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Reducing Suspend Power of Embedded System by Hot Removing Memory Parts

IP.com Disclosure Number: IPCOM000204646D
Publication Date: 2011-Mar-08
Document File: 5 page(s) / 63K

Publishing Venue

The IP.com Prior Art Database

Abstract

Big amount of system volatile memory is more and more popular in the embedded system, such as smart-book or net-book. Big amount of memory will consume a lot of power even when it is in self-refreshing mode during system suspend. The proposed method saves memory power consumption by hot-removing and power off volatile memory parts during system is in suspend mode.

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Reducing Suspend Power of Embedded System by Hot Removing Memory Parts

Abstract

Big amount of system volatile memory is more and more popular in the embedded system, such as smart-book or net-book. Big amount of memory will consume a lot of power even when it is in self-refreshing mode during system suspend. The proposed method saves memory power consumption by hot-removing and power off volatile memory parts during system is in suspend mode.

Body

Background

Embedded computing system, comprising: embedded CPU, system volatile memory, power control unit and peripherals.

The embedded CPU supports normal mode, sleep (suspending) mode. When the embedded system is idle, no tasks are running and no input/output is running. The CPU could enter suspending mode and wait for resume events.

Power control unit could control the power source of different modules, including peripherals and volatile memory chips.

Peripherals could be power off when system enters suspending mode.

In embedded system, system volatile memory could operate in various power modes, such as normal mode, self-refreshing mode and power down mode. When embedded system enters suspending mode, system volatile memory could enter self-refreshing mode or power down mode.

However, in self-refreshing mode, system volatile memory still consumes power. And the power consumption of self-refreshing volatile memory is big part of whole suspending system. For example, a typical 256MB DDR2 chip often consumes 5mA or 9mW (5mA*1.8V) in self-refresh mode.

Big amount of system volatile memory is more and more popular in the embedded system, such as smart-book or net-book, 1~2GB system RAM is normal configuration. That means there will be many chips of system RAM. During self-refreshing, 2GB RAM size means 8 256MB DDR2 chips and 72mW. If half parts are cut, 36mW is reduced. That means battery life is extended by several hours.

Solution Details

1.                  In the embedded system, the power control unit could control the power source of system volatile memory chips independently. That means parts of system volatile memory chips are power off when others are power on.

2.                  Divide system volatile memory into several parts logically which can be hot adding to and hot removing from system memory pool. One part, kernel part, is for OS kernel and desktop management program, and other parts, user part, are for user applications.

3.                  System volatile memory logic part is smaller or equal to the capacity of system volatile memory chip. That means power control unit could control the power of one or more logic parts independently.

4.                  Kernel part is used to store OS kernel and desktop management program, which will be initialized during system bring-up. It enters self-refreshing mode when system suspends. When system resumes, OS kernel and desktop management program get active immediately. This will help to improve user experience.

5.                  User part is used for all user applications, which will be initialized later for user applicati...