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MSP430G2553 launchpad and
MPU6050 Introduction
----Liqiang Du(EE MS)
MSP430 figure
MSP430 pin figure
MPU6050 module
VCC and GND for power
supply:3-5v
SCL and SDA for I2C
communication with MSP430
XCL and XDA to connect
magnetic sensor
USCI I2C Mode
Figure : I2C Bus Connection Diagram
The two pull up resistor is necessary for I2C mode to work properly
I2C data transfer
Figure : I2C Module Data Transfer
The first byte after a START condition consists of a 7-bit
slave address and the R/W bit. When R/W = 0, the
master transmits data to a slave. When R/W = 1, the
master receives data from a slave. The ACK bit is sent
from the receiver after each byte on the 9th SCL clock.
I2C initialization code
void Init_i2c(uint8_t devAddr)
{
UCB0CTL1 |= UCSWRST; // Enable SW reset
UCB0CTL0 = UCMST + UCMODE_3 + UCSYNC; // I2C Master, synchronous mode
UCB0CTL1 = UCSSEL_2 + UCSWRST; // Use SMCLK, keep SW reset
UCB0BR0 = 10; // fSCL = 1Mhz/10 = ~100kHz
UCB0BR1 = 0;
P1SEL = BIT6 + BIT7; // Assign I2C pins to USCI_B0
P1SEL2 = BIT6 + BIT7; // Assign I2C pins to USCI_B0
UCB0I2CSA = devAddr; // Slave Address is 069h
UCB0CTL1 &= ~UCSWRST; // **Initialize USCI state machine**
IE2 |= UCB0RXIE + UCB0TXIE; // Enable RX and TX interrupt
}
I2C Module Operating Modes
Transmitter
Master
Receiver
I2C
Transmitter
Slave
Receiver
USCI UART Mode
In asynchronous mode, the USCI_Ax modules connect the MSP430 to an
external system via two external pins, UCAxRXD and UCAxTXD. UART mode
is selected when the UCSYNC bit is cleared.
In UART mode, the USCI transmits and receives characters at a bit rate
asynchronous to another device. Timing for each character is based on the
selected baud rate of the USCI. The transmit and receive functions use the
same baud rate frequency.
UART initialization code
void initUart(void)
{
UCA0CTL1 |= UCSSEL_2;
// Use SMCLK
UCA0BR0 = 104;
// 1MHz 9600
UCA0BR1 = 0;
// 1MHz 9600
UCA0MCTL = UCBRS0;
// Modulation UCBRSx = 1
P1SEL = BIT1 + BIT2 ;
// P1.1 = RXD, P1.2=TXD
P1SEL2 = BIT1 + BIT2 ;
// P1.1 = RXD, P1.2=TXD
UCA0CTL1 &= ~UCSWRST; // **Initialize USCI state machine**
IE2 |= UCA0TXIE;
}
Shopping information
MSP430G2 $9.99
https://estore.ti.com/MSP-EXP430G2-MSP430-LaunchPadValue-Line-Development-kit-P2031.aspx
MPU6050 $5.75
http://www.ebay.com/itm/MPU-6050-3-Axis-AccelerometerSensor-Gyroscope-6DOF-Module-3-3V-5V-For-Arduino/161108492494?pt=LH_DefaultDomain_0&hash=item2582d0
80ce

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