NRF51802-QFAA-R datasheet(28/85 Pages) NORDIC

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nRF51802 Product Specification v1.2

4.2

Timer/counters (TIMER)

The timer/counter runs on the high-frequency clock source (HFCLK) and includes a 4 bit (1/2X) prescaler that

can divide the HFCLK.

The TIMER will start requesting the 1 MHz mode of the HFCLK for values of the prescaler that gives fTIMER less

or equal to 1 MHz. If the timer module is the only one requesting the HFCLK, the system will automatically

switch to using the 1 MHz mode resulting in a decrease in the current consumption. See the parameters

I1v2XO16,1M, I1v2XO32,1M, I1v2RC16,1M in Table 30 on page 43 and ITIMER0/1/2,1M in Table 50 on page 57.

The task/event and interrupt features make it possible to use the PPI system for timing and counting tasks

between any system peripheral including any GPIO of the device. The PPI system also enables the TIMER

task/event features to generate periodic output and PWM signals to any GPIO. The number of input/outputs

used at the same time is limited by the number of GPIOTE channels.

Table 10 Timer/counter properties

4.3

Real Time Counter (RTC)

The Real Time Counter (RTC) module provides a generic, low power timer on the low-frequency clock source

(LFCLK). The RTC features a 24 bit COUNTER, 12 bit (1/X) prescaler, capture/compare registers, and a tick

event generator for low power, tickless RTOS implementation.

Table 11 RTC properties

4.4

AES Electronic Codebook Mode Encryption (ECB)

The ECB encryption block supports 128 bit AES block encryption. It can be used for a range of cryptographic

functions like hash generation, digital signatures, and keystream generation for data encryption/decryption.

ECB encryption uses EasyDMA to access system RAM for in-place operations on cleartext and ciphertext

during encryption.

Instance

Bit-width

Capture/Compare registers

TIMER0

8/16/24/32

TIMER1

8/16

TIMER2

8/16

Instance

Capture/Compare registers

RTC0

RTC1

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