How to minimize the power consumption of LoRa terminals? Reducing energy consumption has become an important issue for battery-powered products. The RNDU470T can reduce sleep energy consumption to the extreme, but how he achieved it, we will explain in detail.
Energy consumption is a major problem for battery-powered products. Once the power is exhausted, the device will “strike†and in some cases electrical energy means the life of the electronic product. In the Internet of Things era, more and more battery-powered devices will be connected via wireless communication, reducing energy consumption once again on the engineer's desktop—solving it.
The RMI terminal (referred to as the terminal) RNDU470T not only has the advantage of ultra-long-distance transmission of 5km in an open environment, but also reduces the sleep energy consumption to the extreme (0.4uA, with an RTC of 1.4uA). How did we do it? Next, decrypt step by step.
hardware design1. Use low power devices
The terminal MCU selects STM8L151C8T6, which belongs to ultra-low power consumption, 400nA without RTC sleep, and 1.4uA with RTC sleep. The MCU has a large RAM (4KB) and its own EEPROM (2KB), without the need to expand external storage devices, to reduce power consumption and cost in one step.
The terminal radio chip uses SX1278. In sleep mode, the power consumption of the chip is as low as negligible.
2. Let the RF module sleep as quickly as possible
The SX1278 is part of the LoRaTM spread-spectrum modulation technique, and its long-range advantage benefits from the modulation gain, not by increasing the transmit power (which would consume more power). The current consumption of the RF chip is as follows: sleep "0.2uA, idle = 1.6mA, receive = 12mA, transmit (maximum power) = 120mA.
The terminal MCU controls the SX1278 through the "interrupt + timer timeout" mode. Once the radio completes transmission or reception, it immediately enters sleep mode.
3. Understand the working mode and power consumption of the MCU
To reduce the power consumption of the MCU, first turn on the peripherals as little as possible, and then let them sleep as much as possible. Let's take a look at the power consumption of the STM8L151C8T6 in different operating modes.
The above low-power operation mode is a bit more for developers, especially the STM8L processor. We need general guidelines, and Table 2 below is the experience from practice.
4. Statically configure the MCU pin
Even if both the MCU and the RF enter sleep mode, they will “sneak†consume power if the MCU pins are not set. Take the STM8L151C8T6 as an example. It has a total of 48 pins. It needs to be classified by Excel first, as shown in the following example:
Generally speaking, the pins can be divided into five categories. You can use the "Metro Color Difference" method to design the following legend:
Features:
Bluetooth dialpad
Enter the number on the dial interface of the watch or mobile phone to enter the dial. The watch and mobile phone will be synchronized in real time.
Phone book
After connecting Bluetooth with your phone, phonebook contacts can be synced to your watch.
Call records
View recent call history of Bluetooth-connected devices.
Information
View phone information for Bluetooth connection with watc.
Motion record
Movement records three color circles, which represent the three data of step counting, exercise and standing
a. Step counting: according to the number of personal information target steps in the exercise record settings, the goal will be displayed full circle
b. Exercise: According to the physical fitness training exercise cumulative time reaches 30 minutes, full circle is displayed
c. Standing: stand and move for at least 1 minute per hour, and if the number of exercise steps reaches 25 steps or more in 1 minute, 1 ratio is recorded, and the target is divided into 12 ratios and a 12-hour full circle is required.
Heart rate
Enter the heart rate menu, the back of the watch must be placed on the skin of the arm, click on the start, the watch will automatically measure the heart rate value.
Blood pressure monitoring
Enter the blood pressure monitoring menu, the back of the watch must be placed on the skin of the arm, click start, the watch will automatically measure the blood pressure value.
Physical Training
Enter the fitness training menu, there are a total of 11 modes to choose from: 1, running 2, skipping 3, sit-up 4, table tennis 5, basketball 6, badminton 7, mountain climbing 8, riding 9, tennis 10, walking 11, Volleyball, you can choose any sport to start, record the current exercise time and calorie data.
Sedentary reminder
Click to enter the sedentary reminder interface, and slide the timing ring upward to enter the setting. After the set time period is determined, click Start. After the sedentary, the bell and vibration will remind you to get up.
Bluetooth connection
a. First turn on the Bluetooth switch of the watch, turn on the Bluetooth switch of the smartphone, and enter the Bluetooth notification menu. Click to automatically search for nearby Bluetooth enabled devices, find the phone device model and pair with it. After successful pairing, the Bluetooth icon in the status bar of the watch will display Green, at this time the watch and mobile phone successfully search for devices. (Via watch-search for equipment, there is vibration and ringing on the mobile phone end; through cellphone-finding device, there is vibration and ringing on the watch end)
b. Search, add, and delete Bluetooth devices, and the name and address of the device's Bluetooth can be viewed in About Phone.
Sleep detection
The watch wears the hand to sleep and automatically enters the sleep monitoring mode; automatically detects the length of your deep / light sleep all night and calculates your sleep quality; the APP can view the sleep data details.
Bluetooth music
After connecting the Bluetooth of the mobile phone, enter the Bluetooth music, click to control the music playback on the Bluetooth device.
Notice
Display information synchronized from the mobile phone, such as: QQ, WeChat, SMS, time, Twitter, Facebook, etc.
Set up
a, voice king (open and close, adjust the volume)
b. Side slip switch (open and close side slip function)
c. Security Settings (Password can be set arbitrarily, up to 8 digits)
d. Bluetooth Settings (enable and disable Bluetooth)
e. Raise the hand and light the screen (open and close the f. temperature unit (switchable Fahrenheit, Celsius)
g, the screen is always on (can be opened and closed)
h, clock (set time and date, change the time system, standby dial)
i, sound (set the incoming call ringing mode and incoming call notification bell ringing)
j, volume (set to adjust the multimedia, incoming ringtone and notification ringtone size)
k, Display (theme style: a variety of built-in UI styles can be switched at any time, set the screen brightness and backlight time
l. Language environment (multiple language modes can be selected)
m. Restore production Settings (this function will clear all the local call records, information, alarm clock, etc., please be careful)
n, About (check the device name and Bluetooth device address)
Recording
Enter the recording menu, click to start, pause, save the recording, and select to play the saved recording from the options menu
APP download
Scan the QR code on the watch side, you can download and install the Bluetooth notification application software.
Alarm
Add alarm reminders based on personal schedule.
Stopwatch
Turn the stopwatch timer on, off, and off.
Remote camera
After the watch is connected to an Android or IOS phone via Bluetooth, you can click the remote camera on the watch to control the phone to open the camera function to take a picture.
Note:IOS's mobile phone needs to enter the settings, click the linked device, then turn on the camera, and then click Remote photography
Search for my device
After the watch is connected to Android or IOS by Bluetooth, tap Search My Device on the watch and the phone will ring.
Calendar
Switching the interface up and down can jump to the date. Calculator
Used for calculation, supports up to 12-digit numerical display.
breathing
Used to adjust the breathing state, adjust the breathing according to the size of the icon
Blood oxygen
Enter the menu of blood oxygen, the back of the watch must be attached to the arm skin, the watch will automatically measure the value of bleeding oxygen.
Body temperature
Enter the temperature menu, the back of the watch must be attached to the arm skin, click "Start", the watch will automatically measure the temperature valueentertainment
Built-in some games, according to the game instructions to operate the entertainment
Music player
The built-in songs can be downloaded through USB, and can be played locally after the next good
Video player
The built-in video can be downloaded via USB, and can be played locally after it is finished
Application
a.Twitter(Turn on / off blocking message notifications)
b.Facebook(Turn on / off blocking message notifications)
c.WhatsApp(Turn on / off blocking message notifications)
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