The actual performance of three LoRa modules in Meshtastic

Thanks to the author Yuri

Special thanks to Yuri Su, a senior member of the Meshtastic China community, for contributing important data, rigorous conclusions, and valuable test results to this article. This article expands upon his original contribution, and all the data comes from his patient and meticulous testing. As a frequent contributor to the community, Yuri has repeatedly shared valuable practical experience, and his support and efforts have furthered the development of the Meshtastic project in China. Simply put, without Yuri, this article would not be possible.

In order to ensure transparency and restore the author's original intention, the original submission has been folded to the end of the article. Interested friends are welcome to click to expand and view it.

Power consumption is a critical design factor in the Meshtastic project, especially when devices require extended standalone operation. As an open-source wireless mesh communication system based on LoRa technology, Meshtastic devices are often deployed outdoors, on rooftops, or in remote locations, relying on batteries and solar power. Therefore, testing the power consumption performance of different RF modules is crucial for optimizing device battery life and improving system energy efficiency.

First, power consumption is crucial for estimating the power consumption of solar nodes . In Meshtastic's application scenarios, by testing the power consumption data of different LoRa modules, we can accurately calculate the required battery capacity and solar panel power. For example, if a RF module consumes more power in receive mode, a larger battery capacity and a higher-power solar panel are required to ensure continuous operation in the absence of sunlight. Conversely, if the module consumes less power in idle mode, the required battery capacity and solar panel power requirements can be reduced, thereby reducing costs and extending device operation time.

Secondly, balancing power consumption with signal strength and price is another important consideration in Meshtastic device design. Meshtastic's core goal is to achieve long-distance, low-power wireless communication, but this doesn't necessarily mean lower power consumption is always better. In some application scenarios, devices may need to communicate stably over longer distances, requiring higher transmit power from the RF module, which in turn results in higher power consumption. Therefore, a trade-off must be made between power consumption, communication range, and cost.

Furthermore, Meshtastic devices typically operate in a low-power standby state, activating and transmitting data only when receiving advertising packets. Therefore, understanding the power consumption of different modules in the receiving state is crucial, as this directly impacts the device's energy consumption over the majority of its life.

This test will focus on comparing three common LoRa RF modules in the domestic market - the Silicon Transmission SX1268, the Ebyte E22 400MM22S, and the E22 400M22S, and analyzing their power consumption differences under the Meshtastic configuration.

We will test their transmit current, receive current, and average current in different operating modes to provide Meshtastic users with more accurate reference data on battery capacity, solar power supply, and device endurance. Furthermore, these test results will help us select the most appropriate RF module for specific needs, ensuring both communication quality and maximizing device energy efficiency.

Test environment

Each LoRa RF module was connected to a Pro Micro nRF52840 development board. All three boards were identical to ensure hardware consistency. The ProMicro nRF52840 is a development board based on the nRF52840 microcontroller and supports Bluetooth Low Energy (BLE), making it suitable as the master device for Meshtastic nodes. During testing, all boards ran the same Meshtastic firmware and maintained identical configurations.

To further simulate the actual Meshtastic application scenario, we adopted the following specific settings:

· Broadcast Interval: Set to 60 seconds to simulate the normal low-frequency information broadcast mode.

· Region : CN China

· Sending mode: LongFast

To simulate real-world hardware operation, each LoRa module was connected to a corresponding antenna. The SX1268 from Silicon Transmission used its original spring antenna, while the two Ebyte modules were equipped with their own external antennas.

Furthermore, the test device spent a significant amount of time in the receiving state, entering the transmitting state only when the broadcast interval was triggered, in order to align with the actual operating mode of the Meshtastic node. In practice, the broadcast interval is 10800 seconds, so the module spends most of the time in the receiving state.

To verify the configuration and obtain real-time operating status, the serial port command line output detailed Meshtastic operating parameters. The following are some key output contents, showing the initialization of the RF module, frequency setting, and operating mode:

Radio freq= 478.875 , config.lora.frequency_offset= 0.000 Set radio: region=CN, name=LongFast, config= 0 , ch= 35 , power= 19

myRegion->freqStart -> myRegion->freqEnd: 470.000000 -> 510.000000 ( 40.000000 MHz)

numChannels: 160 x 250.000 kHz

channel_num: 36

frequency: 478.875000

Slot time: 77 msec Set radio: final power level= 19

SX126x init result 0

Frequency set to 478.875000

Bandwidth set to 250.000000

Power output set to 19

Current limit set to 140.000000

Current limit set result 0 Set DIO2 as RF switch , result: 0

Use MCU pin 17 as RXEN and pin -1 as TXEN to control RF switching Set RX gain to boosted mode; result: 0

SX1268 init success

LoRA bitrate = 118.394310 bytes/sec

Test results

In this test, we conducted a comprehensive power consumption evaluation of three LoRa RF modules: the Silicon Transmission SX1268, the Ebyte E22 400MM22S, and the Ebyte E22 400M22S. These three modules represent widely used LoRa RF modules in the market and are also widely used in the Meshtastic China community.

