User manual

MediaTek LinkIt™ Smart 7688 Developer's Guide

Page 63

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import mraa

i2c = mraa.I2c(0)

# Grove - 3-Axis Digital Accelerometer(+-16g)

# is a ADXL345 configured to I2C address 0x53.

i2c.address(0x53)

# The device ID should be

if 0xE5 == i2c.readReg(0x00):

print "Grove - 3-Axis Digital Accelerometer found on I2C Bus"

else:

print "Grove - 3-Axis Digital Accelerometer not found"

For more details on I2C API, please see

here.

To drive an I2C device, you need to operate multiple I2C sequences. LinkIt Smart 7688 also

comes with libUPM pre-installed, which is a set of driver repository built upon libmraa.

Please see

here for a driver example of Seeed Studio 3-Axis Digital Accelerometer.

• SPI

SPI (Serial Peripheral Interface) can also be used to control peripheral devices. On LinkIt

Smart 7688 it consists of 4 pins:

SPI_MOSI(P22), SPI_MISO(P23), SPI_CLK(P24),

and

SPI_CS1(P25).

It’s important to note that the SPI device is also used for communicating with the internal

flash storage on the board. Therefore, developers should access the SPI functionality

through SPI modules only and avoid treating these SPI pins as general GPIO. Otherwise,

the flash storage may work incorrectly.

The SPI module in libmraa is initialized by device index, instead of pin number.

import mraa

spi = mraa.Spi(0)

The SPI protocol allows flexible configurations on signal patterns. Depending on your

peripheral, you may need to configure the pattern with APIs like

bitPerWord and mode.

Please see

here for API details.

Please see MediaTek Labs’ website for tutorials on how to blink the Wi-Fi LED on LinkIt Smart

7688 using mraa in Python and Node.js.

5.1.4. LED blink example using mraa in LinkIt Smart 7688 GPIO in Python

This example shows you how to use mraa library in Python to make the Wi-Fi LED on LinkIt Smart

7688 blink.

1) In LinkIt Smart 7688 SSH system console, create a directory called app and go to that

directory. For example:

mkdir app

cd app