Sparkfun MG2639 Cellular Shield Technical document

MG2639 Cellular Shield Hookup Guide





Introduction

The MG2639 Cellular Shield is a perfect addition to any Arduino project that

requires connectivity when there’s no WiFi signal radiating or Ethernet drop

nearby. The ZTE MG2639 module, which this shield is built around,

supports SMS, TCP, UDP, and can even be used to make or receive phone

calls (imagine that!). That means you can send and receive text messages,

or use it to remotely connect your Arduino to the Internet. To top it off, it has

an integrated GPS receiver, so it doesn’t get lost.

The MG2639 Cellular Shield is the perfect centerpiece for any remotely-

operating project – whether it’s a text-message-triggered MP3 player, an

environmental monitor logging to data.sparkfun.com, or a new iteration of

the Port-O-Rotary telephone.

Covered In This Tutorial

This tutorial aims to answer any and every question you have about the

MG2639 Cellular Shield. In the beginning, we’ll focus on the hardware of

the board – looking at the schematic, pin-outs, and jumpers on-board. Then

we’ll discuss what assembly steps to take before connecting the shield to

your Arduino – finding the right power supply, plugging in a SIM card, and

so on. Finally we’ll show off the MG2639 Arduino library and document a

series examples that demonstrate how to use the module’s TCP, SMS, and

phone functionalities.

This tutorial is split into sections. Click the links to the right if you want to

jump around to other sections.

Page 1 of 2

Required Material

Aside from the MG2639 Cellular Shield itself, there are a few extra

components you’ll need to connect it all up. Here’s a list of recommended

products which we will use in this guide:

• SparkFun RedBoard – You’ll need a “brain” to control the cellular

shield. It should work with any Arduino board with the “standard”

footprint – Arduino Uno, Arduino Leonardo, Arduino Pro, etc.

• Stackable Headers – Solder these to you shield so it can connect to

your Arduino.

• Cellular Antenna – For the MG2639 to connect to a network, it needs

an external antenna.

• SMA to U.FL Adapter – The MG2639 only has U.FL antenna ports,

so if your antenna has an SMA connector (like the one above) you’ll

need an adapter.

• 9V Power Adapter – The MG2639 Shield requires more power than

an Arduino can supply when it’s powered over USB. We recommend

this 9V wall adapter, but any power supply within your Arduino’s

specified input voltage range should work.

• SIM Card – You’ll need access to a cellular provider’s network. Any

activated, full-size SIM card should work. You should be able to buy

any “burner” phone and yank out the SIM card.

Beyond those items, here are some optional components you may want to

add as well:

•GPS Antenna – If you want to take advantage of the MG2639’s GPS

features, you’ll need to connect a second antenna rated for GPS

signals. We’re working on sourcing a good, U.FL antenna for the

MG2639. In the meantime, we’ve had success with the this Tagolas

GPS antenna.

SparkFun RedBoard -

Programmed with Arduin



DEV-12757



60

Arduino Stackable Header

Kit - R3

PRT-11417

10

Wall Adapter Power Supply -

9VDC 650mA



TOL-00298



3

Quad-band Cellular Duck

Antenna SMA

CEL-00675

Page 2 of 2

• 12mm Coin Cell Battery – The shield includes a socket for a 12mm

coin cell battery – used by the on-board GPS module to retain

location memory and enable faster location fixes.

• Speaker and Microphone – If you want to turn the MG2639 Shield

into an actual cell phone these become pretty important.

Suggested Reading

Before delving into this guide, there are a few subjects you should be

familiar with. Here are some tutorials you may want to check out before

continuing on:

• Serial Communication – Both the cellular and GPS modules

communicate with your Arduino over a serial UART.

• Arduino Shields – Explore all things Arduino Shields. What they are

and how to assemble them.

• Installing an Arduino Library – We’ve written an Arduino library for

this shield, if you’ve never installed a library before, check this guide

out.

Hardware Overview

Before you get to connecting the MG2639 Cellular Shield to your Arduino,

you should familiarize yourself with the features and abilities of the board.

This page serves as an overview of the shield’s components and pin-outs.

It also looks at some of the “hidden” features of the board.

Component Overview

For a quick overview, here are most of the components of interest on the

shield:

Arduino Pins Used

One of the most important characteristics of a shield are the Arduino pins

used, here’s a list of the pins used by the cellular shield:

Arduino

MG2639

Function

Notes

VIN Power

Supply

The MG2639 requires that the Arduino be

supplied with an external power source (USB

won't cut it). This pin is disconnectable via a

jumper.

A0 RING Alert This pin will go low when a phone call is

coming in.

2CellUART

Cell module's data output (4800 baud).

Page 3 of 2

3CellUART

Cell module's data receive (4800 baud).

