RAK1920 WisBlock Sensor Adapter Module Datasheet

Overview

Description

The RAK1920 module, a part of the WisBlock Interface series, is a sensor extension module, which extends the WisBlock system with an adapter board to connect Click Boards (MikroElektronika), QWICC (Sparkfun) based and Grove (Seeed) based sensors to WisBlock. This module was designed to be part of a production-ready IoT solution in a modular way and must be combined with a WisBlock Core and a Base module.

It supports several defacto-standard interfaces in the IoT market and allows you to integrate sensors manufactured by Mikroe, SparkFun, SeeedStudio, and others. For example, the RAK1920 supports the Click Boards™ series of modules provided by Mikroe, Qwiic Connect™ sensor interface designed by SparkFun. Also, it supports all kinds of I2C module digital I/O, UART, and ADC sensors with a Grove™ interface.

Features

• Interface to all Click Boards of Mikroe
• Interface to all Qwiic sensors of SparkFun
• Interface to all I2C and Digital I/O sensors of Grove
• Interface to UART and ADC sensors options of Grove
• Reserved I2C interface
• 3.3 V and 5 V sensors options

Specifications

Overview

The RAK1920 module supports Mikroe’s Click Boards, Sparkfun’s Qwiic Connect, and Seeed’s Grove sensors. Figure 1 shows the sensors’ connector available in the RAK1920.

Figure 4701: RAK1920 sensor extension interface

Mounting

Figure 2 shows how the RAK1920 module is integrated with the RAK5005-O baseboard, and the mounting sketch is also shown.

Figure 4702: RAK1920 Mounting Sketch

Hardware

The hardware specification is categorized into four parts. It discusses the interfacing, its corresponding functions and the diagram of the module as well. It also covers the electrical and mechanical parameters that include the tabular data of the functionalities and standard values of the RAK1920 WisBlock Sensor Adapter Module.

Interfaces

Mikroe Click Boards Interfaces

The RAK1920 supports all the Click boards modules manufactured by Mikroe through the mikroBUS™ interface. Figure 3 shows the pin out diagram of the mikroBUS.

Figure 4703: Mikroe’s mikroBUS® interface

Pin No.	Label	Pin Definition
1	A0	Analog
2	RESET	Reset
3	SPI_CS	SPI Chip Select
4	SPI_CK	SPI Clock
5	SPI_MISO	SPI Master Input Slave Output
6	SPI_MOSI	SPI Master Output Slave Input
7	+3.3 V	VCC 3.3 V Power
8	GND	Reference Ground
9	GND	Reference Ground
10	+5 V	VCC 5.5 V Power
11	I2C_SDA	I2C Data
12	I2C_SCL	I2C Clock
13	UART_TX	UART Transmit
14	UART_RX	UART Receive
15	INT	Hardware Interrupt
16	PWM	PWM Input

Grove Sensor Interfaces

The RAK1920 module supports the Grove I2C and digital I/O sensors. Figure 4 shows the pin number and definition of the Grove sensor. By default, VCC is connected to the 3.3 V line of the IO connector.

Figure 4704: Grove Sensor interfaces

By default, the I2C is enabled in the RAK1920 module, but if it is required, the RAK1920 module can also support sensors with Grove UART interface and ADC sensors. To enable the UART interface, a resistance connection needs to be added by the customer. When using the Grove UART interface sensor module, replace R9 to R10 and R11 to R12. When using Grove ADC interface (not ADC to I2C module) sensor module, replace R13 to R14 and change R15 to R16.

Figure 4705: Replace connection resistance location

Figure 6 shows Grove sensor cables:

Figure 4706: Grove Sensor cables

Table below shows Grove cable color and function definition.

Pin	Color	Function
1	Yellow	Digital IO1 /ADC CH1 /UART RX /I2C Cock
2	White	Digital IO2 /ADC CH2 /UART TX /I2C Data
3	Red	VCC
4	Black	GND

Qwiic Sensor Interface

The RAK1920 module supports sensors manufactured by SparkFun through the Qwiic Connect interface. Figure 7 shows the Qwiic Connect interface:

Figure 4707: Qwiic Connect® interface

Figure 8 shows a Qwiic Connect cable:

Figure 4708: Qwicc Cable

The table below shows the Qwiic Connect cable color and function definition:

Pin	Color	Function
1	Yellow	I2C Clock
2	Blue	I2C Data
3	Red	3.3 V
4	Black	GND

Reserved I2C Interface

The RAK1920 module has a reserved I2C interface, and it can be used for generic I2C interface sensors.

NOTE

The I2C interface only supports 3.3 V type of sensors. The reversed I2C interface is shown in Figure 9.

Figure 4709: Reserved I2C Interface

Electrical Characteristics

Absolute Maximum Ratings

Table below shows the absolute maximum ratings of the RAK1920 module:

Symbol	Description	Min.	Nom.	Max.	Unit
VBAT	Power supply for the module	-0.5		4.2	V
Iout	Boost converter output current			50	mA

Recommended Operating Conditions

Table below shows the recommended operating conditions of the RAK1920 module:

Symbol	Description	Min.	Nom.	Max.	Unit
VBAT	Power supply for the module	2.6		4.2	V
3V3	3.3 V power supply		3.3		V
5V	5.5 V power supply		5.0		V

Mechanical Characteristics

Board Dimensions

Figure 10: Mechanical Dimensions

WisConnector PCB Layout

Figure 11: WisConnector PCB footprint and recommendations

Schematic Diagram

Figure 12: Schematic Diagram

The following sections will describe the schematic of the RAK1920 module:

• Power Supply
• IO Connector

Power Supply

The RAK1920 module supports the 5 V option. By default, the 3.3 V_S is used as the 3.3 V power source of sensors. The module integrates a boost converter from the VBAT to 5 V. The VBAT is the battery output voltage, usually between 3.7 V and 4.2 V. The EN pin enables the boost converter and is controlled by the WisBlock Core module of the overall solution.

warning

The 3V3_S has to be enable via WB_IO2 GPIO. Otherwise, the module will not work.

Figure 13: Power supply

IO Connector

Figure 14: IO Connector

The RAK1920 module uses only a subset of all the pins available in the IO connector. These are shown in the table below:

Name	Description	Comment
VBAT	Battery output voltage	Maximum: 4.2 V
3V3	3.3 V	Default, sensor power supply
TXD1/RXD1	UART interface	Connected only to the Click Boards connector.
CS/SCK/MOSI/MISO	SPI interface	Connected only to the Click Boards.
SDA/SCL	I2C interface	All I2C sensors
AIN0/AIN1	ADC input interfaces	Grove or click Boards
INT	Hardware Interrupt	Connected only to the Click Boards connector.
RST	Reset	Connected only to the Click Boards connector.
PWM	PWM input	Connected only to the Click Boards connector.
EN	Boost Converter Enable	IO5
IO1/IO3	General purpose I/O	Connected to Grove digital I/O sensors’ connectors.

IO Connector Pin Order

Figure 15 shows the IO connector’s pin order. The connector is located in the bottom layer of the RAK1920 module.

Figure 15: IO connector’s pin order