99iot AF-W12xTx User Manual

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Design Manual of AF-W12xTx Module Hardware

1.2 Basic characteristics of module...........................................................................2

1.3 Module type ........................................................................................................2

1.5 Block diagram of hardware.................................................................................4

2.2 Reset pin..............................................................................................................5

2.3 Reference circuit design......................................................................................6

6.2 Directions for module layout ............................................................................10

V1.1 2017.08

Contents

1 Introduction...............................................................................................................2

1.1 Abstract ............................................................................................................... 2

1.4 Sketch map of module.........................................................................................3

2 Design issues of hardware ........................................................................................ 5

2.1 Power design .......................................................................................................5

3 Application programming interface..........................................................................7

4 Log serial port ...........................................................................................................8

5 Communication serial port........................................................................................9

6 RF design and layout issues......................................................................................9

6.1 RF selecting resistor.......................................................................................... 9

6.3 Advice on module layout ..................................................................................11

7 Purchase and support ..............................................................................................12

Patent statements
2017 99 IoT (Shenzhen) Co., Ltd. reserves all rights for this document. Any part of the
document is not allowed to be reproduced, stored in any retrieval system or transmitted in any
form that has not been unified in written form by 99 IoT (Shenzhen) Co., Ltd.

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1 Introduction

 Supporting Simple Configuration intelligent networking function (APP is provided)

 Supporting Amazon, Baidu cloud, Jingdong cloud, Ali cloud

Module name

Module description

AF-W121TI

PCB onboard antenna

AF-W121TO

IPEX outer antenna (optional)

AF-W123TI

PCB onboard antenna

AF-W123TO

IPEX outer antenna (optional)

1.1 Abstract

The document mainly lists the issues that need attention in all stages during the use of

99 IoT Wi-Fi module AF-W12xTx design by users in order to reduce design costs and

increase product stability as far as possible.

AF-W12xTx is a complete and self-contained WiFi network solution module that can

run either in MCU+WIFI mode or as a slave on other master MCU. The sensor and

other applied specific devices can be integrated through GPIO port.

1.2 Basic characteristics of module

 Standard: 802.11 b/g/n 1x1

 Working mode: STA, AP, STA+AP

 Complete IoT solution (SDK, Cloud service, APP)

 Each module has unique global MAC ID

 Antenna: outer antenna, IPEX antenna interface, onboard antenna

 Working ambient temperature: -20 to 85℃

1.3 Module type

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1.4

引脚 名称 /主功能 类型 可选功能

Pin Name/ main function Type Optional functions

其它功能

Other

functions

1

GND

2

Wi-Fi-ANTENA

3

GND

4

NC/GND

5

CHIP_EN(RESET)

I

Reset

6

GPIOA_14

I/O

PWM0/ SWD_CLK

7

GPIOA_15

I/O

PWM1/ SWD_DATA

8

GPIOA_0

I/O

PWM2/EXT_32K/WL_LED

9

GPIOA_12

I/O

PWM3

10

GND

11

VDD33

12

GND

13

VBAT_MEAS

14

GPIOA_5

I/O

SDIO_SIDEBAND_INT/ PWM4

15

GPIOA_18

I/O

UART0_RXD/SPI1_CLK /SPI0_CLK
I2C1_SCL /

/

SD_D2/ TIMER4_TRIG/

I2S_MCK

16

GPIOA_19

I/O

UART0_CTS/SPI1_CS/SPI0_CS
I2C0_SDA/SD_D3/TIMER5_TRIG

I2S_SD_TX

Sketch map of module

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17

GPIOA_22

I/O

UART0_RTS / SPI1_MISO/
SPI0_MISO / I2C0_SCL
SD_D0 / PWM5 / I2S_WS

18

GPIOA_23

I/O

UART0_TXD/ SPI1_MOSI/
SPI0_MOSI / I2C1_SDA
SD_D1 / PWM0

19

GPIOA_30

I/O

UART2_Log_TXD/ I2C0_SDA/
PWM3 / RTC_OUT

20

GPIOA_29

I/O

UART2_Log_RXD / I2C0_SCL
PWM4

21

GND

Note:

1.5

Block diagram of hardware

AF-W121Tx/AF-W

123Tx

Backup register forpower

save SRAM16B

P

MU

3.3V

Inp

ut

256

K

SRA

M

ARMCM4F-M

CU

125MHZ ormor

e

512

K

R

OM

Digit

al

Sensor

ExternalFLAS

H

2M（Upto

128M

）

GDM

A

12

VBAT_MEA

GTIMER

6set

s

SPI

Master/Salve

I2C

Master/Salve

SDIO/USB

Device

SoC

ON

2.4G

HZ

S

witch

Bus

WIFI-802.11b/

g/nMAC

GPIOs *

11

PWM *

6

I2S

RTC

SW

D

UART *

2

ADC

AP

/

CloudServer

1. PIN19, 20 are for the use when Wi-Fi debugs LOG information input and output

port.

2. PIN19 of module AF-W121Tx needs to be pulled up to 3.3V externally, or floating,

or to ensure that power-on time isn’t low level.

3. Please keep CHIP_EN or other pins floating if they are not used.

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2 Design issues of hardware

（1）Input pin of main power supply is [PIN11], module supply voltage is DC 3.0～3.6, filter

capacitor of 4.7-10uF needs to be placed near its location; loading capability of 3.3V

（4）[PIN13] is ADC input pin, which can be used to detect battery voltage.

（1） [PIN5] is module reset pin: CHIP_EN（RESET）, needs to be pulled up by connecting

resistor of 100KΩ to power supply of 3.3V. The module will be in shutdown mode for

low level.

