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Introduction
122
SLAU723A – October 2017 – Revised October 2018
Copyright © 2017–2018, Texas Instruments Incorporated
Cortex-M4 Peripherals
2.1
Introduction
This chapter describes the following peripherals:
•
SysTick
Provides a simple, 24-bit clear-on-write, decrementing, wrap-on-zero counter with a flexible control
mechanism.
•
Nested Vectored Interrupt Controller (NVIC)
–
Facilitates low-latency exception and interrupt handling
–
Controls power management
–
Implements system control registers
•
System Control Block (SCB)
Provides system implementation information and system control, including configuration, control, and
reporting of system exceptions.
•
Memory Protection Unit (MPU)
Supports the standard Armv7 Protected Memory System Architecture (PMSA) model. The MPU
provides full support for protection regions, overlapping protection regions, access permissions, and
exporting memory attributes to the system.
•
Floating-Point Unit (FPU)
Fully supports single-precision add, subtract, multiply, divide, multiply and accumulate, and square root
operations. It also provides conversions between fixed-point and floating-point data formats, and
floating-point constant instructions.
shows the address map of the Private Peripheral Bus (PPB). Some peripheral register regions
are split into two address regions, as indicated by two addresses listed.
Table 2-1. Core Peripheral Register Regions
Address
Core Peripheral
Description
0xE000.E010 to 0xE000.E01F
System Timer
0xE000.E100 to 0xE000.E4EF
0xE000.EF00 to 0xE000.EF03
Nested Vectored Interrupt Controller
0xE000.E008-0xE000.E00F
0xE000.ED00 to 0xE000.ED3F
System Control Block
0xE000.ED90 to 0xE000.EDB8
Memory Protection Unit
0xE000.EF30 to 0xE000.EF44
Floating Point Unit
2.2
Functional Description
This chapter provides information on the MSP432E4 implementation of the Cortex-M4 processor
peripherals: SysTick, NVIC, SCB, MPU, FPU.
2.2.1 System Timer (SysTick)
Cortex-M4 includes an integrated system timer, SysTick, which provides a simple, 24-bit clear-on-write,
decrementing, wrap-on-zero counter with a flexible control mechanism. The counter can be used in
several different ways, for example as:
•
An RTOS tick timer that fires at a programmable rate (for example, 100 Hz) and invokes a SysTick
routine.
•
A high-speed alarm timer using the system clock.
•
A variable rate alarm or signal timer—the duration is range-dependent on the reference clock used
and the dynamic range of the counter.
•
A simple counter used to measure time to completion and time used.
•
An internal clock source control based on missing/meeting durations. The COUNT bit in the STCTRL
control and status register can be used to determine if an action completed within a set duration, as