UM10462 All information provided in this document is subject to legal disclaimers. © NXP B.V. 2016. All rights reserved.
User manual Rev. 5.5 — 21 December 2016 380 of 523
NXP Semiconductors
UM10462
Chapter 18: LPC11U3x/2x/1x System tick timer
Since the SysTick timer is a part of the Cortex-M0, it facilitates porting of software by
providing a standard timer that is available on Cortex-M0 based devices. The SysTick
timer can be used for:
• An RTOS tick timer which fires at a programmable rate (for example 100 Hz) and
invokes a SysTick routine.
• A high-speed alarm timer using the core clock.
• A simple counter. Software can use this to measure time to completion and time used.
• An internal clock source control based on missing/meeting durations. The
COUNTFLAG bit-field in the control and status register can be used to determine if an
action completed within a set duration, as part of a dynamic clock management
control loop.
Refer to the Cortex-M0 User Guide for details.
18.5 Register description
The systick timer registers are located on the ARM Cortex-M0 private peripheral bus (see
Figure 4
), and are part of the ARM Cortex-M0 core peripherals. For details, see
Section 24.5.4
.
[1] Reset Value reflects the data stored in used bits only. It does not include content of reserved bits.
18.5.1 System Timer Control and status register
The SYST_CSR register contains control information for the SysTick timer and provides a
status flag. This register is part of the ARM Cortex-M0 core system timer register block.
For a bit description of this register, see Section 24.5.4
.
This register determines the clock source for the system tick timer.
Table 345. Register overview: SysTick timer (base address 0xE000 E000)
Name Access Address
offset
Description Reset value
[1]
Reference
SYST_CSR R/W 0x010 System Timer Control and status register 0x000 0000 Table 346
SYST_RVR R/W 0x014 System Timer Reload value register 0 Table 347
SYST_CVR R/W 0x018 System Timer Current value register 0 Table 348
SYST_CALIB R/W 0x01C System Timer Calibration value register 0x4 Table 349
To Next Page
Loading...
Need help?
General
