Low power consumption design of single chip microcomputer

General Principles and Design Strategies of Low Power Consumption Design of Single Chip Microcomputer System

With the development of electronic science and technology, electronic products based on single-chip system design are widely used in people's production and life. At the same time, higher requirements are put forward for the design of power consumption of single-chip systems. Attracting people's attention, the low power consumption design of single-chip microcomputer meets the social energy-saving requirements, which can greatly improve the service life of electronic products and greatly improve product competitiveness. It can be seen from this that the low power consumption design of the single-chip microcomputer not only has good economic benefits, but also has greater social benefits.

1. Design principles of low power consumption of single-chip microcomputer system

(1) The principle that the CPU core should be simple: In the design of single-chip microcomputer system, the choice of CPU cannot blindly pursue performance. An 8-bit machine is enough, and the principle of enough is enough must be followed. With the development of science and technology, the current single-chip microcomputer runs faster and faster, but the continuous improvement of performance will definitely bring energy consumption. A relatively complex CPU must also have a high degree of integration. Because there are many transistors on the chip, the total leakage current will increase, so when the device is in the stop state, leakage will also occur. Therefore, the choice of CPU should be simple and practical. Reduce power consumption and can reduce costs.

(2) The principle of "enough is enough" for the voltage system: reducing the power supply voltage of the single-chip microcomputer can reduce the power consumption very well. At present, the power supply voltage of the single-chip microcomputer has dropped from the original 5V to 1.8V. Low-voltage power supply can effectively reduce the system operating current, but because the size of transistors is constantly decreasing, this is also a very disadvantageous aspect of reducing power consumption. Therefore, you must be careful when choosing a low-voltage system. Other electronic components in the system must work properly at low voltages. In this way, the problem of low power consumption of the system can be solved to a great extent.

(3) The principle of selecting low-power circuits: In the design of single-chip low-power systems, it is necessary to choose circuits that maintain high efficiency under low power consumption. At present, most low-power systems use HCMOS integrated circuits, which can integrate many The integrated circuits are joined together in one package. This reduces bus capacitance, allowing more signals to be accommodated. In addition, reducing the frequency of the crystal oscillator can also effectively reduce the current of the whole machine, but the reduction of the frequency of the crystal oscillator will sometimes affect the operating speed of the system, which will be limited by the timing of the external circuit, the frequency of counter measurement, and the frequency of serial communication. When selecting the frequency value, the working speed of the system information processing must be taken into consideration.

2. The main basis for low power consumption design of single chip microcomputer

2.1 Reduce the power consumption of single-chip application system

In the low-power system design of single-chip microcomputer, it is necessary to use power-down, sleep and interrupt reasonably to further realize the low-power operation of electronic products. Sleep mode and power-down mode can reduce power consumption by shutting down the CPU and the system. Purpose. Concentrate on tasks with large power consumption, reduce power consumption time, and adopt fast entry into power-down or sleep state to avoid unnecessary waiting of the system. On the premise of ensuring the normal operation of the system, reduce the acquisition speed and bus speed.

2.2 Essential low power design of MCU

The essential low power consumption design of the microcontroller is mainly reflected in the selection of components and circuit design. The selection of components should follow the principle that the frequency should be slow rather than fast, the system should be static rather than dynamic, and the voltage should be low rather than high, so as to realize the energy saving of the hardware system. The main methods of energy-saving control of components are: control of power supply voltage, clock control and static control. In the circuit design process, it is necessary to adopt a low-power wake-up circuit design, choose an electronic chip with a high degree of integration to replace an electronic chip with a single function and a low degree of integration, and strengthen the shielding and anti-interference ability of the circuit while reducing the power supply voltage design.

3. Low power consumption design scheme of single chip microcomputer system

3.1 Hardware design of single chip low power consumption system

(1) Choose an appropriate oscillation mode: Currently, the commonly used oscillators include crystal oscillator, resonator and RC oscillator. The wake-up time of the three oscillators is different. This design uses a crystal oscillator. The wake-up time of the crystal oscillator The time is about 8.5ms. During the working process of the microcontroller, if the wake-up time is too long, a pre-working stage will be formed. At this time, the processor will consume power, but the program is not running, so the power consumption will be lost. In order to further save energy consumption, a small resistor RS is connected in series in the circuit of the crystal oscillator.

