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Файл:Микропроцессорная техника / MSP430G2xx3_Code_Examples / msp430g2xx3_uscib0_i2c_02
.c/* --COPYRIGHT--,BSD_EX
* Copyright (c) 2012, Texas Instruments Incorporated
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* * Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* * Neither the name of Texas Instruments Incorporated nor the names of
* its contributors may be used to endorse or promote products derived
* from this software without specific prior written permission.
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
* THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
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* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
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*******************************************************************************
*
* MSP430 CODE EXAMPLE DISCLAIMER
*
* MSP430 code examples are self-contained low-level programs that typically
* demonstrate a single peripheral function or device feature in a highly
* concise manner. For this the code may rely on the device's power-on default
* register values and settings such as the clock configuration and care must
* be taken when combining code from several examples to avoid potential side
* effects. Also see www.ti.com/grace for a GUI- and www.ti.com/msp430ware
* for an API functional library-approach to peripheral configuration.
*
* --/COPYRIGHT--*/
//******************************************************************************
// MSP430G2xx3 Demo - USCI_B0 I2C Master Interface to PCF8574, Read/Write
//
// Description: I2C communication with a PCF8574 in read and write mode is
// demonstrated. PCF8574 port P is configured with P0-P3 input, P4-P7. Read
// P0-P3 input data is written back to Port P4-P7. This example uses the
// RX ISR and generates an I2C restart condition while switching from
// master receiver to master transmitter.
// ACLK = n/a, MCLK = SMCLK = TACLK = BRCLK = default DCO = ~1.2MHz
//
// MSP430G2xx3
// -----------------
// /|\ /|\ /|\| XIN|-
// 10k 10k | | |
// PCF8574 | | --|RST XOUT|-
// --------- | | | |
// --->|P0 SDA|<-|---+---->|P1.7/UCB0SDA |
// --->|P1 | | | |
// --->|P2 | | | |
// --->|P3 SCL|<-+---------|P1.6/UCB0SCL |
// <---|P4 | | |
// <---|P5 | | |
// <---|P6 | | |
// <---|P7 | | |
// +--|A0,A1,A2 | | |
// | | | | |
// \|/
//
// D. Dang
// Texas Instruments Inc.
// February 2011
// Built with CCS Version 4.2.0 and IAR Embedded Workbench Version: 5.10
//******************************************************************************
#include <msp430.h>
int main(void)
{
WDTCTL = WDTPW + WDTHOLD; // Stop Watchdog Timer
P1SEL |= BIT6 + BIT7; // Assign I2C pins to USCI_B0
P1SEL2|= BIT6 + BIT7; // Assign I2C pins to USCI_B0
UCB0CTL1 |= UCSWRST; // Enable SW reset
UCB0CTL0 = UCMST+UCMODE_3+UCSYNC; // I2C Master, synchronous mode
UCB0CTL1 = UCSSEL_2+UCSWRST; // Use SMCLK, keep SW reset
UCB0BR0 = 12; // fSCL = SMCLK/12 = ~100kHz
UCB0BR1 = 0;
UCB0I2CSA = 0x20; // Set slave address
UCB0CTL1 &= ~UCSWRST; // Clear SW reset, resume operation
IE2 |= UCB0RXIE; // Enable RX interrupt
TACCTL0 = CCIE; // TACCR0 interrupt enabled
TACTL = TASSEL_2 + MC_2; // SMCLK, contmode
while (1)
{
__bis_SR_register(CPUOFF + GIE); // CPU off, interrupts enabled
UCB0CTL1 &= ~UCTR; // I2C RX
UCB0CTL1 |= UCTXSTT; // I2C start condition
while (UCB0CTL1 & UCTXSTT); // Loop until I2C STT is sent
UCB0CTL1 |= UCTR + UCTXSTT; // I2C TX, start condition
__bis_SR_register(CPUOFF + GIE); // CPU off, interrupts enabled
while (UCB0CTL1 & UCTXSTT); // Loop until I2C STT is sent
UCB0CTL1 |= UCTXSTP; // I2C stop condition after 1st TX
}
}
#pragma vector = TIMER0_A0_VECTOR
__interrupt void TA0_ISR(void)
{
__bic_SR_register_on_exit(CPUOFF); // Exit LPM0
}
// USCI_B0 Data ISR
#pragma vector = USCIAB0TX_VECTOR
__interrupt void USCIAB0TX_ISR(void)
{
UCB0TXBUF = (UCB0RXBUF << 4) | 0x0f; // Move RX data to TX
__bic_SR_register_on_exit(CPUOFF); // Exit LPM0
}
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