LinkIt Smart 7688 User Manual
Specifications are subject to change without notice.
MediaTek LinkIt™ Smart 7688
User Manual
Version: 0.9 Beta
Release date: October 2015
Unauthorized reproduction of this information in whole or in part is strictly prohibited.
This document contains information that is proprietary to MediaTek Inc.
© 2015, 2016 MediaTek Inc.
Revision
Date
Description
0.9
October 2015
Close Beta
MediaTek LinkIt™ Smart 7688 User Manual
Document Revision History
© 2015, 2016 MediaTek Inc.
Page 1 of 38
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MT7688AN SOC Specifications
CPU
MIPS24KEc (580 MHz)
Total DMIPs
580 x 1.6 DMIPs
I-Cache, D-Cache
64 KB, 32 KB
L2 Cache
N/A
• DDR1/DDR2
• Max. 2 Gb, 193 MHz
• 3B addr mode (max
512Mbit)
SD
SD-XC (class 10)
RF
1T1R 802.11n 2.4GHz
Package
DR-QFN156-12 mm x 12 mm
MediaTek LinkIt™ Smart 7688 User Manual
1. Introduction
LinkIt Smart 7688 development platform is an IoT development platform by
MediaTek Labs. It enables you to design and create Wi-Fi connected devices
for the home, the office and Cloud applications.
1.1. What is MediaTek LinkIt Smart 7688 Development
Platform
The LinkIt Smart 7688 is an open development platform based on Linux
distribution OpenWrt
hardware configurations: LinkIt Smart 7688 (MPU only) and LinkIt Smart 7688
Duo (MPU and MCU). The LinkIt Smart 7688 is powered by MediaTek’s MT7688
SOC and supports Windows, Mac OS X and Linux.
LinkIt Smart 7688 Duo has the same MPU in addition to a MCU which is
powered by ATmega32U4. It supports Arduino and high level programming
language such as Python, Node.js and C so that you can create your own
scripts for rich peripheral interactions.
. It offers two development boards which come in two
The LinkIt Smart 7688 development platform supports built-in Wi-Fi,
Ethernet, USB host and Micro-SD card slot as well as serial port for Linux
console.
1.2. MediaTek MT7688AN Chip Specification Summary
Specifications of the MT7688AN SOC are shown in below.
Memory
SPI Flash
• 16 bits
128Mbit)
• 4B addr mode (max
PCIe 1
USB 2.0 1
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Interface Count
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Page 2 of 38
Interface Count
Fast Ethernet Switch 5
I2S 1
PCM 1
PWM 4
SPI 1
I2C 1
UART(Lite) 3
JTAG 1
Table 1 MT7688AN SOC Specification
1.3. LinkIt Smart 7688
MediaTek LinkIt™ Smart 7688 User Manual
LinkIt Smart 7688 is one of the most highly integrated and compact hardware
development boards available for IoT prototyping.
1.3.1. Key Features
LinkIt Smart 7688’s key features include the following:
• Wi-Fi 802.11 b/g/n (2.4G)
• 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
LinkIt Smart 7688 is shown in Figure 1.
© 2015, 2016 MediaTek Inc.
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Page 3 of 38
data will be
MediaTek LinkIt™ Smart 7688 User Manual
Figure 1 LinkIt Smart 7688 development board (MPU only)
1.3.2. Buttons
The buttons description on LinkIt Smart 7688 and how to use them are
described in Table 2.
Scenario Button Action
Resets the MPU MPU Reset Button One Press
Resets Wi-Fi to
AP mode
Factory resets
and enters AP
mode
WARNING:
Restore to
default setting
and all user
Wi-Fi Reset
Button
(After system is
boot up)
Wi-Fi Reset
Button
(After system is
boot up)
Press for at
least 5 seconds
and release
Press for at
least 20 seconds
and release
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removed from
Mode
Status
LED blink pattern
3 blinks in 1 second
Without client
Disconnected
Off
Connecting
2 blinks in 1 second
Blinking based on
Scenario Button Action
the device
MediaTek LinkIt™ Smart 7688 User Manual
Upgrades
firmware from a
USB drive
Upgrades boot
loader from a
USB drive
WARNING:
Restore to
default setting
and all user
data will be
removed from
the device
Table 2LinkIt Smart 7688 Development board buttons
Wi-Fi Reset
Button (At power
up)
Wi-Fi Reset
Button (At power
up)
Press for at
least 5 seconds
and release
Press for at
least 20 seconds
and release
1.3.3. LEDs
• Power
Power LED turns solid on in green color when power is supplied.
• Wi-Fi
Wi-Fi LED are in orange color and their blink pattern is described in Table
3.For more information on Access Point and Station mode, please see 2.3,
“Network Environment”.
With client
device
AP Mode
device
Station
Mode
Data
transmission
Table 3 Wi-Fi LED blink pattern in LinkIt Smart 7688 HDK
and pause for 0.5
seconds (cycle
repeats)
Off
the transmitted data
package
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Page 5 of 38
Approximate Power
Peak
475.3 mA
Average
255.6 mA
Device boot up
Peak
605.4 mA
MediaTek LinkIt™ Smart 7688 User Manual
1.3.4. Antenna
There are two types of antenna support available on LinkIt Smart 7688
development board:
1) Built in Wi-Fi chip antenna and it is the default antenna.
2) I-PEX connector for external antenna.
To enable the connector, you’ll need to remove the resistor R233 located on
the top left corner of the I-PEX connector, as circled in Figure 2.
Figure 2 Removing the resistor to enable I-PEX connector
1.3.5. USB Host
LinkIt Smart 7688 provides USB host capability which enables it to connect
to different USB devices such as webcams, USB drives, keyboards, joysticks
and more. The connector used is USB Micro-AB type.
