Crystal Oscillator

Question

Hi, 
 I am using NRF52832 for my project. I need a support to handling oscillator 
 my project needs to reads the sensor raw data and through it in BLE_UART. and do calculation with timer, proximity, saadc 
 all this i need to work in ultra low power mode. how to control the power. 
 internal oscillator or external 32.768khz or 32Mhz . 
 which one is better. 
 and how to access only internal oscillator. is there any function; 
 please share some tutorials related to this oscillator.

bjorn-spockeli · Accepted Answer

Hi Sunil, 
 the clock sources are automatically managed on the nRF52832, i.e. the peripherals will enable/disable the required clock source. However, some peripherals require the 32MHz clock, e.g. the SAADC, TIMER, Serial Interfaces etc 
 The same goes for power management, it is automatically managed by the nRF52832, i.e power is routed to the peripheral if its enabled/initialized and cut if it is disabled/uninitialized. So whenever you're not using a peripheral it is important that you uninitialized said peripheral. 
 I recommend that you use the Timer library , which uses the RTC1 peripheral, which in turn uses the 32kHz oscillator which has a very low run current, 0.6uA if the LFRC is used and 0.25uA if an external 32kHz oscillator is used. 
 
 It is also possible to use the SAADC in low power mode by setting the .low_power field in the nrfx_saadc_config_t struct passed to nrfx_saadc_init . 
 NOte: The external 32kHz is optional as the nrf52832 can use the internal 32kHz RC oscillator, but the 32MHz oscillator is mandatory for using the RADIO as a Bluetooth Radio. 
 Best regards 
 Bjørn