Titel	Autor	Date
###Title###	Jakob Klepp	2015-01-14

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I2C & ADXL345

Erstellen Sie ein Projekt, wo der ADXL345 über den I2C-Bus die Informationen an den uC sendet. Geben Sie diese drei Achsen auf der seriellen Schnittstelle (UART) zur Kontrolle aus.

facts to ADX345

Fact name	Value	Source
com.Address:	0x53	p.18
Power-Mode Register:	0x2d	p.23
Power_modi:	see config on	p.25
x-Axis:	0x32, 0x33	p.23
y-Axis:	0x34, 0x35	p.23
z-Axis:	0x36, 0x37	p.23

x-Axis, y-Axis, z-Axis: 8-bit/register, necessary to join those two value to one 16-bit value. Use bitshifting!

Be aware, this is raw-Data => convert to floating point info through multiplication!

Tasks

1. Define usefull commands in a Header-File. Stick to the order defined by the library functions.

   read Process: I2CMasterSlaveAddrSet(..., ..., false)
                 I2CMasterDataPut
                 i2CMasterControl
                 while (I2CMasterBusy(...))
                 I2CMasterSlaveAddrSet(..., ..., true)
                 I2CMasterControl(..., ...)
                 while(I2CMasterBusy(...))
                 I2CMasterDataGet(...)

   write process is similar to read process

   => check chapter 17 in FW-Datasheet (TivaWare Peripherial Driver Library User Guide)

   -- - - -

   SW-TM4C-DRL-UG [2]

TivaWare .c files needed

driverlib

• gpio.c
• i2c.c
• sysctl.c
• uart.c

utils

• uartstdio.c

API

adxl345.h

int8_t ReadI2C(uint16_t, uint16_t)

Read a byte of data from given device address and register

Arguments:

• device_address
• device_register

Returns:

Byte read from the specified register.

void WriteI2C(uint16_t, uint16_t, int8_t)

Write a byte of data to given device address and register

Arguments:

• device_address
• device_register
• device_data

void InitI2C(void)

This function sets up I2C0 to be used for communicating with the accelerometer.

void I2C_checkError(void)

Check if there was an I2C error. Write it to UART if there was one.

void ADXL_SetPowerMode(uint8_t)

Set the power mode of the accelerometer.

Arguments:

• powerMode

int16_t ADXL_getAcceleration_rawX(void)

Reads the raw acceleration of the x axis from the adxl345.

Returns:

"Raw" Acceleration data.

int16_t ADXL_getAcceleration_rawY(void)

Reads the raw acceleration of the y axis from the adxl345.

Returns:

"Raw" Acceleration data.

int16_t ADXL_getAcceleration_rawZ(void)

Reads the raw acceleration of the z axis from the adxl345.

Returns:

"Raw" Acceleration data.

int32_t ADXL_getAcceleration_X(void)

Reads the decoded acceleration of the x axis from the adxl345.

Returns:

Acceleration data.

int32_t ADXL_getAcceleration_Y(void)

Reads the decoded acceleration of the y axis from the adxl345.

Returns:

Acceleration data.

int32_t ADXL_getAcceleration_Z(void)

Reads the decoded acceleration of the z axis from the adxl345.

Returns:

Acceleration data.

Deployment & Testing

The project can be build with make all and flashed to the device with make flash.

Pins

Launchpad	ADXL345
+3.3V	VCC
+3.3V	CS
GND	GND
PB3	SDA
PB2	SD0

SDA and SD0 are connected to GND with resistors.

Output

The output looks like this:

Each time a new value is printed to the command line the old one will be overwritten, no scrolling. The unit of these values is mg.

Source

[1] ADXL345.pdf,

http://www.analog.com/static/imported-files/data_sheets/ADXL345.pdf, last viewed: 2015-01-14

[2] TivaWare™ Peripheral Driver Library,

http://www.ti.com/lit/ug/spmu298a/spmu298a.pdf, last viewed: 2015-01-14

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