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

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.

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...

The Watchman is connected to the room through "wires" called GPIO pins . One wire is a Digital Input connected to a door sensor. Sometimes, the Watchman needs to move a huge

The Watchman is incredibly disciplined. He doesn’t spend his time browsing the web or playing games like a "Desktop PC" manager would. Instead, he sits at a small desk with a set of very specific instructions (the Code ) and a tiny bit of scratchpad paper ( RAM ). He is designed to do one thing perfectly: keep that flower alive. He tells the DMA, "Move these 100 readings

A third wire is a signal that controls a heater. He doesn't just turn the heater "on" or "off"; he "pulses" it rapidly to keep the temperature perfectly steady, like a dimmer switch.