（3） If other MCU is needed to reset-control the module through the pin, a low pulse signal is

【ONSEMI/MAX809STR/SOT23/LM1117-3.3】. It can also be monitored by other

2.1 Power design

As shown in Figure 1.4 above

power supply, the power supply with rated output current ≥500mA is recommended.

（2）Use of DC/DC powerchip: voltage output meets 3.3V and the maximum current output

meets 500mA, input capacitor is as close as possible to voltage input pin, thickening

ground wire width or grounded copper area, punching more via holes for different layers.

（3）For LDO design, the voltage output meets 3.3V and the maximum current output meets

500mA, paying attention to device junction temperature, the formula of power

consumption is PD=(Vin-Vout) * Iload + Vin * IGND, in which Vin is input voltage,

Vout is output voltage, Iload is load current, IGND is ground current.

Reset PIN

2.2

As shown in Figure 1.4 above

（ 2 ） If the module is not controlled by other MCU, the decoupling capacitor of 100nF is

recommended to be added near its location to enhance the stability of the system.

needed and the duration of low level is at least 10ms.

（4） If the voltage of power supply is unstable (lower than 3.0V), it may cause module halt.

It is recommended to add Brown out reset circuit, and the recommended chip is as

follows:

(master control) MCU.

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2.3 Reference circuit design

Reference circuit design of module AF-W121Tx/AF-W123Tx, 5V to 3.3V conversion

5V to 3.3V conversion, LDO reference circuit design

Reset reference circuit design

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UART level switching circuit

Default: R64, UART 3V3 IO

UART T/RX

when UART T/R

3 Application programming interface

（3） The module uses SWD port for programming debugging, the PINs (module PIN6, 7)

LED flashes when

The pin will pull low up

（1） Users can use simulation tool and build environment for debugging.
（2） SWD port can be used to achieve DPA programming (master computer software does not

open temporarily).

need to be connected are shown in following figure:

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Log serial port

（3） Serial port pinboard is used to achieve AT Conmand operation by connecting

（4） Serial port pinboard is used to achieve firmware programming by connecting

abovementioned PIN.

4

（1） PIN19 is a boot PIN:

Level Function

0 Download image from UART

1 Boot from Flash

（2） Serial port pinboard is used to observe output log by connecting abovementioned PIN to

find abnormity of module software conveniently.

abovementioned PIN.

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5 Communication serial port

6.1 RF selecting resistor

R4

R3

R5

R5 selects onboard antenna.

In general, it is recommended to communicate with other MCU through this serial port,

the pins which need to be connected are shown in following figure: [PIN16], [PIN17]

are optional. These two pins are used to achieve fluid control.

6 RF design and layout issues

Selecting RF antenna through
above selection of 0Ω resistor:
R3 selects [pin5] RF pin;
R4 selects IPEX outer antenna
pedestal;

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6.2 Directions for module layout

（2） The module must be placed vertically with the onboard antenna top located

layout forbidden area.

（1） When using onboard antenna, layout forbidden area is seen in the figure

below;

or the module is placed horizontally with component side up;

（3） When the module is placed vertically, the clear height of module’s both

sides is at least over 12mm;

When the module is placed horizontally, the clear height under the module is

over 6mm;

Cable and other metals are prohibited above the module;

（4） Neither can copper be cladded nor can metal devices, sensors, interference

sources or other materials that have an impact on signal be placed under the

Layout forbidden area

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Layout forbidden area

Layout forbidden area

6.3 Advice on module layout

PCB is hollowed under the antenna.

12mm

2mm

Layout forbidden area

12mm

2mm

2mm

12

m

m

Layout forbidden area

2

m

12mm

When users use the module with onboard PCB antenna, they can put the module in the

following areas of the baseboard, or place the antenna of module outside the

baseboard, so the module onboard antenna has a larger clearance area compared to the

bottom to reduce the impact of metal devices on PCB antenna and wireless signals. Or

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Updating description of historical versions

Revision

Release Data

Summary

V1.0

2017/03/10

First draft

V1.1

2017/08/15

Adding module layout description,

firmware download description

Created by： Frank Wong

Date：8/15/2017

7 Purchase and support

Tel. [phone]

E-mail: [e-mail]

[e-mail]

Address: 609C north block, Cangsong Building, Tairan Seven Road, Futian District, Shenzhen

Website: www.sz99iot.com

*RF warning for Mobile device:
This equipment complies with FCC radiation exposure limits set forth for an uncontrolled environment. This equipment
should be installed and operated with minimum distance 20cm between the radiator & your body.

§ 15.19 Labelling requirements.

This device complies with part 15 of the FCC Rules. Operation is subject to the following two conditions: (1) This

device may not cause harmful interference, and (2) this device must accept any interference received, including

interference that may cause undesired operation.

§ 15.21 Information to user.

Any Changes or modifications not expressly approved by the party responsible for compliance could void

the user's authority to operate the equipment.

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§ 15.105 Information to the user.

Note: This equipment has been tested and found to comply with the limits for a

Class B digital device, pursuant to part 15 of the FCC Rules. These limits are designed to provide reasonable

protection against harmful interference in a residential installation. This equipment generates uses and can

radiate radio frequency energy and, if not installed and used in accordance with the instructions, may cause

harmful interference to radio communications. However, there is no guarantee that interference will not occur

in a particular installation. If this equipment does cause harmful interference to radio or television reception,

which can be determined by turning the equipment off and on, the user is encouraged to try to correct the

interference by one or more of the following measures:

-Reorient or relocate the receiving antenna.

-Increase the separation between the equipment and receiver.

-Connect the equipment into an outlet on a circuit different from that to which the receiver is connected.

-Consult the dealer or an experienced radio/TV technician for help.