A couple of words
Sorry for the long pause due to work and personal reasons. Next, I will continue to update, including but not limited to LoRa. The article will still be original according to personal habits, one is to use it as your own notes, and the other is to share and communicate with the majority of engineers.
The definition of LoRaWAN is a wireless communication protocol for Low power, long range application scenarios, so there are two key parts: 1. Low power consumption 2. Long distance
Among them, the long distance is currently completed by the wireless communication method of LoRa, because it has an ultra-low sensitivity of -148db in its parameters, which enables it to have a longer communication distance under the same transmit power.
Then there is the low power consumption. Let me talk about the low power consumption of LoRaWAN.
Note: I will not talk about the CAD mode next, just how the LoRaWAN protocol achieves low power consumption in the mechanism, and what the specific power consumption value is.
LoRaWAN CLASS A power consumption
As a rule, talk about hardware first and then software. Here press STM32L051C8T6 with SX1278
Chip power consumption
SX1276
- 休眠功耗:200 nA
- 接收电流:10mA
- 发射电流:20dB 120mASTM32L051C8T6
- 休眠功耗(RTC):1uA
- 32Mhz全速运行功耗:3mAProtocol power consumption
The working logic of class A is
send packet->sleep 1->RX1->sleep 2->RX2->sleep 3
The duration of sleep 1/sleep 2 is 1S, the duration of RX1/RX2 is about 50ms, the duration of packet sending is calculated according to SF12 BW125 (300 bps), the load length is calculated according to 17bytes, and the packet sending time is about 1000ms
Using these parameters to calculate, assuming that the device is powered by a battery, the battery power is 1000mAH, and a packet is sent every 1 hour, then the device can theoretically be used for 10 years! ! !
And this is still sending packets at the lowest rate in LoRaWAN!!!
What is this concept? At present, NB-IOT is considered to be the lowest power consumption communication method in the operator's network. According to the same working logic, it can only be used for more than one year. The specific difference will be discussed later.
This is Class A, as the lowest power operation in the low power protocol LoRaWAN.
I don't talk about Class B, because I have little contact with it, and it is difficult to implement, and it is rarely used on the market.
CALSS C:
The purpose of class c is to maximize the reception. This application scenario is generally a device that is often powered, so it is meaningless to discuss the power consumption of this device here.