LED cube demo for Linkit Smart 7688 board

Hardware:

• LinkIt Smart 7688 board,
• LED cube 8x8x8, and
• simple vibration sensor module.

Software:

• MRAA library adapted for Linkit Smart 7688 platform,
• Debian Linux installed over the factory OpenWRT system of the Linkit Smart 7688 board.

The demo program is written in C, with usage of MRAA library - an emerging standard for a low level access to IoT hardware resources from the Linux application. The demot displays a few different animations in a loop. A user can tap the sensor to skip the current animation and jump to next one.

Connection

The cube is connected to the Linkit Smart 7688 board, pins P10, P11, P13, P25-P30. Sensor output is attached to the pin P21.

Cube	Signal	Linkit	MRAA
P1/1	+5V	5V	---
P1/2	Y0	P10	gpio2
P1/3	Y1	P11	gpio3
P1/4	Y2	P13	gpio1
P1/5	Y3	P25	gpio6
P1/6	Y4	P26	gpio18
P1/7	SDI	P27	gpio19
P1/8	CLK	P28	gpio17
P1/9	/LE	P29	gpio16
P1/10	/OE	P30	gpio15
P1/11	EXT	P31	gpio14
P1/12	GND	GND	---
---	Sensor	P21	gpio4

Connection to the Linkit board:

            Linkit
        |              |
        |           P21|-- sensor
        |              |
        |              |
  gnd --|GND           |
        |           P25|-- y3
        |           P26|-- y4
  +5v --|5V         P27|-- sdi
   y0 --|P10        P28|-- clk
   y1 --|P11        P29|-- /le
        |           P30|-- /oe
   y2 --|P13        P31|-- ext
        ----------------

Connection to the Cube board:

       Cube
         ------
         |
    GND--|12 - Ground
    EXT--|11 - LED current control
    /OE--|10 - Output enable \
    /LE--| 9 - Latch enable  | shift registers
    CLK--| 8 - Clock         |
    SDI--| 7 - Serial data   /
    Y4 --| 6 - Lower backlight
    Y3 --| 5 - Upper backlight
    Y2 --| 4 \
    Y1 --| 3 | Layer select
    Y0 --| 2 /
    +5V--| 1 - Power
         |
         -------

Schematics and docs:

• Pinout of the Linkit Smart 7688 board
• Schematic of the Cube board
• Picture of the Cube board
• MRAA pin mappings for the Linkit Smart 7688 board