/url] WWDG测试
- */
- void WWDG_Task(void)
- {
- /* Check if the system has resumed from WWDG reset */
- if (RCC_GetFlagStatus(RCC_FLAG_WWDGRST) != RESET) {
- /* WWDGRST flag set */
- printf("\r\n reset by WWDG \r\n");
- /* Clear reset flags */
- RCC_ClrFlag();
- }
- /* Enable WWDG and set counter value to 127, WWDG timeout = ~910 us * 64 = 58.25 ms
- In this case the refresh window is: ~910 us * (127-80) = 42.77 ms < refresh window < ~910 us * 64 = 58.25ms */
- while (1) {
- /* Delay */
- DelayMs(50);
- /* Update WWDG counter */
- WWDG_SetCnt(127);
- /* Toggle LED */
- GPIO_ToggleBit(GPIOA, GPIO_PIN_8);
- }
- }
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