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Category Archives: CMSIS
CMake Part 4 – Windows 10 Host
Associate Instructor at Feabhas Ltd
An independent IT trainer Martin has over 40 years academic and commercial experience in open systems software engineering. He has worked with a range of technologies from real time process controllers, through compilers, to large scale parallel processing systems; and across multiple sectors including industrial systems, semi-conductor manufacturing, telecomms, banking, MoD, and government.
Latest posts by Martin Bond (see all)
- CMake Presets - August 1, 2023
- C++20 Coroutine Iterators - September 23, 2021
- C++20 Coroutines - September 16, 2021
Introduction
In previous blog posts in this series (Part 1, Part 2 and Part 3), I looked at using CMake on a Linux host to configure a build to cross compile to target hardware such as the STM32F4 Series.
In this post, we’ll work with the GNU Arm Embedded Toolchain on a Windows 10 Host.
The first part of this blog discusses running the Windows hosted versions of CMake, GNU Arm Embedded Toolchain and GNU Make. An alternative approach, briefly discussed at the […]
Posted in ARM, Build-systems, C/C++ Programming, CMSIS, Cortex, Toolchain
Tagged CMake, Cross Compiler, Windows 10
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CMake Part 3 – Source File Organisation
Associate Instructor at Feabhas Ltd
An independent IT trainer Martin has over 40 years academic and commercial experience in open systems software engineering. He has worked with a range of technologies from real time process controllers, through compilers, to large scale parallel processing systems; and across multiple sectors including industrial systems, semi-conductor manufacturing, telecomms, banking, MoD, and government.
Latest posts by Martin Bond (see all)
- CMake Presets - August 1, 2023
- C++20 Coroutine Iterators - September 23, 2021
- C++20 Coroutines - September 16, 2021
Introduction
In previous blog posts in this series (Part 1 and Part 2), I looked at using CMake to configure a build for a cross compilation to target hardware such as the STM32F4 Series. In this blog post I will look at how to configure project source code, identify subsystems and use CMake to manage the build for each subsystem.
In our training courses, we have identified two shared subsystems: the bare metal code used to initialise the C/C++ run time system […]
Posted in ARM, Build-systems, C/C++ Programming, CMSIS, Cortex, Toolchain
Tagged CMake, Cross Compiler
3 Comments
Introduction to the ARM® Cortex®-M7 Cache – Part 3 Optimising software to use cache
Director at Feabhas Limited
Co-Founder and Director of Feabhas since 1995.
Niall has been designing and programming embedded systems for over 30 years. He has worked in different sectors, including aerospace, telecomms, government and banking.
His current interest lie in IoT Security and Agile for Embedded Systems.
Niall has been designing and programming embedded systems for over 30 years. He has worked in different sectors, including aerospace, telecomms, government and banking.
His current interest lie in IoT Security and Agile for Embedded Systems.
Latest posts by Niall Cooling (see all)
- Disassembling a Cortex-M raw binary file with Ghidra - December 20, 2022
- Using final in C++ to improve performance - November 14, 2022
- Understanding Arm Cortex-M Intel-Hex (ihex) files - October 12, 2022
Part 1 Cache Basics
Part 2 Cache Replacement Policy
Caches – Why do we miss?
Cold Start
As stated, both data and instruction caches are required to be invalidated on system start. Therefore, the first load of any object (code or data) cannot be in cache (thus the cold start condition).
One available technique to help with cold-start conditions is the ability to pre-load data into the cache. The ARMv7-M instruction set adds the Preload Data (PLD) instruction. The PLD instruction signals to the memory […]
Introduction to the ARM® Cortex®-M7 Cache – Part 2 Cache Replacement Policy
Director at Feabhas Limited
Co-Founder and Director of Feabhas since 1995.
Niall has been designing and programming embedded systems for over 30 years. He has worked in different sectors, including aerospace, telecomms, government and banking.
His current interest lie in IoT Security and Agile for Embedded Systems.
Niall has been designing and programming embedded systems for over 30 years. He has worked in different sectors, including aerospace, telecomms, government and banking.
His current interest lie in IoT Security and Agile for Embedded Systems.
