1. ARM Embedded Systems

2. Agenda RISC Design Philosophy ARM Design Philosophy
Embedded System Hardware
Embedded System Software

3. RISC Design Philosophy
Instructions
A fixed size: 32-bit
Executes in a single cycle
Pipelines
Registers
A large general-purpose register set
Load-store architecture

4. ARM Design Philosophy Variable cycle execution for some instructions
LDM/STM, SWP
Inline barrel shifter leading to more complex instructions
Thumb 16-bit instruction set
Conditional execution
Enhanced DSP instructions

5. Embedded System Hardware

6. ARM Processor Controls the embedded device
ARM Core + (MMU/MPU) + (Caches)

7. Controllers Memory Controller Interrupt Controller
Standard Interrupt Controller
Vector Interrupt Controller (VIC)

8. Peripherals
Provide all the input-output capability external to the chip
Memory mapped
the programming interface is a set of memory-addressed registers
Examples
Serial communication devices
wireless device
Real-Time Clock

9. Bus Communicates between different parts of the device
AMBA (Advanced Microcontroller Bus Architecture)
ASB ( ARM System Bus)
APB (ARM Peripheral Bus)
AHB (ARM High Performance Bus)
Multi-layer AHB
AHB-lite

10. ARM Embedded Software Initialization Code (Boot Code) Device Drivers
Operating System
Application

11. Initialization Code Configures the hardware to known state
Configures the memory controller and processor caches
initializes some devices
Phases
Initial Hardware Configuration
Diagnostics
Booting

12. Device Driver
provides a standard interface to peripherals

13. Operating System
Provides a common programming environment for the use of hardware resources and infrastructure
ARM processors support over 50 operating systems.
2 main categories
Real-time Operating System (RTOS)
Platform Operating System

14. Real-Time Operating Systems
Provide guaranteed response times to events
Hard real-time application
Requires a guaranteed response to work
Soft real-time application
Requires a good response time
Ex) VxWorks, pSOS, ThreadX, NucleausOS

15. Platform Operating Systems
Requires a MMU to manage large, non real-time applications
Ex) Linux, WinCE

16. Device Driver
provides a standard interface to peripherals

17. Applications < Networking Application > Home gateways
DSL modems for high-speed Internet communication
wireless communication
< Mass Storage devices >
Hard drives
Imaging products such as inkjet printers