(2) Dealing with I/O pins: In the design of single-chip low-power consumption systems, the handling of I/O pins is particularly important. The pins set as output can drive 20-25mA current, so it is necessary to optimize each output pin. In order to achieve the effect of energy saving, the internal pull-up can be disabled and the external larger resistor can be used as the upper position. This method can To save energy in the sleep state, in the disturbed environment, the current consumption will be increased due to the frequent flipping of the internal latch. Therefore, useless pins can be set as output instead of simply not connected. Once an external interference signal appears, it will easily become an input signal that repeatedly oscillates, causing unnecessary power consumption.

(3) Select the appropriate MCU and standby mode: Low-power MCU plays a very important role in reducing the power consumption of the single-chip microcomputer. It is necessary to select the most appropriate mode from various standby modes according to the specific occasions where the single-chip system is applied. mode, the MCU is in a low power consumption state as much as possible. When the operating frequency of the MCU is different, the difference in power consumption will be great. In addition, the low-voltage power supply can greatly reduce the power supply current of the system, and reducing the power supply voltage of the single-chip microcomputer can effectively reduce power consumption. Therefore, choosing an appropriate MCU and system voltage has positive significance for reducing power consumption.

3.2 Software design of single-chip low-power system

(1) Adopt the "interrupt" method to reduce power consumption: During the running of the system, the interrupt mode of the program is different, and the power consumption of the application system is very different. In the form of "interrupt", the system processor can be in the In the idle state, and in the form of query, the CPU will keep accessing the I/O registers, resulting in extra power consumption.

(2) Intermittent operation of the I/O module: the I/O module must pay attention to turning off the power supply during intermittent operation. Currently, the driver used in the single-chip application system generally has a large power, so an I/O pin must be used to perform the operation. Take control, when the system does not need to communicate, turn off the driver in time. For simple encapsulation or single-chip microcomputers without leads, attention should be paid to the initialization of I/O pins.

(3) Reduce the amount of CPU computation: In actual operation, there are many ways to reduce the computation amount of the CPU. The calculated results can be embedded in the Flash in advance, and the calculation can be replaced by querying during use. , thereby reducing the amount of CPU operations. Many single-chip microcomputers already have fast addressing modes and look-up table instructions, which are very effective for some unavoidable calculations. Increase the use of fractional operations or reduce the use of floating-point operations, and use some short data types as much as possible.

(4) Select the low power mode system: The low power mode mainly refers to the waiting or stop mode of the system. In this mode, the power of the single-chip microcomputer will be much smaller than the running power. In the waiting mode, the CPU will stop working, but the peripheral I/O modules of the single-chip microcomputer will not stop working, and the power consumption of the system will be reduced.

Taking Freescale's HCS08 microcontroller as an example, the power consumption of the system under different operating modes is given. HCS08 is an 8-bit single-chip microcomputer, there are many series, and the number of I/O modules in each series is different, but the current consumption in low power consumption mode is roughly the same.

Therefore, before letting the system enter the deep stop state, important system parameters should be saved in non-volatile memory, such as EEPROM. The deep stop mode turns off all I/O, and the possible wake-up methods are also very limited. Generally, it can only be reset or IRQ interrupt. The more reserved I/O modules, the more interrupt sources the system allows to wake up. The power consumption of the single-chip microcomputer will be reduced to between 1 μA and tens of μA according to the different reserved wake-up methods.

Summarize

In the development of today's society, the application of low-power single-chip microcomputer has become the main development direction of single-chip system design, and it has important practical significance to strengthen and promote the research of low-power consumption design of single-chip microcomputer. In the future research and design, through the design and innovation of the hardware system and software system, the single-chip microcomputer application system will create greater economic and social benefits in the near future.

The above is the general principle and design strategy of the low power consumption design of the microcontroller system introduced by Shenzhen Zuchuang Microelectronics Co., Ltd. for you. We have rich experience in customized development of smart electronic products, can evaluate the development cycle and IC price as soon as possible, and can also calculate the PCBA quotation. We are the agent of Sonix MCU and Yingguang MCU agent, selling and developing MCU and voice IC solutions of Sonix and Yingguang. We act as an agent and develop ICs and solutions of Jieli, Ankai, Quanzhi, realtek and other series, and also develop BLE Bluetooth IC, dual-mode Bluetooth module, wifi module, and Internet of Things module. We have hardware design and software development capabilities. Covering circuit design, PCB design, single-chip microcomputer development, software custom development, APP custom development, WeChat official account development, voice recognition technology, Bluetooth development, wifi technology, etc. It can also undertake the research and development of smart electronic products, the design of household appliances, the development of beauty equipment, the development of Internet of Things applications, the design of smart home solutions, the development of TWS earphones, the development of Bluetooth earphone speakers, the development of children's toys, and the development of electronic education products.