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When writing firmware for an embedded system, immunity-aware programming refers to programming techniques which improve the tolerance of transient errors in the program counter or other modules of a program that would otherwise lead to failure. Transient errors are typically caused by single event upsets, insufficient power, or by strong electromagnetic signals transmitted by some other "source" device. Immunity-aware programming is an example of defensive programming and EMC-aware programming. Although most of these techniques apply to the software in the "victim" device to make it more reliable, a few of these techniques apply to software in the "source" device to make it emit less unwanted noise. ==Task and objectives== Microcontrollers' firmware can inexpensively improve the electromagnetic compatibility of an embedded system. Embedded systems firmware is usually not considered to be a source of radio frequency interference. Radio emissions are often caused by harmonic frequencies of the system clock and switching currents. The pulses on these wires can have fast rise and fall times, causing their wires to act as radio transmitters. This effect is increased by badly-designed printed circuit boards. These effects are reduced by using microcontroller output drivers with slower rise times, or by turning off system components. The microcontroller is easy to control. It is also susceptible to faults from radio frequency interference. Therefore, making the microcontroller's software resist such errors can cheaply improve the system's tolerance for electromagnetic interference by reducing the need for hardware alterations. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Immunity-aware programming」の詳細全文を読む スポンサード リンク
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