OM13008,598 NXP Semiconductors, OM13008,598 Datasheet - Page 422

• Manufacturer Part Number: OM13008,598
• Description: BOARD LPC XPRESSO LPC122X
• Manufacturer: NXP Semiconductors
• Series: LPCXpressor

Specifications of OM13008,598

• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: 568-6642; OM13008

NXP Semiconductors
UM10441
User manual
25.5.4.5 SysTick usage hints and tips
Table 395. SYST_CALIB register bit assignments
If calibration information is not known, calculate the calibration value required from the
frequency of the processor clock or external clock.
The interrupt controller clock updates the SysTick counter.
Ensure software uses word accesses to access the SysTick registers.
If the SysTick counter reload and current value are undefined at reset, the correct
initialization sequence for the SysTick counter is:
Bits
[31]
[30]
[29:24]
[23:0]
1. Program reload value.
2. Clear current value.
3. Program Control and Status register.
Name
NOREF
SKEW
-
TENMS
All information provided in this document is subject to legal disclaimers.
Function
Reads as one. Indicates that no separate reference clock is provided.
Reads as one. Calibration value for the 10ms inexact timing is not known
because TENMS is not known. This can affect the suitability of SysTick
as a software real time clock.
Reserved.
Reads as zero. Indicates calibration value is not known.
Rev. 1.1 — 10 March 2011
Chapter 25: LPC122x Appendix ARM Cortex-M0
UM10441
© NXP B.V. 2011. All rights reserved.
422 of 442