CYBT343026 的外部RTC 的晶振 型号推荐

[CaLi_4592466]

CYBT343026 我们这边外接了有源晶振，但是测试发现还是有挺大的误差，是否有你们厂家推荐的型号？精度比较高的。谢谢！

[BoonT_56]

This module already has a 24MHz crystal inside the module. It does not need an external crystal.

[CaLi_4592466]

内部的24mhz ，RTC 的时间误差很大。所以需要外接高精度的32K晶振。另外一个问题，当HIDOFF 唤醒后，系统时间会丢失吗？

[BoonT_56 · Accepted solution]

You may use parts from TXC, https://www.txccrystal.com/crystal.html

Size is probably your only consideration and our reference is a 3.2x.2.5x0.7 mm, and also 20ppm.

RTC is turned off during HIDOFF, therefore system time is reset.

[CaLi_4592466]

好的，谢谢！

我进入 HIDOFF 的模式代码如下：

/* Enable low power mode operation */

wiced_sleep_config( WICED_TRUE, 0, 0 );

/* Initialize the power save mode by passing the wakeup sources as the input parameter */

wiced_allow_sleep(TRUE);

wiced_power_save_start(WICED_WAKE_SOURCE_ALL, 60000);

我这样设置的wake up 时间，也会关闭RTC ？我需要 deep sleep 模式下，唤醒后RTC 不会重置系统时间怎么配置？

[Owen_Zhang123]

这个算是timed wakeup sleep，不会关闭rtc。HIDOFF比这个更彻底，所以会把rtc也关掉。

[CaLi_4592466]

那为什么唤醒后，起来后RTC 的时间会丢失？

[BoonT_56]

In HIDOFF, both LPO and RTC will be turned off.

In Timed-Wake, LPO and RTC are still active.

This is the definition for the two low power mode. Therefore if you specify 60s in your function call, then it is technically

a time-wake event, and not a hidoff.

[CaLi_4592466]

Thanks.

So Why dose the device wake up has a not right RTC time with Timed-wake Mode?

Please help me  use which API can make the right RTC when device wake  up.
I am using these code.

/* Enable low power mode operation */

wiced_sleep_config( WICED_TRUE, 0, 0 );

/* Initialize the power save mode by passing the wakeup sources as the input parameter */

wiced_allow_sleep(TRUE);

wiced_power_save_start(WICED_WAKE_SOURCE_ALL, 60000);

[Owen_Zhang123]

Please refer to the following thread: cyw20706 怎么同步系统时间

I have attached a project for the RTC in the timed wakeup mode. You need to do some configuration when the system wakes up.