M054LAN Datasheet, PDF (21/64 Pages) Nuvotem Talema – ARM Cortex™-M0 32-BIT MICROCONTROLLER

64M052/M054 Data Sheet
AVDD
AVSS
NuMicro-M051 Power Architecture
12-bit
SAR-ADC
Low Voltage
Reset
Brown Out Detector
FLASH
PLL
Digital Logic
(Timer/UART/I2C/SPI…)
IRC
22.1184MHz
& 10KHz Osc.
POR25
POR50
2.5V
5V to 2.5V
LDO
IO cell
LDO_CAP
10uF
P0~P4
Figure 6–2 NuMicro M051^™ Series Power Architecture Diagram
6.2.4 System Timer (SysTick)
The Cortex-M0 includes an integrated system timer, SysTick. SysTick provides a simple, 24-bit
clear-on-write, decrementing, wrap-on-zero counter with a flexible control mechanism. The
counter can be used as a Real Time Operating System (RTOS) tick timer or as a simple counter.
When system timer is enabled, it will count down from the value in the SysTick Current Value
Register (SYST_CVR) to zero, and reload (wrap) to the value in the SysTick Reload Value
Register (SYST_RVR) on the next clock edge, then decrement on subsequent clocks. When the
counter transitions to zero, the COUNTFLAG status bit is set. The COUNTFLAG bit clears on
reads.
The SYST_CVR value is UNKNOWN on reset. Software should write to the register to clear it to
zero before enabling the feature. This ensures the timer will count from the SYST_RVR value
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Publication Release Date: Mar 15, 2011
Revision V1.0