7 Cell boot

This pin has the same control over the module

as the BOOT button (explained below).

8 GPS UART

GPS module's data output (115200 baud).

9 GPS UART

GPS module's data receive.

Cell and GPS UARTs

Communication with the cellular and GPS module’s occurs on two separate

serial UARTs. To leave the Arduino’s hardware UART free for debugging

and uploading sketches, both UARTs are broken out to digital pins –

intended for use with the SoftwareSerial library.

Because the SoftwareSerial library can’t reliably support high-ish baud

rates, we’ve intentionally slowed down the MG2639’s cellular UART to 4800

bps, rather than the module’s default bit rate of 115200. This slower rate

ensure data reliability, and gives the Arduino some extra time to process

large strings.

The GPS UART is hard-coded to 115200 baud, which make it harder to

use with SoftwareSerial. Instead, we recommend using the AltSoftSerial

library with this part of the module.

Either of the two UARTS (the cell or GPS) can be switched over to the

Arduino’s hardware UART. Check out the “Jumpers” section below for more

information.

LED Status Indicators

There are a trio of LEDs on the MG2639 Cellular Shield which indicate

connectivity or power status:

•POWER – This red LED is connected to the MG2639 module’s

power supply line. If this LED is on, the module is receiving power.

•RSSI – This green LED indicates the status of your cellular network.

It’ll blink at various rates to show what state it’s in:

◦OFF – The module is powering on (assuming it has power).

◦1 Hz blink – Module is idle.

◦3 Hz blink – Searching for a network.

◦5 Hz blink – Module is in a traffic state (a phone call or data

transmission).

•GPS – GPS fix indicator. This yellow LED will illuminate when the

MG2639’s GPS module gets a solid fix.

Boot & Reset Buttons

Two buttons labeled “BOOT” and “RESET” are built into the shield. The

“RESET” button is simply the Arduino reset, it’ll have no direct effect on the

MG2639.

Page 4 of 2

The “BOOT” button connects to the MG2639’s PWRKEY input, which turns

the module on or off. This button works exactly as you might expect any cell

phone power button to work. If the module is off, hold the button down for

2-5 seconds then release to turn it on. If the module is on and you hold the

button down and release, it’ll turn off.

Control of this button is shared between the physical button itself and

Arduino pin 7. The Arduino pulling pin 7 LOW has the same effect as

pushing the button down. This gives the Arduino machine control over the

module’s ON/OFF status.

Bottom-Side Jumpers

To keep the Shield as multi-purpose as possible, there are a number of

jumpers on the backside that can be used to switch the interface pins or

power supply.

To open any of these jumpers, use a hobby knife, and remove the small

trace between any two connected pads. To connect a jumper, solder a

small solder joint between two pads.

Here’s a quick rundown of each jumper:

•VDDIO – This jumper selects the voltage for logic running into the

high side of the shield’s TXB0104 level shifter. It defaults to 5V but

can be switched to 3.3V if your application requires.

•Cellular UART RX and TX – These jumpers allow you to switch the

cellular module’s RX and TX between either pins 2 and 3 or 0 and 1.

That means selecting between a software (2/3) or hardware (0/1)

UART.

•GPS_TX and GPS_RX – Like the other UART jumpers, these allow

you to set the GPS module’s UART to either software (8/9) or

hardware (1/0).

•VGPS Disable (SJ4) – This jumper controls power delivery to the

shield’s GPS module. If you don’t want to use the MG2639’s GPS

module, and want to avoid the power loss it incurs, cut this jumper.

•VBAT Enable/Disable (SJ2 and SJ3) – If you want to power the

Cellular Shield from a single-cell lithium polymer battery, you’ll need

to attack both of these jumpers. Shorting SJ3 will connect the JST-

footprint connector directly to the module’s power supply. Opening

SJ2 will disconnect the voltage regulator output from the rest of the

circuit.

•FTDI Power Enable (SJ8) – If you want to use an FTDI Basic to

troubleshoot the MG2639’s UART, this jumper will allow you to power

the VDDIO line with the FTDI’s VCC pin.

•BOOT Control – This jumper allows you to remove Arduino pin 7

(mislabeled “6” near the jumper) from the MG2639’s boot button.

Page 5 of 2

Note: If you decide to use the hardware UART, make sure to only connect

one of the two modules to the 0/1 pins! If both are connected, bus

contention and data loss will occur.

Hardware Assembly

Now that you’re familiar with the components and inner workings of the

MG2639 Cellular Shield, it’s time for some assembly!

Soldering

You’ll need to solder a header of some kind to the shield, in order to

connect it to your Arduino. Stackable headers are always a popular option

as they allow you to plug additional shields or jumper wires into your

Arduino’s unused pins.