Latest posts by Niall Cooling (see all)
- Disassembling a Cortex-M raw binary file with Ghidra - December 20, 2022
- Using final in C++ to improve performance - November 14, 2022
- Understanding Arm Cortex-M Intel-Hex (ihex) files - October 12, 2022
Part 1 Cache Basics
Instruction Cache Replacement Policy
Starting with the simpler instruction cache case; when we encounter a cache miss the normal policy is to evict the current cache line and replace it with the new cache line. This is known as a read-allocate policy and is the default on all instruction caches.
Cold start (first read)
It should also be noted that on system power-up the initial state of the cache is unknown. On the ARMv7-M all caches are disabled at reset. […]
Introduction to the ARM® Cortex®-M7 Cache – Part 1 Cache Basics
Director at Feabhas Limited
Co-Founder and Director of Feabhas since 1995.
Niall has been designing and programming embedded systems for over 30 years. He has worked in different sectors, including aerospace, telecomms, government and banking.
His current interest lie in IoT Security and Agile for Embedded Systems.
Niall has been designing and programming embedded systems for over 30 years. He has worked in different sectors, including aerospace, telecomms, government and banking.
His current interest lie in IoT Security and Agile for Embedded Systems.
Latest posts by Niall Cooling (see all)
- Disassembling a Cortex-M raw binary file with Ghidra - December 20, 2022
- Using final in C++ to improve performance - November 14, 2022
- Understanding Arm Cortex-M Intel-Hex (ihex) files - October 12, 2022
For many years, the majority of smaller microprocessor-based systems have typically not used caches. With the launch of the ARMv7 architectures, caches were supported in the ARMv7-A family (e.g. Cortex-A8, etc.) but not supported in the core design of the ARMv7-M micro-controllers such as the Cortex-M3 and Cortex-M4. However, when the Cortex-M7 was announced, it broke that mould by offering cache support for the smaller embedded micro-controller.
This series is broken down in three parts:
Basic principles of cache
Cache replacement policies
Optimising software […]
Posted in ARM, CMSIS, Cortex, Design Issues
Tagged cache, Cortex-M, cortex-m7, modified harvard, TCM
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Side effects and sequence points; why volatile matters
Director at Feabhas Limited
Co-Founder and Director of Feabhas since 1995.
Niall has been designing and programming embedded systems for over 30 years. He has worked in different sectors, including aerospace, telecomms, government and banking.
His current interest lie in IoT Security and Agile for Embedded Systems.
Niall has been designing and programming embedded systems for over 30 years. He has worked in different sectors, including aerospace, telecomms, government and banking.
His current interest lie in IoT Security and Agile for Embedded Systems.
Latest posts by Niall Cooling (see all)
- Disassembling a Cortex-M raw binary file with Ghidra - December 20, 2022
- Using final in C++ to improve performance - November 14, 2022
- Understanding Arm Cortex-M Intel-Hex (ihex) files - October 12, 2022
Introduction
Most embedded programmers, and indeed anyone who has attended a Feabhas programming course, is familiar with using the volatile directive when accessing registers. But it is not always obvious the ‘whys and wherefores’ of the use of volatile.
In this article, we explore why using volatile works, but more importantly, why it is needed in the first place.
Peripheral register access
If we start with a simple, fictitious, example. Suppose we have a peripheral with the following register layout:
register
width
offset
control
byte
0x00
configuration
byte
0x01
data
byte
0x02
status
byte
0x03
with a base address of […]
Posted in ARM, C/C++ Programming, CMSIS, Cortex
Tagged ARM, arm-gcc, sequence point, side effect, volatile
2 Comments
Peripheral register access using C Struct’s – part 1
Director at Feabhas Limited
Co-Founder and Director of Feabhas since 1995.
Niall has been designing and programming embedded systems for over 30 years. He has worked in different sectors, including aerospace, telecomms, government and banking.
His current interest lie in IoT Security and Agile for Embedded Systems.
Niall has been designing and programming embedded systems for over 30 years. He has worked in different sectors, including aerospace, telecomms, government and banking.
His current interest lie in IoT Security and Agile for Embedded Systems.
Latest posts by Niall Cooling (see all)
- Disassembling a Cortex-M raw binary file with Ghidra - December 20, 2022
- Using final in C++ to improve performance - November 14, 2022
- Understanding Arm Cortex-M Intel-Hex (ihex) files - October 12, 2022
When working with peripherals, we need to be able to read and write to the device’s internal registers. How we achieve this in C depends on whether we’re working with memory-mapped IO or port-mapped IO. Port-mapped IO typically requires compiler/language extensions, whereas memory-mapped IO can be accommodated with the standard C syntax.
