Introduction to Wi-Fi Module--WR4

Wi-Fi module introduction–WR4

1. Product Overview

​ WR4 is a low power-consuming built-in Wi-Fi module developed by Hangzhou Tuya Information Technology Co., Ltd. It consists of a highly integrated wireless radio chip (RTL8710BN) and an external flash chip, with a built-in Wi-Fi network protocol stack and robust library functions. WR4 also contains a low power-consuming ARM CM4F, a WLAN MAC, a 1T1R WLAN, a basic frequency of up to 125 MHz, a 256 KB SRAM, a 1 MB flash, and various peripheral resources.

​ WR4 is an RTOS platform that integrates all the function libraries of the Wi-Fi MAC and TCP/IP protocols. You can develop built-in Wi-Fi products as required.

​ Figure 1.1 shows the architecture of WR4.

1.1 Features

Built-in low power-consuming 32-bit CPU, which can also be used as an application processor

  • Basic frequency: 125 MHz

Working voltage:3 V to 3.6 V

Peripherals: nine GPIOs, one UART, and one ADC

Wi-Fi connectivity

  • 802.11 B/G/N20/N40

  • Channel 1–14@2.4 GHz

  • WPA/WPA2 security mode supported

  • +20 dBm output power in 802.11b mode

  • SmartConfig function supported (for Android and iOS devices)

  • IPEX connector for external antennas

  • Certified by CE, FCC, and SRRC

  • Working temperature: –40°C to +85°C

  • AES 128/256-based hardware encryption

1.2 Major Application Fields

  • Intelligent building
  • Intelligent home and household applications
  • Health care
  • Industrial wireless control
  • Baby monitor
  • Network camera
  • Intelligent bus

2. Module Interfaces

2.1 Dimensions and Footprint

​ WR4 provides two rows of pins (2 x 8) with the distance of 1.5 mm between every two pins.

​ WR4 dimensions: 13.8 mm (W) x 15.5 mm (L) x 3.3 mm (H) (see figure 2.1)

Figure 2.1 WR4 dimensions

2.2 Pin Definition

Table 2.1 describes the common pins. ​ Table 2.1 WR4 pins

Pin Symbol I/O Type Functions
1 NC / NC, not connected
2 ADC AI ADC interface, with the maximum output power of 5 V
3 EN I/O External enabled reset pin (active low)
4 A_19 I/O GPIOA_19
5 A_12 I/O GPIOA_12
6 A_0 I/O GPIOA_0, which cannot be pulled up during power-on and can be configured after power-on
7 A_5 I/O GPIOA_5
8 3.3 V P Module power supply pin (3.3 V)
9 GND P Power supply reference ground pin
10 A_23 I/O UART0_TXD (user’s serial port)
11 A_18 I/O UART0_RXD (user’s serial port)
12 A_22 I/O GPIOA_22
13 A_15 I/O GPIOA_15
14 A_14 I/O GPIOA_14
15 A_29 I/O UART_Log_RXD (used for printing of the module internal information), which can also be used as the GPIO
16 A_30 I/O UART_Log_TXD (used for printing of the module internal information), which can also be used as the GPIO

Note: P indicates power-supply pins, I/O indicates input/output pins, and AI indicates analog input pins.

3. ElectricalCharacteristics

3.1 Absolute Electrical Characteristics

​ Table 3.1 Absolute electrical characteristics

Parameters Description Minimum value Maximum value Unit
Ts Storage temperature -40 105
VDD Power supply voltage -0.3 3.6 V
Static electricity voltage (human model) TAMB-25℃ - 2 KV
Static electricity voltage (machine model) TAMB-25℃ - 0.5 KV

3.2 Electrical conditions

Table 3.2 Normal electrical conditions

Parameter Description Minimum Value Typical Value Maximum Value Unit
Ta Working temperature –20 - 85 °C
VDD Working voltage 3.0 - 3.6 V
VIL I/O low-level input –0.3 - VDD*0.25 V
VIH I/O high-level input VDD*0.75 - 3.6 V
VOL I/O low-level output - - VDD*0.1 V
VOH I/O high-level output VDD*0.8 - VDD V
Imax I/O drive current - - 16 mA
Cpad Input pin capacitor - 2 - pF

