#the4thLichuangcompetition# Low power consumption dynamic current, voltage, power consumption record table

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[Please fill in during the registration stage↓] * Brief introduction to the work: Low cost, low power consumption, power consumption record sheet. Can measure the voltage and current of the device under test. And calculate the power consumption of the device based on time. Sampling once per second, the lowest average current can reach 30ua. A 1600mah lithium battery can last for at least 50,000 hours. Overvoltage, overcurrent alarm. Integrated an adjustable voltage source, input voltage 4.5-26V, output 2-24V, maximum current 2A.

[Please fill in during the competition stage↓] * 1. Details of the work; Low power consumption record sheet. There are three modes: 1. Low power consumption mode, the serial port outputs measurement results once per second, the average current is below 30uA when off, and 300ua when on. In this state, the test is instantaneous current and voltage, and the main control and AD sampling only work about 10ms per second. It is more suitable for equipment that requires long-term monitoring and does not have sudden current. The advantage is that it has low power consumption and can be powered by batteries. The disadvantage is that it measures instantaneous current and voltage, and the data is not real data. 2. In normal mode, the serial port outputs 4 measurement results per second, and when off, the average current is about 350ua. The display is about 600ua when turned on. In this state, the AD chip works full time, collecting voltage once every 140us, collecting current once every 140us, and the sampling frequency reaches 3500Hz. Calculate the average value after collecting data 1024 times. This sampling time is 286.72ms, and the main control is in sleep state. So it wakes up every 286.72ms to read data. In this mode, the current in the measurement circuit is always under the monitoring of the AD chip, and the data collected is relatively accurate. However, what is obtained is average data and real-time data cannot be obtained. 3. High-speed mode, this mode does not sleep, the microcontroller reads data and sends data continuously. The data collected is the same as in normal mode. However, the microcontroller can get more sampling data, about 60 times per second, which can be sent through the serial port. Working current 30ma. This mode does not improve measurement and is not cost-effective.

Circuit parameters 1. Measure voltage, range 0.001V-36V, accuracy +-2mV. 2. Measure current, range 0.0001A-2A, accuracy +-0.1mA. 3. Three working modes are available. 4. Low cost, using STM8L152 main control, INA226 current and voltage detection chip, and low power consumption 12864 LCD screen. The entire circuit board is low cost. (The main reason is that this general-purpose low-power screen is quite expensive, and it will be much cheaper to use a customized low-power screen) 5. The power of the device under test can be recorded by time and the power consumption within the time period can be calculated. 6. Integrate an adjustable voltage source, input voltage 4.5-26V, output 2-24V, maximum current 2A. (After adjustment, you can charge the lithium battery and do some protection.) 7. The voltage and current alarm values ​​can be set, and the alarm can be prompted for overvoltage and overcurrent.

* 2. Describe the challenges faced by the work and the problems it solves; The main difficulty is to consider the balance of the product. It must be cheap, the accuracy must not be too low, and the most important thing is that the power consumption must be low. The main focus of the circuit designed this time is cost-effectiveness. 1. The main control should have low power consumption, moderate price and high stability. Therefore, the very mature STM8L series products were selected. Most usage environments do not require a sampling speed of KHz, and since it is a low-power product, it means that the power consumption of the product itself is low, so there is no need to choose a high-speed MCU. 2.AD chip. The INA226 chip from TI was selected. Compared with the 12-bit AD of the microcontroller, this product is a 16-bit AD. In actual tests, this AD chip is more stable and more accurate than the AD that comes with the microcontroller. The price is also reasonable. 24-bit chips are relatively expensive, and the circuit and peripheral requirements are too high, which will greatly increase the cost. 3. Low power consumption setting, when the lowest power consumption is used, the sleep mode is used to wake up intermittently. Sampling once in 1S, each AD sampling takes about 10ms, and updating the LCD display takes about 80ms (a customized low-power segment code screen can greatly reduce this time, thereby greatly reducing the power consumption of the entire circuit). The current that the LCD screen maintains displaying is 60uA. The current in sleep mode is 11uA. On average, the power consumption when the display is not turned on should be around 50uA. The display is around 300uA when it is continuously on.

* 3. Describe the key points involved in the hardware and software parts of the work; The main consideration for hardware is how to ensure low power consumption of the entire circuit and the selection of components. To ensure the stability of AD sampling current, some small functions are added. In terms of software, it mainly does low-power sleep, wake-up sampling, data recording, and LCD screen display. Directly cut off power to circuits that are not in use during hibernation. To achieve low power consumption, sleep time should be allocated reasonably, working time should be shortened as much as possible, and parts that are not working should be powered off as much as possible.

  4. List of materials for the work; main components 1.STM8L152R8T6 2.INA226 3.SY8303 4.XC6201 5.AO3401 6.12864 LCD screen 7. Buttons 8. Terminals 9. Resistors, capacitors   5. Upload pictures of the work; (Contest must be on the PCB Mark the logo and take a photo to upload. Failure to do so will be deemed as giving up the competition)

* 6. Demonstrate your work and record it as a video for upload; (The content of the video must include: introduction to the work; functional demonstration; performance test; close-up of the competition logo on the PCB. Failure to do so will be deemed as giving up the competition) https://diy.szlcsc. com/attachments/2019/9/bmaXqffscT739YFeC8FFnY3PBgnFuEoWzMzscByP.mp4    7. Open source documents.