You can also instead use male headers to connect it to the Arduino. If

you’re looking to use the shield as more of a breakout board, you can

solder wires directly to the pins you need.

For more help with shield assembly, check out our Shield Assembly Guide.

Antennae

Both the cellular and GPS functions of the MG2639 require an external

antenna connected to the module. There are two U.FL connectors on the

side of the chip – one labled “GSM” the other “GPS.”

Any of the quad-band cellular antennas below will work with the shield, but

you’ll need a U.FL to SMA adapter to complete the connection.

Quad-band Cellular Duck

ntenna SMA



CEL-00675

Quad-band Wired Cellular

Antenna SMA

CEL-00290

Quad-band Cellular Antenna

Page 6 of 2

Snapping these U.FL connectors can be tricky! Carefully line up the

little head of the connector with the "GSM" or "GPS" label, then press

down with your thumb or finger. It can be difficult to get enough force

from your finger, so once you have good alignment you may want to

use the blunt, rounded end of the cell antenna to snap the connector

in place.

We’re working on sourcing a good antenna for the MG2639. We’ve had

success with this patch antenna from Tagolas.

SIM Card

One of the hardest parts in getting the shield to work is finding a suitable

network and SIM card to run it on. You may be able to find a sweet,

contract-free deal like our T-Mobile 6-month Unlimited card.

Another option is to pick up a prepaid “burner” phone – like a Go phone –

and swap the SIM card into the shield.

The workings of the SIM card socket can take some getting used to. To

unlock the latch, push the top part of the assembly towards the battery,

then lift it up. Slide the SIM card into the moving part of the socket with the

SIM’s notch pointing away from the battery holder.

Then fold the arm back into the body of the socket, and gently push it

forward towards the “LOCK” position.

Connecting a Speaker and Microphone

To use the MG2639 as a cell phone, you’ll need to add some external bits

of hardware. The audio port, on the end of the shield, allows you to hook up

a speaker and microphone directly to the MG2639’s audio interface. The

audio port has six pins broken out for speaker, earpiece, and/or microphone

hardware. These pins are labeled:

•EAR_SPK – “Earpiece” speaker. This is a single-ended audio output

with 32 Ωimpedance. If using this interface, the other pin of the

speaker should be connected to ground.

SMA



CEL-08347



2

Page 7 of 2

•SPK+ and SPK- – Differential speaker interface. If using this

interface, the two pins of a speaker can be tied directly to these two

pins.

•EAR_MIC – “Earpiece” microphone. This is a single-ended audio

input. If you use this interface, connect the other microphone pin to

ground.

•MIC+ and MIC- – Differential microphone input. If you’re using this

interface the two microphone pins can be connected directly to these

pins.

There are a variety of speakers and microphones that can be connected to

these pins. If you just want to try a simple proof-of-concept, you can use our

Electret Microphone and Thin Speaker to test the interface out.

Section 4.4 of the MG2639 Hardware Development Guide includes some

excellent information about connecting an audio interface to the MG2639.

Consult that document for more information about the impedances, offset

voltages, and sensitivities.

Supplying Power

Beyond finding a suitable SIM card, the most important part of getting the

MG2639 Shield working is supplying it with enough power.

Power Supply Requirements

Depending on which state it’s in, the MG2639 module can be a relatively

power-hungry device. The maximum current draw of the shield is around

350mA. It usually won’t pull that much, but may require around 260mA

during phone calls or 80mA during network transmissions. This chart from

the datasheet summarizes what you may expect:

In selecting your power supply, it’s important to note that the MG2639

Shield will not work if your Arduino is only powered off USB – an external

power supply is required to power both the Arduino and Shield. The

shield includes a 3.8V regulator to supply the MG2639 within its 3.4-4.2V

range. That regulator is sourced by the Arduino’s VIN pin. We recommend

a barrel jack power supply with a voltage output in the acceptable range of

your Arduino (or at least 4.5V for the shield).

Our 9V power supply is a good choice, and the one we used in our

prototyping and testing.

(Optional) Using a Battery Supply

Page 8 of 2

The operating voltage range of the MG2639 (3.4-4.2V) makes it an ideal

candidate for direct LiPo battery supply. The Shield can be powered

through a LiPo battery, but there are some adjustments you’ll need to make

to the bottom-side jumpers before doing so.

As a starting point, here is the schematic of the shield’s voltage regulator

and power input circuitry:

In order to power off a battery instead of the Arduino’s VIN pin (“VRAW” on

the schematic), you need to cut SJ2 and short SJ3.

Jumper configuration for battery power. Cut SJ2, and short SJ3 (then clean

it up better than we did).

SJ2 will prevent the 3.8V regulator from supplying a competing voltage to

the battery. SJ3 will allow the battery to directly supply the MG2639.