3.3 Wi-Fi TX Power Consumption

​ Table 3.3 TX power consumption during constant emission

Symbol Mode Power Typical Value Unit
IRF 11b11 Mbit/s 17 dBm 287 mA
IRF 11b11 Mbit/s 18 dBm 295 mA
IRF 11g54 Mbit/s 15 dBm 255 mA
IRF 11g54 Mbit/s 17.5 dBm 267 mA
IRF 11n BW20MCS7 13 dBm 244 mA
IRF 11n BW20MCS7 16.5 dBm 257 mA
IRF 11n BW40MCS7 13 dBm 220 mA
IRF 11n BW40MCS7 16.5 dBm 230 mA

Note: When the preceding data is used for testing, the amount of constantly emitted data (duty cycle) is 100%.

3.4 Wi-Fi RX Power Consumption

​ Table 3.4 RX power consumption during constant emission

Symbol Mode Typical Value Unit
IRF CPU sleep 90 mA
IRF CPU active 120 mA

3.5 Power Consumption in Operating Mode

​ Table 3.5 Module working current

Working Mode Working Status (Ta = 25°C) Typical Value Peak Value* Unit
EZ mode The module is in EZ status and the Wi-Fi indicator quickly flashes. 115 130 mA
Idle mode The module is in connected status and the Wi-Fi indicator is steady on. 50 110 mA
Operation mode The module is in connected status and the Wi-Fi indicator is steady on. 120 265 mA
Disconnection mode The module is in disconnected status and the Wi-Fi indicator is steady off. 35 90 mA

Note: The peak duration is about 5 µs. ​ The preceding parameter values vary depending on the firmware functions.

4. RF Features

4.1 Basic RF Features

​ Table 4.1,Basic RF features

Parameter Description
Frequency range 2.400–2.4835 GHz
Wi-Fi standard IEEE 802.11b/g/n (channel 1–14)
Data transmitting rate 11b: 1, 2, 5.5, 11 (Mbit/s)11g: 6, 9, 12, 18, 24, 36, 48, 54 (Mbit/s)11n: HT20 MCS0–MCS711n: HT40 MCS0–MCS7
Antenna type External antenna connected through the U.FL RF connector

4.2 WI-FI Output Power

​ Table 4.2 TX power during constant emission

Parameter Minimum Value Typical Value Maximum Value Unit
RF average output power, 802.11b CCK mode 11M - 17.5 - dBm
RF average output power, 802.11g OFDM mode 54M - 14.5 - dBm
RF average output power, 802.11n OFDM mode MCS7 - 13.5 - dBm
Frequency error -10 - 10 ppm

4.3 WI-FI RX sensitivity

​ Table 4.3 RX Sensitivity

Parameter Minimum Value Typical Value Maximum Value Unit
PER < 8%, RX sensitivity, 802.11b CCK mode 11M - –91 - dBm
PER < 10%, RX sensitivity, 802.11g OFDM mode 54M - –75 - dBm
PER < 10%, RX sensitivity, 802.11n OFDM mode MCS7 - –72 - dBm

5. Antenna Information

5.1 Antenna types

​ The FPC antenna is recommended. Figure 5.1 shows the recommended antenna connection method and the dimensions. You can also select standard antennas based on the product assembly method.

5.2 Antenna Interference Reduction

​ To ensure optimal Wi-Fi performance when the Wi-Fi module uses the onboard PCB antenna, it is recommended that there be a space of at least 15 mm between the module antenna and other metal parts.

5.3 U.FL RF connector

Figure 5.2 shows the U.FL RF connector parameters.

6. Packaging Information and Poduction Instructions

6.1 Mechanical Dimensions

6.3 Production Instructions

Storage conditions of a delivered module are as follows:

  1. The anti-moisture bag is placed in an environment where the temperature is under 30°C and the relative humidity is under 85%.
  2. The shelf life of a dry-packaged product is six months from the date when the product is packaged and sealed.


  1. Throughout the production process, each involved operator must wear an electrostatic ring.
  2. During the operation, strictly protect the module from water and strains.

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