Embedded “Hello, World!”
We all know the embedded equivalent of the “Hello, world!” program is flashing the LED, so true to form I’m going to use that as an example.
The […]
Updated: Developing a Generic Hard Fault handler for ARM Cortex-M3/Cortex-M4 using GCC
Director at Feabhas Limited
Co-Founder and Director of Feabhas since 1995.
Niall has been designing and programming embedded systems for over 30 years. He has worked in different sectors, including aerospace, telecomms, government and banking.
His current interest lie in IoT Security and Agile for Embedded Systems.
Niall has been designing and programming embedded systems for over 30 years. He has worked in different sectors, including aerospace, telecomms, government and banking.
His current interest lie in IoT Security and Agile for Embedded Systems.
Latest posts by Niall Cooling (see all)
- Disassembling a Cortex-M raw binary file with Ghidra - December 20, 2022
- Using final in C++ to improve performance - November 14, 2022
- Understanding Arm Cortex-M Intel-Hex (ihex) files - October 12, 2022
The original article was first posted back in 2013. Since posting I have been contacted many times regarding the article. One re-occuring question has been “How do I do this using GCC?”. So I thought it was about time I updated the article using GCC.
GNU Tools for ARM Embedded Processors
The original article used the Keil toolchain, here I am using arm-none-eabi-gcc. One of the major benefits of CMSIS is that almost all the code from the original posting will compile […]
Test Driven Development (TDD) with the mbed
Director at Feabhas Limited
Co-Founder and Director of Feabhas since 1995.
Niall has been designing and programming embedded systems for over 30 years. He has worked in different sectors, including aerospace, telecomms, government and banking.
His current interest lie in IoT Security and Agile for Embedded Systems.
Niall has been designing and programming embedded systems for over 30 years. He has worked in different sectors, including aerospace, telecomms, government and banking.
His current interest lie in IoT Security and Agile for Embedded Systems.
Latest posts by Niall Cooling (see all)
- Disassembling a Cortex-M raw binary file with Ghidra - December 20, 2022
- Using final in C++ to improve performance - November 14, 2022
- Understanding Arm Cortex-M Intel-Hex (ihex) files - October 12, 2022
One of the most useful fallout’s from the acceptance of Agile techniques is the use of Test-Driven-Development (TDD) and the growth of associated test frameworks, such as GoogleTest and CppUTest, etc.
I won’t get into the details of TDD here as they are well covered elsewhere (I recommend James Grenning’s book “Test Driven Development for Embedded C” for a good coverage of the subject area), but the principle is
Write a test
Develop enough code to compile and build (but will fail the test)
Write the application code […]
Posted in ARM, C/C++ Programming, CMSIS, Cortex, Testing
4 Comments
Rehosting ARMCC for the mbed with CMSIS-DAP
Director at Feabhas Limited
Co-Founder and Director of Feabhas since 1995.
Niall has been designing and programming embedded systems for over 30 years. He has worked in different sectors, including aerospace, telecomms, government and banking.
His current interest lie in IoT Security and Agile for Embedded Systems.
Niall has been designing and programming embedded systems for over 30 years. He has worked in different sectors, including aerospace, telecomms, government and banking.
His current interest lie in IoT Security and Agile for Embedded Systems.
Latest posts by Niall Cooling (see all)
- Disassembling a Cortex-M raw binary file with Ghidra - December 20, 2022
- Using final in C++ to improve performance - November 14, 2022
- Understanding Arm Cortex-M Intel-Hex (ihex) files - October 12, 2022
In this posting I will look at porting the C standard library output (e.g. puts / printf ) to use a UART rather than the default ARM/Keil semihosting.
In my last post, I looked at getting basic user I/O out from a native-mbed via UART0 to a terminal emulator (e.g. Tera Term). This was driven by the fact that, currently, neither printf (via semihosting) or ITM_SendChar do not function on the mbed. Unfortunately, my solution uses a propriety API, such as init_serial0 and putchar0, […]
Posted in ARM, C/C++ Programming, CMSIS, Cortex
3 Comments