LinkIt Smart 7688

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LinkIt Smart 7688 prduct view.jpg

LinkItTM Smart 7688 (a compact controller board) is an open development board, based on the OpenWrt Linux distribution and MT7688 (datasheet). The board is designed especially for the prototyping of Rich Application IoT devices for Smart-Home[1]. The board offers sufficient memory and storage to enable robust video processing. The platform also offers options to create device applications in Python, Node.js and C programming languages.

[1]This board is only a part of MediaTek LinkItTM Smart 7688 platform which includes other development boards.

Note: This page only guides you to get started with this development board. For a complete guide, please refer to Resources.


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Contents


Features

  • Single input single output (1T1R) Wi-Fi 802.11 b/g/n.
  • Pin-out for GPIO, I2C, I2S, SPI, UART, PWM and Ethernet Port.
  • 580 MHz MIPS CPU.
  • 32MB Flash and 128MB DDR2 RAM.
  • USB host.
  • Micro SD slot.


Application ideas

  • Rich application IoT Devices for Smart-Home
  • Robotics

Specification

Category Feature Specification
MPU Chipset MT7688AN
Core MIPS24KEc
Clock speed 580MHz
Working voltage 3.3V
PCB Size Dimensions 55.7 x 26 mm
Memory Flash 32MB
RAM 128MB DDR2
Power Source USB Power 5V (USB micro-B)
VCC 3.3V (Pin Breakout)
GPIO Pin Count 22 (MT7688AN)
Voltage 3.3V
PWM Pin Count 4 (MT7688AN)
Voltage 3.3V
Max. Resolution 7 bits (customizable)
Maximum Frequency@Resolution

100kHz@1-bit, 50kHz@2-bit, 25kHz@3-bit, 12.5kHz@4-bit, 6.25kHz@5-bit, 3.125kHz@6-bit, 1.5625kHz@7-bit (Standard mode)

40MHz@1-bit, 20MHz@2-bit, 10MHz@3-bit, 5MHz@4-bit, 2.5MHz@5-bit, 1.25Mhz@6-bit, 625kHz@7-bit (Fast mode)

External Interrupts Pin Count 22 (MT7688AN)
SPI Set count 1 (MT7688AN)
Pin numbers P22, P23, P24 (Shared with on-board flash), P25
Max. Speed 25 MHz
SPI Slave Set count 1 (MT7688AN)
Pin numbers P28, P29, P30, P31
Max. Speed 25 MHz
I2S Set count 1 (MT7688AN)
Pin numbers P10, P11, P12, P13
I2C Set count 1
Pin numbers P20, P21
Speed 120K/400K
UART Lite Set count 3 (MT7688AN)
Pin numbers P8, P9, P16, P17, P18, P19
Max. Speed 0.5Mbps
USB Host Set count 1 (MT7688AN)
Pin numbers P6, P7
Speed Micro-AB
ICommunication Wi-Fi 1T1R 802.11 b/g/n (2.4G)
Ethernet 1-port 10/100 FE PHY
Pin numbers P2, P3, P4, P5
User Storage SD Card Micro SD

SDXC

Hardware Overview

Component intro with text 1200.jpg
Back hardware view with text 1200 s.jpg

Parts list

Parts name Quantity
LinkItTM Smart 7688 1PC
Manual 1PC


Getting Started

Connect to the embedded operating system

Note: There are two ways described in the manual. Here, we only show the advanced way (using a USB to Serial adapter) which seems a little harder. But, you will benefit a lot from it in the long run.

Materials required

  • LinkIt Smart 7688 × 1
  • USB cable (type A to micro type-B) × 2
  • USB to Serial adapter× 1
  • Jumper wires × 3

On Windows

1. Install PuTTY. PuTTY provides a system console environment using Secure Socket Shell (SSH) to access the development board's operating system.
2. Install Bonjour Print Service (For Windows 7, Windows 8, Windows 10)
3. Install driver. If you are using a USB cable based on FTDI chip, please download and install its driver from here. If you are having problems with the latest driver, try installing an older version.
4. Next, connect the Serial to USB cable to LinkIt Smart 7688's pins as following table shows:
Pin on USB adapter Corresponding Pin to be connected on LinkIt Smart 7688
Pin RX Pin 8
Pin TX Pin 9
Pin GND Pin GND
LinkIt Smart 7688 demo connection 1200 s.jpg


5. After connecting the Serial to USB cable, open the device manager and notice the COM port number as shown below. This number may vary on different computers.
COM port.jpg
6. Launch the PuTTY terminal and enter the COM port number of the USB device found in the device manager, click on the Serial radio button, type 57600 in Speed box and click Open, as shown below.
Putty configuration.jpg
7. Now you will see printing text as those in a Linux console.