· Silicon Transmission SX1268: This module uses an external antenna, and during testing, we used Silicon Transmission's spring antenna. Due to the module's relatively high transmit power and receive sensitivity, we expect its power consumption to be relatively high.

· Ebyte E22 400MM22S: This module uses the original antenna.

· Ebyte E22 400M22S: This module also uses the original antenna and is equipped with a temperature-compensated crystal oscillator (TCXO). In theory, a module equipped with a TCXO should consume more power, but in testing, we observed that its power consumption was lower than expected.

During testing, each module was driven by the same ProMicro 52840 development board, ensuring fairness and accuracy. The test environment, configuration parameters, and antenna selection remained consistent for each module, ensuring comparable test results.

We used a micropower analyzer to measure the power consumption of the three modules in different working states. The results are shown in the following table:

Silicon Transmission SX1268 power consumption

Ebyte E22 400MM22S Power Consumption

Ebyte E22 400M22S Power Consumption

Analyze

Emission current

As can be seen from the table, the three modules exhibit significant differences in their performance at maximum transmit current. The Silicon Transmission SX1268 has the highest transmit current, reaching 130mA, while the Ebyte E22 400MM22S has a relatively low current of 106mA, and the Ebyte E22 400M22S has a relatively low current of 139mA. Despite being equipped with a temperature-compensated crystal oscillator, the Ebyte E22 400M22S's transmit current is lower than expected, not higher.

Receive current

The SX1268 consumes the most power in receive mode, reaching 14.74mA. The Ebyte E22 400MM22S and E22 400M22S receive currents of 11.60mA and 8.12mA, respectively. The E22 400M22S has the lowest receive current, demonstrating its superior performance in low-power receive mode.

Average current and 24-hour power consumption

The average current draw of the Silicon Transmission SX1268 was 16.18mA, and its 24-hour power consumption was 388mAh, indicating relatively high power consumption. The Ebyte E22 400MM22S had an average current draw of 12.76mA and a 24-hour power consumption of 306mAh, slightly lower than the Silicon Transmission SX1268. However, the Ebyte E22 400M22S was the most energy-efficient, with an average current draw of only 9.79mA and a 24-hour power consumption of 235mAh, demonstrating its superior low power consumption.

Summary of results

In terms of maximum transmit current, the E22 400M22S performs similarly to the Silicon Transmission SX1268, but due to its lower receive current and lower average current, the overall power consumption is lower.

Although the E22 400MM22S is equipped with a temperature-compensated crystal oscillator, its power consumption performance in actual tests did not increase significantly as expected. Instead, it showed that its power consumption control was relatively efficient.

Overall, the E22 400M22S is the module with the lowest power consumption. Its current consumption in standby mode is much lower than that of the other two modules. It is very suitable for scenarios that require long-term operation and rely on solar power.

Actual scenario

Based on the above test results, we can calculate the required battery capacity and solar panel power requirements. Assuming that each device broadcasts a packet once an hour, the calculation is based on the test data.

24-hour battery requirement

In this test, we set the broadcast interval to 60 seconds, which is relatively short and higher than the frequency commonly used by members of the Meshtastic China community. Many users in the community typically choose longer broadcast intervals, such as 5 minutes, 10 minutes, or even longer. This means that actual power consumption may be lower than our test data. Therefore, when estimating battery requirements, we need to adjust it based on the specific broadcast interval and actual usage scenarios.

Taking the Silicon Transmission SX1268 as an example, testing revealed a daily power consumption of 388mAh. If your device has a longer broadcast interval or is in a receiving state for extended periods, the actual battery consumption will be lower than the test result. However, if the broadcast interval is shorter or the device transmits data frequently, battery consumption will increase. In this case, it is recommended to set the actual battery capacity requirement at three times the calculated value to ensure continuous and stable operation in dark or adverse environmental conditions.

For example, if daily power consumption is 388mAh, then to cope with environmental fluctuations and ensure the device can operate normally for a long time, the recommended battery capacity is 388mAh × 3 = 1164mAh. This capacity takes into account possible fluctuations in actual power consumption and the impact of environmental factors such as weather changes or unstable solar charging efficiency, providing greater assurance of device battery life.

Estimating the power required by solar panels

Assuming three cloudy days, the required battery capacity is 1164mAh × 3 = 3492mAh. If the solar panel can fully charge the battery in 5 hours, the required solar panel power is: 3492mAh / 5 = 698mA. Based on a 5V voltage, the solar panel power is: 698mA × 5V = 3.49W. This ensures stable operation even in extended periods without sunlight.

This also provides us with a preliminary basis for selecting solar panels to ensure that the equipment can maintain good working condition even when it is in a low-light environment for a long time.

 Author: Yuri_su | Community blogger

Translator:Joe Tan | KEEPTEEN | meshtastic node repeater

Website: https//www.keepteen.com

Article link:https://www.keepteen.com/blog-Solar-Lora-12710/The-actual-performance-of-three-LoRa-modules-in-Meshtastic-11941511.html