How to change the RTC clock source?

[yuda-hanlong]

I want to use an external 32.768khz clock source for the module clock source
The scene is an interval of 60 seconds for module to automatically wake up, and then get into the deep_sleep.
But in the arduino environment called rtc_clk_32k_enable ( true ) ; and rtc_clk_slow_freq_set ( rtc_slow_freq_32k_xtal ) ;I set into deepleep and after 60 seconds to wake up, but the actual almost 5 minutes or so before awakening.
How can i do "How long I want to time it, how long I actually sleep"