NRF51822 Lower Power Mode with RTC wakeup

[liu]

Hi,

I have a question that Product Specification v3.1 of nrf51822 describes Flexible Power Management: 2.6 μA at 3 V ON mode, all blocks IDLE. But, in the same place, NRF52832 describes as follows: 1.9 μA at 3 V in ON mode, no RAM retention, wake on RTC.

So i wonder if i cann't use RTC to wake nrf51822 in lower power mode(use power_manage()).

[Chocol8]

Hello, yes it is possibile. If you use softdevice you will have to use RTC1 instance because RTC0 is used by softdevice.

[liu]

hello, chocol8, Thanks for your reply. Now i use

err_code = app_timer_create(&m_sleep_10s_timer_id,
APP_TIMER_MODE_REPEATED, sleep_10s_timeout_handler); uint32_t err_code2 = app_timer_start(m_sleep_10s_timer_id, SLEEP_10S_TEMP_INTERVAL, NULL);

in lowe power mode with power_manage(). But the current is vary from 10uA to 70uA, now rtc can wake NRF51822 every 10s. I donn't know why the current cost is so high and vary. Thanks.

[Chocol8]

This might be caused by any of the initialized peripherals e.g. UART, SPI, TWI. By the way do you use custom board or a DK from Nordic semiconductors? On a custom board there mught be DC/DC converters or some leakage.

[liu]

hello, chocol8. I use a custom board.I don't use uart,spi,twi ect, and i set pins not used to output and high. I used the chip in DC/DC converter mode. Otherwise, i used the button battery to support the voltage.

[Chocol8]

You should check the DC/DC current draws is specification. Moreover, if you have any Nordic semiconductors board you can load the code of yours there and check if the current is the same. If it is not equeal your custom board has hardware issues if it is the same then it is probably firmware issue.