Design of 433M wireless module for CC1310 RF chip


  01. Introduction to CC1310

  1. feature

  The CC1310 is an important component of TI's family of sub-1GHz devices in high-efficiency/ultra-low-power wireless MCUs. wholesale Lora Wireless modems Design of 433M wireless module for CC1310 RF chip Very low active RF and MCU currents and low power mode current consumption ensure battery life and allow for the use of small coin cells in energy harvesting applications.


  The CC1310 device combines a flexible ultra-low-power RF transceiver with a powerful 48MHz Cortex-M3 microcontroller in a platform that supports multiple physical layers and RF standards. The dedicated wireless controller (Cortex-M0) handles low-level RF protocol commands stored in ROM or RAM to maintain low power consumption and flexibility. The CC1310 device does not achieve low power at the expense of RF performance; the CC1310 device offers excellent sensitivity and stability (selectivity and blocking) performance. The CC1310 device is a highly integrated, true monolithic solution that integrates a complete RF system with an on-chip DC-DC converter. The CC1310 power and clock management and wireless systems require specific configurations and are handled by software to function properly. This goal can be implemented in TI RTOS, so it is recommended that this software framework be applied to all application development processes for devices.

  2. Application

The CC1310 device can be used in various frequency bands such as 433M868M915M. It can also be used in automatic meter reading, home and building automation, wireless alarm and security systems, industrial monitoring and security control, wireless medical, active RFID and other fields.

  3. Package description

The CC1310 is available in three packages, 4mm x 4mm RSM VQFN48 (10 GPIO), 5mm x 5mm RHB VQFN48 (15 GPIO), 7mm x 7mm RGZ VQFN48 (30 GPIO). As shown below:

  

No matter which packaged chip is referenced on the 433M wireless module, the RGZ package 7X7 is used as an example to introduce the circuit design. The circuit is divided into two parts: the design of the schematic and the design of the PCB.

  02. Schematic Design

  The overall frame: power circuit, reset and crystal circuit, RF circuit and external pin circuit are composed of four parts.


  1.Power Circuit

 The power circuit is mainly divided into two parts: the power supply circuit and the power switch circuit inside the device. For the power supply circuit, the main purpose is to filter the processing to reduce the ripple to ensure the power supply is stable.

  

This part of the circuit is a power supply circuit. First, the power supply is connected to FL1 (fuse) as soon as it comes in, which acts as an overload protection. Then, to supply power to each power pin of the chip, a filter capacitor is needed to achieve a power supply and a filter capacitor to ensure the stability of the power supply.



  

This part of the circuit is the power switch circuit inside the device. When VDDR (ie DCDC_SW terminal) is equal to 1.95V and VDDS minimum voltage is 2.1V, the device can output about 14dBm in the 433M frequency band. In the PCB design, pay attention to L331 and C331 close to the 33rd pin DCDC_SW of the device, put the corresponding filter capacitor to the corresponding power supply pin (should be as close as possible to the power supply pin), and filter it.

  2.Reset and Crystal Oscillator Circuit


  The reset circuit is an ordinary RC circuit. The device has a high-speed clock 24M crystal oscillator circuit and a low-speed clock 32.768K crystal oscillator circuit. Generally, a 24M crystal oscillator circuit is used. Due to the matching capacitance of the 24M crystal oscillator inside the chip, the two matching capacitors C471 and C461 are generally reserved. The 32.768K crystal oscillator circuit is used as a reserve (usually not used), plus two 15pF matching capacitors.

  2. RF Circuit


  The RF circuit is mainly composed of a balun and a fifth-order filter. C15 is a DC blocking capacitor with a size of 330pF. Pay particular attention to the fact that C13 and C14 cannot be excessively increased during RF debugging, otherwise power will drop.

  4.Peripheral Circuit


  03. PCB Design

  1.Overall layout reference

  

The layout is mainly the layout of the RF circuit, and the layout between the inductor and the inductor is avoided to avoid mutual inductance, preferably vertical. China Wireless modems Manufacturers There is also the layout of the power supply circuit. As long as the power supply has a capacitance to the ground, it is better to add at least one ground via.


  2.Overall Wiring Reference

  

The layout directly affects the wiring. Note: Do not have a loop on the power wiring to avoid forming a power loop. RF wiring should be as short as possible to reduce the loss of RF signals.





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Ebyte IoT Wireless Communication Module


Ebyte IoT Wireless Communication Module: Application of SX127 Chip LoRa Wireless Module Technology in Wireless Meter Reading

Foreword

LoRa is an ultra-long-distance wireless transmission scheme based on spread spectrum technology adopted and promoted by Semtech. Test kits wholesalers This solution is no longer limited by the compromise between power consumption and transmission distance, and provides users with a system that can achieve long distance, long battery life, and multiple nodes, and then expand into a network. At present, the frequency bands of LoRa operation include 433, 868, 915MHz, etc., while the SX1278 RF chip LoRa module operates in the 137~525MHz frequency band.

