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Tag Archives: Mutex
Embedded System Conference – India
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)
- Navigating Memory in C++: A Guide to Using std::uintptr_t for Address Handling - February 22, 2024
- Embedded Expertise: Beyond Fixed-Size Integers; Exploring Fast and Least Types - January 15, 2024
- Disassembling a Cortex-M raw binary file with Ghidra - December 20, 2022
This year I have honour of being invited to present at the Embedded Systems Conference in Bengaluru (Bangalore), India. Based on previous visits these classes are very well attended and always generate a lot of post-class discussions.
This year I’ve extended my previous 1/2 day class to a full day titled “Programming in C for the ARM Cortex-M Microcontroller”. Having a full day allows me to delve in too much greater detail. The class is broken down in to four subsections:
Cortex-M Architecture
C […]
Embedded Systems Conference – Silicon Valley
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)
- Navigating Memory in C++: A Guide to Using std::uintptr_t for Address Handling - February 22, 2024
- Embedded Expertise: Beyond Fixed-Size Integers; Exploring Fast and Least Types - January 15, 2024
- Disassembling a Cortex-M raw binary file with Ghidra - December 20, 2022
As I’m sure you’re well aware, the ash cloud from the Eyjafjallajokull volcano (which began erupting in mid-March) pretty much brought much of European airspace to a standstill over last weekend and into this week. Now that UK airspace has been reopened, it appears I can resume plans for my visit to the Embedded Systems Conference in San Jose next week.
The sessions I’m directly involved with are:
Examining ARM’s Cortex Microcontroller Software Interface Standard – CMSIS
Date/Time: Tuesday […]
Mutex vs. Semaphores – Part 3 (final part): Mutual Exclusion Problems
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)
- Navigating Memory in C++: A Guide to Using std::uintptr_t for Address Handling - February 22, 2024
- Embedded Expertise: Beyond Fixed-Size Integers; Exploring Fast and Least Types - January 15, 2024
- Disassembling a Cortex-M raw binary file with Ghidra - December 20, 2022
As hopefully you can see from the previous posting, the mutex is a significantly safer mechanism to use for implementing mutual exclusion around shared resources. Nevertheless, there are still a couple of problems that use of the mutex (in preference to the semaphore) will not solve. These are:
Circular deadlock
Non-cooperation
Circular Deadlock
Circular deadlock, often referred to as the “deadly embrace” problem is a condition where two or more tasks develop a circular dependency of mutual exclusion. Simply put, one task is blocked […]
Posted in RTOS
Tagged Deadlock, Deadly Embrace, Monitor, Mutex, Priority Ceiling Protocol, RTOS
14 Comments
Mutex vs. Semaphores – Part 2: The Mutex
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)
- Navigating Memory in C++: A Guide to Using std::uintptr_t for Address Handling - February 22, 2024
- Embedded Expertise: Beyond Fixed-Size Integers; Exploring Fast and Least Types - January 15, 2024
- Disassembling a Cortex-M raw binary file with Ghidra - December 20, 2022
In Part 1 of this series we looked at the history of the binary and counting semaphore, and then went on to discuss some of the associated problem areas. In this posting I aim to show how a different RTOS construct, the mutex, may overcome some, if not all, of these weaknesses.
To address the problems associated with semaphore, a new concept was developed during the late 1980’s. I have struggled to find it’s first clear definition, but the major use […]
Mutex vs. Semaphores – Part 1: Semaphores
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)
- Navigating Memory in C++: A Guide to Using std::uintptr_t for Address Handling - February 22, 2024
- Embedded Expertise: Beyond Fixed-Size Integers; Exploring Fast and Least Types - January 15, 2024
- Disassembling a Cortex-M raw binary file with Ghidra - December 20, 2022
It never ceases to amaze me how often I see postings in newsgroups, etc. asking the difference between a semaphore and a mutex. Probably what baffles me more is that over 90% of the time the responses given are either incorrect or missing the key differences. The most often quoted response is that of the “The Toilet Example (c) Copyright 2005, Niclas Winquist” . This summarises the differences as:
A mutex is really a semaphore with value 1
No, no and no […]