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ac6 >> ac6-training >> Processors >> ARM Cores >> Cortex-R7 implementation Download Catalog Download as PDF Write us Printable version

RR2 Cortex-R7 implementation

This course covers the Cortex-R7MP ARM cores

  • This course is split into 3 important parts:
    • Cortex-R7 architecture
    • Cortex-R7 software implementation and debug
    • Cortex-R7 hardware implementation.
  • Interaction between level 1 caches, TCM and main memory is studied through sequences.
  • The course explains how to assign access permissions and attributes to regions by using the MPU.
  • The exception mechanism is detailed, indicating how the GIC can contribute to reduce interrupt latency.
  • Sequences involving memory, cache and external masters are used to explain the benefits of the ACP port.
  • The course also details the hardware implementation and provides some guidelines to design a SoC based on a Cortex-R7.
  • An overview of the Coresight specification is provided prior to describing the debug related units.
A more detailed course description is available on request at
Prerequisites and related courses
  • Basic knowledge of the ARM architecture.
  • Assembly-level programming notions
Course material
  • Printed training material is given to attendees during training.
  • Precise and easy to use, it can be used as a reference afterwards.

First day
ARM Basics
  • States and modes
  • Benefit of register banking
  • Exception mechanism
  • Instruction sets
  • Purpose of CP15
Introduction to Cortex-R7
  • Block diagram
  • Slave and master AXI ports
  • Highlighting the new features with regard to Cortex-R4/R5
  • ARMv7-R architecture
  • Operating modes
  • Supported instruction sets
  • Program Status register
  • Exceptions
  • System control coprocessor
  • Configurable options
  • Implementing two CPUs
    • Cache coherency using the SCU
    • Accelerated Coherency Port
    • Redundant CPU vs Dual CPU
    • Split/Lock configuration
Cache Coherency
  • Hardware coherency
    • SCU implementation
    • The MESI and MOESI protocols
  • ACP interface, providing hardware coherency for DMA accesses
  • PMU related events
Instruction Pipeline
  • Prefetch unit
  • Studying how instructions are processed step by step
  • Instruction cycle timings and interlock behavior
  • Dynamic branch prediction mechanism: global history buffer
  • Guidelines for optimal performance
  • Data Processing Unit
  • Multiple issuing
  • Global History Buffer
  • Return stack
  • Instruction Memory Barrier
  • Prefetch queue flush
  • PMU related events
Memory Types
  • Memory types, restriction regarding load / store multiple
  • Device and normal memory ordering
  • Memory type access restrictions
  • Access order
  • Memory barriers, self-modifying code
Memory Protection Unit
  • Memory protection overview, ARM v7 PMSA
  • Default memory map
  • Cortex-R7 MPU and bus faults
  • Fault status and address registers
  • Region overview, memory type and access control, sub-regions
  • Region overlapping
  • Setting up the MPU
Second day
OS support – Synchronization Overview
  • Inter-Processor Interrupts
  • Cluster ID
  • Exclusive access monitor, implementing Boolean semaphores
  • Global monitor
  • Spin-lock implementation
  • Using events
  • Indicating the effect of Multi Core on debug interfaces
Exception management
  • Low Interrupt Latency: abandoning load / store instructions in progress
  • Configuring the state in which exceptions are handled: endian mode, instruction set
  • Nested interrupt management
  • Configuring the FIQ as non-maskable
  • Abort exception, fault handling
  • Determining the cause of the fault through CP15 status registers
  • Precise vs imprecise faults
Generic Interrupt Controller (GICv1)
  • Integration in a SoC based on Cortex-R7
  • Cortex-R7 exception management
  • Interrupt virtualization
  • Integrated timer and watchdog unit in MPCore
  • Interrupt groups: SGI, PPI, SPI, LSPI
  • Legacy mode management for IRQ and FIQ
  • Prioritization of the interrupt sources
  • Distribution of the interrupts to the Cortex-R7 cores
  • Detailing the interrupt sequence
  • Spurious interrupt
Level 1 Memory System
  • Cache basics: organization, replacement algorithm, write policies
  • Cache organization
  • Write with allocate policy
  • Tag RAM and Data RAM organization
  • Debugging when caches are active
  • Parity / ECC protection, handling cache parity / ECC errors
  • Understanding transient cache line load / store: linefill buffers, eviction buffer
  • Cache maintenance operations
  • Tightly Coupled Memories, address decoding
  • ITCM and DTCM configuration
  • Accessing the TCMs from the AXI slave interface
  • ECC protection, TCM internal error detection and correction
  • Preloading TCMs with ECC
  • Using TCMs from reset
  • Store buffer, merging data
  • L1 caches software read for debug purposes
  • PMU related events
Third day
Performance Monitoring Unit
  • Event counting
  • Selecting the event to be counted for the 3 counters
  • Related interrupts
  • Debugging a multi-core system with the assistance of the PMU
  • Use of the event bus and counters
AXI Protocol
  • Topology: direct connection, multi-master, multi-layer
  • Separate address/control and data phases
  • AXI channels, channel handshake
  • Support for unaligned data transfers
  • Transaction ordering, out of order transaction completion
  • Read and write burst timing diagrams
  • ECC management
  • Write merging example
  • Sideband signals
APB – Advance Peripheral Bus
  • Second-level address decoding
  • Pinout
  • Read timing diagram
  • Write timing diagram
  • APB3.0 new features
Cortex-R7 Level-2 Interface
  • AXI Master interfaces
    • Main interface attributes
    • Optional second master interface
    • Identifying virtual masters
  • AXI Peripheral interface
    • Peripheral interfaces port attributes
    • Identifiers for AXI peripheral port accesses
  • Optional ACP port
  • AXI slave interface
    • Slave interface attributes
    • Enabling or disabling AXI slave accesses
  • Slave APB debug interface
Hardware Implementation
  • Clock domains
  • Reset domains, power-on reset and debug reset
  • Power control, dynamic power management
  • Separate debug and core power domains
  • Clock gating
  • Maintaining caches and TCM powered while turning off the pipeline: dormant mode
  • Power mode interaction with ACP
  • Wait For Interrupt architecture
  • Debugging the processor while powered down
Low Power Modes
  • Voltage domains
  • Run mode, standby mode, dormant mode
  • Studying the sequence required to enter and exit dormant mode
  • Communication to the power management controller
  • Standby and wait for event signals, implementation in a multi-core system
Coresight Debug Units Overview
  • Benefits of CoreSight
  • Invasive debug, non-invasive debug
  • APBv3 debug interface
  • Connection to the Debug Access Port
  • Debug facilities offered by Cortex-R7
  • Process related breakpoint and watchpoint
  • Program counter sampling
  • Event catching
  • Debug Communication Channel
  • ETM interface, connection to funnel
  • Debugging while the processor is in shutdown or dormant mode
  • Debug registers description
  • Miscellaneous debug signals
  • Cross-Trigger Interface, debugging a multi-core SoC
  • Debugging systems with energy management capabilities