Flow meter dynamic power management module Design (1)

Introduction

And other portable electronic products, hemodynamic parameters gauge to be compact and slim, durable, reliable performance, and standby time is long.

Therefore, a system designed to reduce power consumption and battery life of daunting challenges. Power management module is a very important part of the system, it includes battery charger, battery testing, CPU state transitions, LCD and keypad backlight control. This article from the hardware and software design two angles to achieve these features.

Large practice has proved that the system idle time total running time of a majority.

Power management is to reduce the system idle time of energy consumption, make energy efficient embedded systems to maximize the supply rate, thereby extending battery life. In order to extend battery life, in the hardware field, low-power circuit design methodology has been widely applied. However, the mere use of a low-power circuit still not enough, in system design, the use of "dynamic power management" concept, that is, the system is not in use by the component to close or enter low power mode (standby mode). In addition to a more efficient approach is to dynamically variable voltage DVS and dynamic variable frequency DFS, in run-time dynamic adjustment of the CPU frequency or voltage. So you can meet instantaneous performance, making the effective rate of energy supply.

1 system design

The entire instrument design uses S3C44B0 chip and uClinux OS.

S3C44B0 chip is industry application, lower power consumption, low cost of mid-range products. It provides five kinds of work status: NORMAL, SLOW, STOP and IDLE, SL_IDLE [1]. The system works in the NORMAL state, when a user without operating window larger than a certain threshold, you go to the IDLE state, the user presses enter False shutdown, then STOP State system power consumption is very low. For ease of administration, application layer on the power management State had a fine Division, the introduction of power management in six States: data collection status, functional status, readiness, rest State, IDLE status and STOP State. Among them, the IDLE status and STOP State and chip provides the same content, the application is responsible for the status of migration. The entire instrument power is the largest component is backlight (EL backlight and keyboard LED), LCD and sensor-driven, followed by CPU, power management state migration as shown in Figure 1.

Figure 1 system power management state migration

1.1 power management model

Figure 2 is a power management principle diagram, which consists of six modules: Vcore, Vio, Backup, Charge, Vdriver and Vlcd, they are part of the system.

Figure 2 system power management diagrams

Vcore-system kernel power supply voltage V 1.8; Vio is the system's i/o port power supply, power supply voltage for system Backup 3.3V; backup battery, battery voltage: 3 V; Charge the battery for charging circuit voltage of the battery; 3.6V Vdriver sensor power supply circuit, voltage ± 5 V; power for LCD module Vlcd, power supply voltage is 3 .3V and 200VCA.