WARNING!
Do not plug two or more meters together!
IMPORTANT
Don't plug in an appliance where the load
exceeds 16 Amp. Always ensure the plug of any appliance is fully
inserted into the meter outlet. If cleaning of the meter is required,
remove from mains power and wipe meter with a dry cloth.
KEYBOARD DEFINITION
1). SET: Set price with button UP.
2). MODE: Exchange display state.
3). UP: Set price combined with button SET.
GENERAL FEATURES
1).Display line power.
2).Display and memory accumulative total power quantity.
3).Display and memory total power charge of price.
THE DATA DISPLAY
Press MODE button the data displays as follows:
W →KWh →PRICE →COST/KWH
↑_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _↓
1). Plug in socket and power on, the meter will display real power.
2). Press MODE button once again and release, the meter will display accumulative KWh.
3). Press MODE button once again and release, the meter will display total power charge.
4). Press MODE button once again and release, the meter will display COST/KWH.
SETTING PRICE OF COST/KWH
1). Press SET button during display COST/KWH,the first digital COST/KWH flash, press UP button to set it.
2). Press SET button once again and release, the second digital COST/KWH flash, press UP button to set it.
3). Press SET button once again and release, the third COST/KWH flash, press UP button to set it.
4). Press SET button once again and release, the fourth COST/KWH flash, press UP button to set it.
5). Press SET button once again and release, the radix point COST/KWH flash, press UP button to set it.
DATA CLEAR
Press and hold MODE button for 5 seconds will clear KWH,PRICE and COST/KWH data.
Power Meter Plug Energy Monitor,Backlight Power Metering Socket,Blue Backlight Power Meter Socket,Multi-functional Backlight Power Meter Socket NINGBO COWELL ELECTRONICS & TECHNOLOGY CO., LTD , https://www.cowellsockets.com
Introduction to low-power design of smartphones
As smartphones become increasingly powerful, their energy consumption has also risen significantly. Extending the battery life and standby time of these devices is a major concern for users. With limited battery capacity, this article explores how advanced technologies can be used to optimize system design and reduce power loss in smartphones.
With the rapid development of the communication industry, mobile terminals have evolved from simple voice calling devices to multifunctional tools that support voice, data, images, music, and multimedia. There are two main types of mobile devices: feature phones and smartphones. Smartphones offer more advanced features compared to traditional phones, including an open operating system, scalable hardware and software, and support for third-party applications. Due to their powerful functions and user-friendly interface, smartphones are becoming increasingly popular and are expected to dominate the market in the future.
However, as portable devices, smartphones rely entirely on batteries for power. As their functionality grows, so does their power consumption. To address this, two solutions are commonly considered: increasing battery capacity or improving system design through advanced technology to reduce power loss.
Currently, most smartphones use lithium-ion batteries. Although their energy density has improved by nearly 30%, it still falls short of meeting the growing demands of modern smartphones. The potential for improvement in current lithium-ion materials is estimated at around 20%. Another promising alternative, fuel cell technology, could potentially extend talk time to over 13 hours and standby time to up to one month. However, this technology is still in the experimental phase and not yet commercially viable. Increasing battery size may also raise device costs.
Therefore, optimizing the overall smartphone design with advanced technologies is essential to reduce power loss and maximize battery life. Low-power design has now become a critical issue in smartphone development.
### 1. Smartphone Hardware System Architecture
This article discusses a dual-CPU architecture for smartphones, as shown in Figure 1.
The main processor runs an open operating system and controls the entire system. The digital baseband chip (DBB) handles tasks such as analog-to-digital conversion, digital signal encoding and decoding, and wireless modem timing control. The master and slave processors communicate via a serial port. The main processor uses a CMOS-based CPU chip with an ARM926EJ-S core, AMBA architecture, 16KB instruction and data cache, and an MMU. It includes an optimized MPEG4 hardware codec for real-time video conferencing, reducing the load on the ARM core. The main processor also contains an LCD controller, camera controller, SDRAM and SROM controllers, multiple GPIO ports, and an SD card interface, making it ideal for smartphone design.
In the smartphone’s hardware architecture, the wireless modem only requires additional peripheral circuits such as an audio chip, LCD, camera controller, microphone, speaker, power amplifier, and antenna to function as a complete traditional phone. The analog baseband (ABB) communicates with the audio codec to form a voice channel during calls.
The most power-hungry components in this system include the main processor, wireless modem, LCD and keyboard backlight, audio codec, and power amplifier. Reducing their power consumption is a key challenge in low-power design.
### 2. Low-Power Design
#### 2.1 Reduce CPU Supply Voltage and Frequency
In digital integrated circuit design, the static power consumption of CMOS circuits is very low and typically negligible compared to dynamic power. Dynamic power consumption is calculated using the formula:
$$ P_d = CTV^2f $$
Where:
- $ P_d $ is the dynamic power,
- $ C $ is the load capacitance,
- $ V $ is the supply voltage,
- $ f $ is the operating frequency.
From this equation, it's clear that power consumption increases linearly with frequency and quadratically with voltage. Therefore, to reduce power consumption while maintaining performance, the CPU should operate at the lowest possible voltage and frequency.
#### 2.2 Software Optimization
Software optimization plays a crucial role in improving efficiency and reducing power consumption. For example, reordering instructions can eliminate pipeline stalls caused by load, branch, or jump delays without affecting the program’s outcome. By minimizing the Hamming distance between successive instructions, the power consumption of the optimized code can be significantly reduced.
#### 2.3 Handling Floating Pins
Floating pins on CMOS devices must be carefully managed. If left unconnected, they can cause high-voltage breakdowns or random signal fluctuations, leading to unintended wakeups during sleep mode. Properly connecting unused inputs to a power rail or ground ensures stable operation.
#### 2.4 Buffer Selection
Buffers provide level shifting, increased drive capability, and data direction control. However, excessive drive currents can waste energy. It's important to ensure that the output current of the chip is sufficient to drive the next stage without unnecessary power loss.
#### 2.5 Power Supply Circuit
With a dual-CPU architecture, multiple power supplies are required. Linear regulators (LDOs) are simple but inefficient, while DC/DC converters offer higher efficiency and flexibility. Choosing the right power management solution helps reduce overall power consumption.
#### 2.6 LED Backlight Control
LCD and keyboard backlights consume significant power. Techniques such as resistor adjustment, PWM control, and brightness adjustment interfaces can effectively reduce their power usage.
#### 2.7 Wireless Modem Control
The wireless modem must remain active during sleep mode to handle incoming calls and network searches. A dedicated power management module allows it to enter and exit standby mode efficiently, reducing overall power draw.
#### 2.8 Software Optimization
Through careful configuration of registers and clock settings, the main CPU frequency can be optimized to balance performance and power consumption. In this design, the main CPU is set to 204 MHz, providing a good trade-off between speed and energy efficiency.
### 3. Test Results and Discussion
Through continuous hardware optimization and dynamic power management, the power consumption of the smartphone was measured in both idle and sleep modes. The results showed a reduction of 10.2 mA in idle mode and 1.5 mA in sleep mode. The wireless modem, with its own power management module, consumed about 3 mA consistently.
Compared to the unoptimized design, the optimized smartphone achieved significantly longer battery life. This demonstrates that effective power management techniques can greatly improve smartphone performance and user experience.
As mobile technology continues to evolve, low-power design will become even more critical. Emerging technologies like advanced power management chips and processors offer new opportunities for further reducing smartphone power consumption. However, designers must continue to focus on optimizing both hardware and software to ensure efficient and reliable performance. Only then can smartphones meet the growing expectations of users.