To connect the battery to the shield, two connectors are broken out on the

top side of the board, labeled “BATT”. One connector is a footprint for our

2-Pin JST Connectors, which mates with our catalog of single-cell LiPo’s.

The other is a simple 0.1" 2-pin header.

LiPo batteries are a perfect power supply for the LiPo shield. Even better

when paired with a LiPo Charger Basic.

Page 9 of 2

The battery supply will not be fed back into the Arduino, so you’ll need to

either find a separate power supply for the microcontroller board, or split the

battery in two directions.

Installing and Using the Arduino Library

Now that all of the nitty-gritty hardware stuff is out of the way, it’s time to get

to some Arduino coding! First, we’ll get you set up with the

SFE_MG2639_CellularShield library, then we’ll delve into some example

sketches.

Update Arduino! For the SFE_MG2639_CellularShield library to

function properly, you'll need to be using an updated version of

Arduino. Arduino 1.6.1 or above is required. Download the latest

version of the IDE from arduino.cc.

(That release of Arduino included an improved version of the

SoftwareSerial library, which the Cellular Shield library depends on.)

Download and Install the Arduino Library

We’ve written an Arduino library specifically for the MG2639 Cellular Shield.

Click the button below to download it, or clone it from our GitHub repository.

DOWNLOAD THE SFE_MG2639_CELLSHIELD LIBRARY

For help installing the library, please check out our Installing an Arduino

Library tutorial. You’ll need to copy the library into a “libraries” folder within

your Arduino sketchbook.

Try the MG2639_GetInfo Example

To prove that your cellular shield is working, try running the most simple

example sketch included with the library. MG2639_GetInfo.ino is a simple

sketch that turns the shield on, verifies communication with it, and prints all

sorts of information like your CIMI, ICCID, and phone number.

Open the sketch by going to File > Examples > SparkFun MG2639

CellShield > MG2639_GetInfo.

Then, after verifying that your SIM card, antennas, and power supply are all

connected, upload the sketch.

Page 10 of 2

Table of contents

Other sparkfun Microcontroller manuals

sparkfun

sparkfun Binary Blaster Series User manual

sparkfun

sparkfun ESP8266 Technical document

sparkfun

sparkfun micro climate Kit User manual

sparkfun

sparkfun DEV-14591 User manual

sparkfun

sparkfun Ardumoto Kit Technical document

sparkfun

sparkfun MaKey MaKey User manual

sparkfun

sparkfun nRF9160 Thing Plus Technical document

sparkfun

sparkfun QwiicBus COM-18000 Technical document

sparkfun

sparkfun Tinker Kit User manual

sparkfun

sparkfun DA16200 Technical document

sparkfun

sparkfun BrickPi User manual

sparkfun

sparkfun QuickLogic Thing Plus Technical document

sparkfun

sparkfun Decade Resistance Box Technical document

sparkfun

sparkfun MicroMod SEN-16794 Technical document

sparkfun

sparkfun Roshamglo Badge Kit Technical document

sparkfun

sparkfun Simon Tilts Series User manual

sparkfun

sparkfun RFID Starter Kit Technical document

sparkfun

sparkfun Qwiic GPIO Technical document

sparkfun

sparkfun Gram Piano Series User manual

sparkfun

sparkfun Qwiic Pro Micro USB-C Technical document

sparkfun

sparkfun Simon 10547 User manual

Popular Microcontroller manuals by other brands

AMS

AMS AS7261 Demo Kit user guide

Novatek

Novatek NT6861 manual

Espressif Systems

Espressif Systems ESP8266 SDK AT Instruction Set

Nuvoton

Nuvoton ISD61S00 ChipCorder Design guide

STMicrolectronics

STMicrolectronics ST7 Assembler Linker user manual

Texas Instruments

Texas Instruments Chipcon CC2420DK user manual

Lantronix

Lantronix Intrinsyc Open-Q 865XR SOM user guide

NEC

NEC 78GK0S/K 1+ Series Application note

Mikroe

Mikroe SEMITECH N-PLC Click Application note

Intel

Intel Agilex user guide

Cypress

Cypress CY4607 HX2VL quick start guide

DIGITAL-LOGIC

DIGITAL-LOGIC MICROSPACE manual

Texas Instruments

Texas Instruments TMS320F2837 D Series Workshop Guide and Lab Manual

CYPRES

CYPRES CY14NVSRAMKIT-001 user guide

Texas Instruments

Texas Instruments INA-DUAL-2AMP-EVM user guide

Espressif Systems

Espressif Systems ESP8266EX Programming guide

Abov

Abov AC33M8128L user manual

Laird

Laird BL654PA user guide

sparkfun MG2639 Cellular Shield Technical document

Popular Microcontroller manuals by other brands