Advantages of LoRa

LoRa has obvious advantages in anti-blocking and selectivity. Compared with traditional FSK and GFSK, it has stronger anti-interference ability and longer transmission distance. At present, it is mainly used in wireless meter reading, home and building automation, wireless alarm and security systems, industrial monitoring and control, remote irrigation systems, etc. The following briefly introduces the application of the SX1278 LoRa module in wireless meter reading.

The LoRa wireless meter reading system mainly includes four parts, wireless water and gas meters (built-in LoRa module), remote transmission gateway, network server, and terminal. The following is a brief introduction to the LoRa wireless water meter reading system, which is also applicable to gas meters.

Related parameters

Wireless water meters are equivalent to various terminal nodes and contain LoRa modules. We need to understand their basic functions and some related parameters:

1. Collection of water volume, built-in battery voltage and temperature

How to collect the data is not described in detail here. The collected data is mainly transmitted to the main MCU through the communication interface. Commonly used communication interfaces include TTL, RS232, and RS485 interfaces. The normal working voltage range of the SX1278 chip is 1.8~3.7V, and other chips also have a certain working voltage range. Here, it is necessary to set a low voltage standard for the alarm of the low voltage of the built-in battery. The normal working temperature range of the SX1278 chip is -40~+85℃. Similarly, other chips also have a certain working temperature range. Here it is necessary to set high and low temperature standards for temperature alarms.

2. Timely upload information

The collection of data does not involve wireless communication, but the information needs to be uploaded to the network server through the gateway (the gateway is equivalent to the base station). The uploading process involves the wireless communication of the LoRa module. At this time, we need to know the modulation mode of the current SX1278 chip configuration (the SX1278 chip supports FSK modulation at the same time), operating frequency, transmit power, air rate, etc. The SX1278 chip can work in the 137~525MHz frequency band. Of course, this requires different hardware circuits. When it is in sleep mode, the current is less than 1uA; when it is in receive mode, the current is about 15mA; when it is in transmit mode, it is about 100Ma@20dBm.

3. Switch, valve control

This function is downlink communication, such as forcibly closing the valve when an alarm occurs.

4. Other alarms

Such as magnetic interference alarm, to prevent damage to the built-in module of the wireless water meter, or inaccurate data collected such as water volume, built-in battery voltage and temperature.

The remote gateway part included in the LoRa wireless water meter reading system can also be called a concentrator or a base station. Generally, a cell is distributed with a base station, which is responsible for copying and collecting LoRa wireless water meters in the entire cell.

A gateway can correspond to multiple node devices, and data collection can be realized by polling. The gateway is connected to the back-end server through standard IP. These communications can be bidirectional. The communication between the node device and the gateway is based on different communication frequencies and air transmission rates. The selection of the air transmission rate requires a trade-off between transmission distance and message delay.

As can be seen from the above, the gateway does not process the data. The function of the gateway is to receive the data from the LoRa wireless water meter, and then transmit it to the back-end server through the operator's 3G or 4G network. At the same time, the gateway can also receive commands from the back-end server and transmit the commands to the LoRa wireless water meter.

The server part of the LoRa wireless water meter reading system needs to store and process data, and also includes various systems. The server mainly includes user management system, operation management system, business system, maintenance system, etc.

The functions of the user management system include the addition of new users, the deletion and modification of old users, etc.; the functions of the operation management system include regular meter reading, water consumption statistics, table export and user query, etc.; the functions of the business system include payment entry As well as detailed statistics, low water reminders, etc.; the functions of the maintenance system include LoRa wireless water meter running status collection and fault detection.

The LoRa wireless water meter reading system also includes a user terminal, which can be a PC or a mobile APP. The function of the terminal is mainly used for user login, user water consumption query and user online payment.

Epilogue

With the development of the Internet of Things, the application of the SX1278 LoRa module has become more and more extensive in recent years, and the technology has become more and more mature. Companies committed to the development of RF modules are also keen on the research of the SX1278 LoRa module. For example, the SX1278LoRa serial port module of Chengdu Ebyte Electronic Technology Co., Ltd. adds an error correction algorithm to the software, which greatly enhances the anti-interference ability; even more, adds PA and LNA to the hardware, which further improves the transmission distance. promote. In general, the development of the SX1278 LoRa module has not stopped, and the application is not only in wireless meter reading.

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