1.3.6. USB Power
The USB cable provides 5V steady power source to LinkIt Smart 7688
development boards. When you add peripheral devices such as SD card, USB
drive or other USB devices to the development board, additional power may
be consumed. Please use a proper USB cable to reduce power loss. If your
peripheral device consumes power heavily, it’s better to use an external
power source for it.
The approximate power consumption of various devices used on LinkIt Smart
7688 is described in below.
Scenario
Consumption
To establish WiFi connection
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Page 6 of 38
Approximate Power
Average
195.1 mA
Downloading file
Peak
540.4 mA
Average
275.8 mA
Downloading a
Peak
569.5 mA
Average
304.9 mA
Downloading a
Peak
522.4 mA
Average
271.3 mA
MediaTek LinkIt™ Smart 7688 User Manual
Scenario
Consumption
to a SD Card via
Wi-Fi
file to a USB
Drive via Wi-Fi
file to flash
via Wi-Fi
Table 4 Peripherals Power Consumption
1.3.7. Accessories
LinkIt Smart 7688’s standard package comes with the development board only.
You will need additional accessories for different purposes as described
below.
1) USB Power Cable (Required): You’ll need a USB type A to
Micro-B plug cable to power the LinkIt Smart 7688
development board from a PC or other USB powered source.
2) Micro USB OTG (On-The-Go) or Host Cable (Optional): Use this
OTG cable to access Type A USB devices such as USB drive or
USB camera and more as shown in Figure 3.
Figure 3 USB OTG cable
3) USB-UART Cable (Optional): Use this cable to communicate to
Linux console.
4) Micro SD Card (Optional): Use Micro SD card for extra
storage space for applications and data.
5) USB Drive (Optional): For extra storage. You can also use it
to store bootloader and firmware to upgrade LinkIt Smart
7688.
Unauthorized reproduction or disclosure of this information in whole or in part is strictly prohibited.
© 2015, 2016 MediaTek Inc.
This document contains information that is proprietary to MediaTek Inc.
Page 7 of 38
MediaTek LinkIt™ Smart 7688 User Manual
1.3.8. Breakout Board (TBD)
1.3.9. JTAG
You can use JTAG interface to debug MT7688AN. To access JTAG interface, you
will need to unsolder resistor R95 and solder it to resistor R3 on the
7688 development board. After you’ve moved the resistor and reboot the
device you’ll activate JTAG function. The steps are:
1) Find a group of resistors on the bottom side of LinkIt Smart
7688 (top-right view) as circled in below.
Figure 4 JTAG resistors on LinkIt Smart 7688 Bottom view
2) Next, you will move a resistor by unsoldering and soldering
it to a lower position as shown in below, after you’ve
finished moving the resistor, restart the device and you
should be able to activate JTAG function.
Figure 5 Moving a resistor to access JTAG mode
© 2015, 2016 MediaTek Inc.
This document contains information that is proprietary to MediaTek Inc.
Unauthorized reproduction or disclosure of this information in whole or in part is strictly prohibited.
Page 8 of 38
LinkIt Smart 7688
Chipset
MT7688AN
Core
MIPS24KEc
Clock speed
580MHz
Working voltage
3.3V
PCB Size
Dimensions
55.7 x 26 mm
Flash
32MB
RAM
128MB DDR2
USB Power
5V (USB Micro-B)
3.3V (Pin
Pin Count
22 (MT7688AN)
Voltage
3.3v
Pin Count
4 (MT7688AN)
Voltage
3.3v
7 bits
External
MediaTek LinkIt™ Smart 7688 User Manual
1.3.10. Specifications
The key specifications of LinkIt Smart 7688 development boards are shown
inTable 5.
Category Feature
MPU
Memory
Power Source
VCC
GPIO
Spec.
Breakout)
PWM
Interrupts
SPI
Max. Resolution
(customizable)
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
Maximum
(Standard mode)
Frequency@Resoluti
on
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)
Pin Count 22 (MT7688AN)
Set count 1 (MT7688AN)
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Page 9 of 38
LinkIt Smart 7688
• P22, P23,P24
Max. Speed
25 MHz
P28, P29, P30,
Max. Speed
25 MHz
Set Count
1 (MT7688AN)
P10, P11, P12,
Set Count
1
Pin numbers
P20, P21
Speed
120K/400K
Pin Count
1 (MT7688AN)
Pin numbers
P6, P7
Connector type
Micro-AB
1T1R 802.11 b/g/n
1-port 10/100 FE
Pin numbers
P2, P3, P4, P5
Micro SD
MediaTek LinkIt™ Smart 7688 User Manual
Category Feature
Pin numbers
Set count 1 (MT7688AN)
SPI Slave
Pin numbers
I2S
Pin numbers
I2C
Spec.
(Shared with
on-board
flash)
• P25
P31
P13
Set Count
UART (Lite)
Pin numbers
Max. Speed 115,200 bps
USB Host
Wi-Fi
Communicatio
n
Ethernet
User Storage SD Card
3 (MT7688AN)
P8, P9, P16, P17,
P18, P19
(2.4G)
PHY
SDXC
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Table 5 LinkIt Smart 7688 development boards specifications
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Page 10 of 38
MediaTek LinkIt™ Smart 7688 User Manual
1.3.11. Pin-out Diagram
This pin-out diagram helps you to map the pins on LinkIt Smart 7688
development board to the peripheral devices you want to attach through
interfaces such as GPIO, PWM, I2C, I2S, SPI, UART and more. The available
pins for LinkIt Smart 7688 HDK are illustrated in the next page. You can
also download it from MediaTek Labs website.
© 2015, 2016 MediaTek Inc.
Page 11 of 38
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