Key facts
- Brand
- STMicroelectronics
- Model
- AN3129
- Industry
- Industrial
- Documents
- 2
- Languages
- EN
- Last added
- 2012-08-06
Start here
STMicroelectronics AN3129 Real-time Performance Using FIQ Interrupt Handling in SPEAr MPUs Application Note
This document provides software developers with information on utilizing the Fast Interrupt Request (FIQ) mechanism within the Linux kernel on the SPEAr family of embedded MPUs. It details the interrupt logic, hardware mechanisms, and software requirements necessary to implement FIQ handlers effectively.
The note covers the specific limitations of using FIQs in a Linux environment, such as restrictions on API usage and memory access. Furthermore, it describes a latency measurement module included in the STLinux SPEAr BSP release kernel code, which allows developers to measure IRQ and FIQ handling latencies.
STMicroelectronics AN3129 specifications
| Kernel version used for measurements | Linux kernel version 2.6.27 |
|---|---|
| CPU frequency | ARM core running @333 MHz |
| RAM capacity and speed | 128 MB DDR2 running @333 MHz |
| Flash memory capacity | 8 MB NOR |
| Timer interval | 1 millisecond |
| Timer tick interval | 1/48 microsecond |
| Latency measurement range | 0 to 200 microseconds |
All STMicroelectronics AN3129 documents by type
How to use the product for one specific task, with worked examples.
Questions answered in these manuals
What is the maximum range of interrupt latency measured by the module?
The frequency counter captures a range from 0 to 9600 ticks, which corresponds to 0 to 200 microseconds.
What CPU speed was used in the performance measurements?
The ARM core running at 333 MHz was used for the performance measurements.
What is the maximum latency range measured by the module?
The frequency counter captures latency from 0 to 9600 ticks, which corresponds to a range of 0 to 200 microseconds.
Can Linux kernel APIs be used inside an FIQ handler?
No, kernel mode APIs and device driver framework cannot be used inside the FIQ handler because they may rely on timers or spinlocks.