A survey of Wi-Fi connectivity modules for IoT applications part 1

Wi-Fi connectivity has become important for many IoT ecosystems, enabling data exchange with cloud servers and facilitating real-time monitoring. This multipart FAQ on Wi-Fi connectivity for modules for IoT applications will focus on 10 prominent manufacturers and their modules that every electronics engineer should know. This first part focuses on Expressif Systems and Texas Instruments, which offer their Wi-Fi modules and unique benefits.

Espressif Systems: ESP32

The ESP32 Wi-Fi module has become common among beginners and experts in the IoT world. Espressif Systems, the company that made ESP32, has sold more than a billion chips since its Wi-Fi chips came out, showing their huge market share.

Figure 1 shows the ESP32 Wi-Fi module consisting of 38 pins that serve several purposes, including GPIOs, ADC/DAC, SPI, I2C, and UART. The module’s Wi-Fi specifications offer several key advantages for IoT applications, making it well-suited for connected devices.

Figure 1. Pinout diagram of ESP32 consisting of GPIOs, SPI, I2C, and ADC/DAC, which are useful in IoT applications. (Image: LastMinuteEngineers.com)

First, it supports 802.11b/g/n protocols and has up to 150 Mbps speeds, making it compatible with existing networks and giving most IoT apps enough bandwidth. This means that IoT devices can send sensor data, receive orders, and update their firmware without any problems related to network protocols.

Adding WMM (Wi-Fi Multimedia) features allows for controlling the quality of service (QoS), which is very important for IoT apps that need to send data in real-time or give certain types of traffic higher priority. For example, in a smart home system, important security alerts may be given more weight than normal temperature readings.

Along with Immediate Block ACK, the TX/RX A-MPDU and RX A-MSDU features make data transfer much more efficient. Multiple data frames can be sent as a single packet thanks to these methods for packet aggregation. This reduces overhead and extends battery life, which is very important for IoT devices that usually only have access to small amounts of power.

The hardware TSF (Timing Synchronization Function) and automatic beacon monitoring make it very useful for IoT apps that need to coordinate timing very precisely. This feature helps keep devices in sync without putting a lot of stress on the processor. It allows things like time-sensitive factory controls or synchronized sensor networks to work.

By giving IoT operations four virtual Wi-Fi interfaces, a lot of freedom is gained. This lets a single ESP32 device be a client, an access point, and a traffic monitor simultaneously, making it possible for complex networking setups. For example, one device could serve as a sensor node and a local gateway for other IoT devices.

Support for Infrastructure Station, SoftAP, and Promiscuous modes simultaneously offer more options for setting up and deploying devices. This is very helpful in IoT situations where devices must change jobs quickly or do more than one thing in the network architecture. For example, a gadget could gather data and give other sensors a way to connect locally to the internet.

Figure 2. Functional block diagram of ESP32 consisting of different units that successfully run the SoC. (Image: Espressif Systems)

Apart from the core Wi-Fi specifications explained above, the other specifications of ESP32 (Figure 2) are also useful for IoT applications.

As a dual-core processor with much processing power (994.26 CoreMark at 240 MHz), the ESP32 is perfect for managing wireless communications and solving complicated IoT tasks. It has 520 KB of SRAM and 16 KB of RTC SRAM in its memory, which is enough for IoT apps and data buffering.

Power management features are very important for IoT devices that run on batteries. For example, ESP32’s Deep-sleep mode uses only 10 µA of power, and ULP coprocessors let monitor sensors with little power. Secure boot, encryption, and hardware-accelerated cryptography are some of the security features that keep IoT devices and their data safe from people who should not be able to see or change them.

Texas Instruments: CC3200, CC335x and CC330x Modules

Texas Instruments has been a pioneering force in wireless connectivity, with significant milestones in Wi-Fi module development, such as SimpleLink™ Wi-Fi platform to simplify IoT connectivity and Internet-on-a-chip™ solutions for wireless applications. Their popular and most recent Wi-Fi modules include CC3200, CC335x, and CC330x.

