To Armв® Cortex(t... - Embedded Systems: Introduction

Another is an , which acts like a thermometer, translating the "heat" of the room into a number the Watchman can understand.

Imagine a modern high-security greenhouse that protects a rare, temperature-sensitive flower. Inside this greenhouse sits the "Watchman"—an . Embedded systems: introduction to ARMВ® Cortex(T...

Most of the time, the Watchman is in a "Low Power Mode," dozing lightly to save energy (essential if he’s running on a battery). Suddenly, someone forces the greenhouse door open.In a normal computer, the CPU might be too busy to notice. But the Cortex-M has a Nested Vectored Interrupt Controller (NVIC) . This is like a red phone on the desk that rings instantly. The Watchman drops everything, jumps to the "Door Emergency" page of his manual, sounds the alarm, and then returns exactly to where he left off. Another is an , which acts like a

The Watchman is connected to the room through "wires" called GPIO pins . One wire is a Digital Input connected to a door sensor. Most of the time, the Watchman is in

Sometimes, the Watchman needs to move a huge pile of logs (data) from the thermometer to a storage logbook. If he did this himself, he couldn't watch the door. So, he uses his assistant, the Direct Memory Access (DMA) controller. He tells the DMA, "Move these 100 readings to memory and let me know when you're done." The Watchman stays focused on the big picture while the data moves in the background.

The ARM Cortex-M isn't the fastest brain in the world, but it is the most deterministic . In the world of embedded systems, it’s not about how much you can do—it’s about doing the right thing at the exact right microsecond, every single time, without ever taking a break.