On Mac

1. Install the driver if needed. Check the cable manufacturer's website for driver requirements on Mac and installation instructions.
2. Plug-in the cable and connect the cable to LinkIt Smart 7688.
3. Open a Terminal session.
4. Type ls /dev/cu* in the Terminal. You should see a list of devices. Look for something like cu.usbserial-XXXXXXXX where XXXXXXXX is usually a random identifier. This is the serial device used to access the system console. For example:
  $ls /dev/cu*
 
/dev/cu.Bluetooth-Incoming-Port
 
/dev/cu.Bluetooth-Modem
 
/dev/cu.pablop-WirelessiAP
 
/dev/cu.usbserial-A6YMCQBR
5. Use the screen utility to connect to the serial port and set the baudrate to 57600. This is because the baudrate of the system console is 57600 by default. For example:
$screen /dev/cu.usbserial-XXXXXXXX 57600
6. Now you should be connected to the system console. Press Enter key in the Terminal to bring up the prompt. You will notice that the prompt has become a different regular application, it is the LinkIt Smart 7688 prompt and it looks like the following:
  root@myLinkIt:/#
7. You are ready to make changes to the LinkIt Smart 7688 system through this console.

On Linux

1. Install the driver if needed. Check the cable manufacturer’s website for driver requirements on Linux and installation instructions.
2. Plug-in the cable and connect the cable to LinkIt Smart 7688.
3. Open a Terminal session.
4. Type ls /dev/ttyUSB* in the Terminal. You should see a list of devices. Look for something like cu.usbserial-XXXXXXXX where XXXXXXXX is usually a random identifier. This is the serial device used to access the system console. For example:
$ls /dev/ttyUSB*
/dev/ttyUSB0
5. Use the screen utility to connect to the serial port and set the baudrate to 57600. This is because the baudrate of the system console is 57600 by default. For example:
$sudo screen /dev/ttyUSB0 57600
6. Now you should be connected to the system console. Press ENTER in the Terminal to bring up the prompt. You'll notice that the prompt has become different from your OS X Terminal application, it is the LinkIt Smart 7688 prompt and it looks like the following:
  root@myLinkIt:/#
7. You are ready to make changes to the LinkIt Smart 7688 system through this console.

Running the Blink example

Materials required

  • LinkIt Smart 7688 × 1
  • USB cable (type A to micro type-B) × 1
  • USB to Serial adapter × 1
  • Jumper wires × 3

Get Blink to work

1. Power up your board with a micro-USB cable (only connect the USB Power interface, not the USB Host interface).
Power up.jpg
2. Launch PuTTy and connect to the system with USB to Serial adapter as shown in the previous section.
3. Type python /IoT/examples/blink-gpio44.py and press Enter to run the Blink example.
4. Notice that the Wi-Fi LED blinks steadily.
5. In the system console, type CTRL + C, this will terminate the example.

Connect to the Internet (Switch to Station mode)

There are two Wi-Fi modes, i.e. AP mode and Station mode. Refer this for the differences between them.

1. Power up the board with a micro-USB cable.
2. Open the Wi-Fi connection utility on your computer and connect to the access point named LinkIt_Smart_7688_XXXXXX. XXXXXX is a kind of hardware identifier which varies from board to board.
Connect wifi.jpg
3. Open a browser with URL mylinkit.local/ or 192.168.100.1, set the password for root and sign in. Click Network on the upper right.
Network conf.jpg
4. Select the Station mode and click Refresh or downward arrow on the right to find the AP to connect to. After you have selected the AP, enter password if required. Click Configure & Restart to finish as shown below. Then wait for around 30 seconds to switch mode.
Station mode.jpg
5. Launch PuTTy and connect to the system with USB to Serial adapter as shown in the previous section.
6. Type ifconfig and find the IP address of inet addr as shown below:
IFCONFIG.jpg

Note: It will still enter the Station mode after rebooting the system. Press wi-fi button at least 5 seconds to switch back to AP mode. Note: It will be needed to reboot the embeded OS by using reboot command.

7. Type the IP in a new Tab of browser and you can login to Web user interface to configure the system.
8. Now both the host computer and LinkIt Smart 7688 are connected to internet. Type ping www.mediatek.com in console and you will get:
Ping result.jpg
9. Now you can use internet to configure your system on development board.

Demo: A Hello world example

Note: To avoid running out of memory during native application development, you should set up the native application development environment in a more powerful host environment that enables you to cross-compile the executable format of the LinkIt Smart 7688 target instead. The following table shows an overview of the LinkIt Smart 7688 programming languages and their related development environment on host computer.

Programming language Tools and libraries Applications Host platforms supported
C/C++ Cross compilation toolchain System programming OS X

Linux

Python Python runtime on LinkIt Smart 7688 Prototyping

Network Arduino bridge library

OS X

Linux Windows

Node.js Node.js runtime on LinkIt Smart 7688 Prototyping

Network

OS X

Linux Windows

A Hello world example in Python

1. Use FileZilla and refer to this tutorial to know how to connect with server or another host computer, the server IP (replace host name) address is the inet addr found in Switch to Station mode section, the username is root and password is the password you set in that section.
2. Open a text editor, copy and paste the below example code and save it as helloworld.py.
    print "Hello World!"
3. Copy the file helloworld.py into system on target development environment (LinkIt Smart 7688) with FileZilla, place it under the folder root.
4. Launch PuTTY and connect to system with USB to Serial adapter.
5. Set working directory to /root and enter python helloworld.py to execute.
6. Now you can see Hello World! printed in console.

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