CC3200 Module

The CC3200 is a single-chip wireless MCU developed for IoT applications that integrate multiple key components into a compact solution, as shown in Figure 3.

Figure 3. Functional block diagram of CC3200 SimpleLink™ Wi-Fi solution. (Image: Texas Instruments)

The specialized ARM MCU on the CC3200 module handles Wi-Fi and Internet protocols, a big plus for IoT devices. By taking these communication tasks off of the main application microcontroller, the system can focus on application-specific tasks more quickly while still being able to link reliably. Putting Wi-Fi and internet protocols into ROM makes this design even better by offering ready-to-use networking options.

The module fully supports networks, including 802.11 b/g/n standards, and has built-in MAC, baseband, and radio components that make it compatible with many different types of infrastructure. The TCP/IP stack implementation supports eight TCP/UDP sockets and two TLS/SSL sockets simultaneously. This makes it possible for complex IoT apps to connect to many things simultaneously, like sensor networks or smart home devices.

A specialized crypto engine supports 256-bit AES encryption for TLS and SSL connections, strengthening security features. This and the WPA2 Personal and Enterprise security choices strengthen the protection needed to send sensitive IoT data.

IoT devices can work with a variety of network structures because they can switch between operating modes (Station, AP, and Wi-Fi Direct). The SimpleLink™ Connection Manager and SmartConfig™ Technology make setting up devices and networks easier, simplifying deployment and lowering the upkeep cost.

Good range coverage is provided by the transmission power levels (18.0 dBm for DSSS and 14.5 dBm for OFDM), and the receiver sensitivity (down to -95.7 dBm) makes sure that contact is reliable even in difficult conditions. With 16 Mbps for UDP and 13 Mbps for TCP, the throughput is more than enough for most IoT apps, from simple sensor data transmission to more demanding ones like industrial automation or video surveillance.

CC335x and CC330x modules

The CC335x and CC330x modules are the newest from Texas Instruments and have earned a special mention in this article.

Wi-Fi 6 (802.11ax) technology is used in both modules, which is very helpful for IoT operations. Having OFDMA, MU-MIMO downlink, and trigger frame features makes handling communications between multiple devices easier. This is especially helpful in dense IoT environments where many devices compete for network access. The target wake time (TWT) feature is very useful for IoT devices that run on batteries because it lets precise schedules for when the device wakes up and goes to sleep, significantly lowering the power it uses.

Hardware-based encryption and decryption support for WPA2 and WPA3 ensures that IoT data transfer is safe without adding much extra work to the computer. This is very important for keeping operations running smoothly and private information safe. Figure 4 shows the basic system diagram of the CC330x module consisting of system components, interfaces, and Wi-Fi Core.

Figure 4. Basic system diagram of CC330x Wi-Fi and BLE companion IC. (Image: Texas Instruments)

Both units work well with each other and have 4-bit SDIO and SPI host interfaces, making them easy to integrate with various IoT system designs. The 2.4 GHz and 20 MHz bandwidth single spatial stream implementation hits a good mix between performance and power efficiency, making it good for most IoT uses.

Figure 5. Basic system diagram of CC335x Wi-Fi and BLE companion IC. (Image: Texas Instruments)

The CC335x (Figure 5) distinguishes itself with dual-band support (2.4 GHz, 5 GHz, and 20 MHz), offering additional flexibility for IoT deployments. This capability is particularly valuable in environments with high RF interference, allowing devices to switch to less congested frequency bands.

Summary

ESP32 from Espressif System is a household name for Wi-Fi modules in IoT applications. Its low price, compact form factor, and compatibility with numerous programming platforms, such as the Arduino IDE, make them a favorite. Texas Instruments offers a wide range of modules depending on the IoT applications, which makes them a good choice for industrial applications where custom Wi-Fi specifications are needed. The next FAQ will discuss Wi-Fi modules from u-blox and Microchip Technology and their various Wi-Fi specifications.