Embedded controller

from Wikipedia, the free encyclopedia
This article or section needs to be revised. Details should be given on the talk page. Please help to improve it , and then remove this flag.

An embedded controller ( EC ) is a special microcontroller in notebooks that takes on various control tasks regardless of the operating system .

tasks

An embedded controller typically has the following tasks:

  • Reception of key press signals, both from the notebook keyboard and from other keys and switches (e.g. power key, lid switch)
  • Switching the actual computer system on and off
  • Charge control of the battery
  • Measurement of temperature
  • Control of fans and other coolers
  • Putting the actual computer system into a "sleep mode" ( standby ) and waking it up again (resume)
  • Control of any LEDs on the system

The embedded controller is always switched on when the power is supplied.

The actual computer system can often communicate with the embedded controller. One of the following forms of communication is often used for this:

software

The embedded controller has its own RAM and almost always flash ROM on which the software to be executed is stored. This software is named differently depending on the manufacturer :

  • " Firmware ", "EC Firmware" or "Embedded Controller Firmware"
  • "EC BIOS " or "Embedded Controller BIOS"
  • "Microcontroller software"
  • "Keyboard BIOS", "Keyboard Controller BIOS" or "KBC BIOS"

In addition to updating the actual BIOS software, many BIOS updates also contain an update of the embedded controller firmware.

In cases where there is no separate firmware for the BIOS and the embedded controller, the embedded controller and the actual CPU probably have shared access to the only flash memory in the system. This shared access often also means the shared memory communication form .

Surname

Hence the name "Keyboard Controller BIOS" is that the Embedded Controller almost always the task of the keyboard control the notebook keyboard takes over. Historically, what used to be just the keyboard controller has developed into an embedded controller . Even today, when communicating with an ACPI Embedded Controller , the same path ( port 0x62 and port 0x66) is used as it used to be for communication with the keyboard controller.

System architectures

Frequently used microcontroller architectures for embedded controllers are:

Well-known embedded controller models

ergonomics

Even if the embedded controller is very "deep" in the system, it can still be important for the user because it controls the cooling . Notebooks (even with energy-saving technology) often produce so much waste heat that the controller decides to turn on the fan based on the temperature. The fan is not simply switched on, but "turned up" for a short time and then left at a lower speed until the temperature falls below the desired temperature. This can be very uncomfortable for ergonomic work , especially if it occurs regularly and the fan is clearly audible - especially in quiet rooms.

This can be remedied by changing the control: The fan is no longer "turned up" and the speed remains very low - at moderate temperatures. In this case, it is likely that the resulting air flow is no longer turbulent , but laminar and the fan is hardly audible. Often the cooling performance of such a modified system is almost as good as that of the original system. If it is not, however, a ventilation process takes longer until the temperature falls below the target temperature.

In order to implement such a modification, it is usually necessary to change the embedded controller firmware. Sometimes a change to the ACPI DSDT is sufficient (namely when the fan control is not carried out by the embedded controller, but by the system's ACPI interpreter ).

Web links