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//******************************************************************************
// MSP430F21x2 Demo - USCI_A0 IrDA Physical Layer Comm, 8MHz SMCLK
//
// Description: This example receives bytes through the USCI module
// configured for IrDA mode, and sends them out using the Timer_A UART
// to a PC running a terminal software. Likewise, data received from the PC
// through the Timer_A UART link is transmitted via IrDA.
//
// ACLK = n/a, MCLK = SMCLK = BRCLK = CALxxx_8MHZ = 8MHz
//
// MSP430F21x2
// -----------------------
// | |
// /|\| XIN|-
// | | |
// --|RST XOUT|-
// | |
// GP2W0116YPS /|\ | |
// ------- | | |
// | Vcc|-----+ IrDA | P2.4/TA2|--> 115,200 8N1
// # LED|-----+ 9600 8N1 | P2.3/TA1|<-- Terminal SW
// # TxD|<---------------|P3.4/UCA0TXD |
// # RxD|--------------->|P3.5/UCA0RXD |
// # SD|-----+ | |
// | GND|-----+ | |
// ------- | -----------------------
// ---
//
// A. Dannenberg
// Texas Instruments Inc.
// April 2006
// Built with CCE Version: 3.2.0 and IAR Embedded Workbench Version: 3.41A
//******************************************************************************
#include "msp430x21x2.h"
#define BITTIME 69 // UART bit time = 8MHz / 115,200
#define BITTIME_5 35 // UART half bit time
#define FLAG_USCI 0x01 // USCI data received
#define FLAG_UART 0x02 // Timer_A UART data received
unsigned int TXData; // Timer_A UART TX data
unsigned char TxBitCnt; // Timer_A UART TX bit counter
unsigned char RXData; // Timer_A UART RX data
unsigned char RxBitCnt; // Timer_A UART RX bit counter
unsigned char Flags; // Flag register
unsigned char RXDataIR; // Received IrDA data
// Function prototypes
void RX_Ready(void);
void TX_Byte(unsigned char Data);
void main(void)
{
WDTCTL = WDTPW + WDTHOLD; // Stop WDT
if (CALBC1_8MHZ ==0xFF || CALDCO_8MHZ == 0xFF)
{
while(1); // If calibration constants erased
// do not load, trap CPU!!
}
DCOCTL = CALDCO_8MHZ; // Load 8MHz constants
BCSCTL1 = CALBC1_8MHZ;
P2SEL |= 0x18; // Use P2.3/P2.4 for Timer_A
P2DIR |= 0x10; // P2.4 output
P3SEL |= 0x30; // Use P3.4/P3.5 for USCI_A0
UCA0CTL1 |= UCSWRST; // Set SW Reset
UCA0CTL1 = UCSSEL_2 + UCSWRST;
UCA0BR0 = 52; // 8MHz/52=153.8KHz
UCA0BR1 = 0;
UCA0MCTL = UCBRF_1 + UCOS16;
UCA0IRTCTL = UCIRTXPL2 + UCIRTXPL0 + UCIRTXCLK + UCIREN;
// Pulse length = 6 half clock cyc
// Enable BITCLK16, IrDA enc/dec
UCA0IRRCTL = UCIRRXPL; // Light = low pulse
UCA0CTL1 &= ~UCSWRST; // Resume operation
IE2 |= UCA0RXIE; // Enable RX int
TA0CCTL2 = OUT; // TXD Idle as Mark
TA0CTL = TASSEL_2 + MC_2; // SMCLK, continuous mode
RX_Ready(); // Ready Timer_A UART for RX
while (1)
{
__disable_interrupt(); // Disable interrupts
if (!Flags) // Any events pending?
__bis_SR_register(CPUOFF + GIE); // Enter LPM0 w/ interrupts
__enable_interrupt(); // Enable interrupts
if (Flags & FLAG_USCI) // USCI_A0 character received?
{
while (TACCTL2 & CCIE); // Yes, ensure Timer_A UART is ready
TX_Byte(RXDataIR); // Transmit using Timer_A UART
Flags &= ~FLAG_USCI; // Clear flag
IE2 |= UCA0RXIE; // Re-enable RX int
}
if (Flags & FLAG_UART) // Timer_A UART character received?
{
while (!(IFG2 & UCA0TXIFG)); // Ensure TX buffer is ready
UCA0TXBUF = RXData; // Move RX'd character to USCI_A0
Flags &= ~FLAG_UART; // Clear flag
RX_Ready(); // Ready Timer_A UART for RX
}
}
}
//------------------------------------------------------------------------------
// Read RXed character from USCI_A0, return from LPM0
//------------------------------------------------------------------------------
#pragma vector = USCIAB0RX_VECTOR
__interrupt void USCIAB0RX_ISR(void)
{
RXDataIR = UCA0RXBUF; // Get RXed character
IE2 &= ~UCA0RXIE; // Disable RX int
Flags |= FLAG_USCI; // Indicate received character
__bic_SR_register_on_exit(CPUOFF); // Return active after receiption
}
//------------------------------------------------------------------------------
// Readies the Timer_A UART to receive on byte
//------------------------------------------------------------------------------
void RX_Ready(void)
{
RxBitCnt = 8; // Load Bit counter
TA0CCTL1 = SCS + CCIS0 + CM1 + CAP + CCIE; // Sync, Neg Edge, Capture
}
//------------------------------------------------------------------------------
// TX the byte 'Data' using Timer_A UART
//------------------------------------------------------------------------------
void TX_Byte(unsigned char Data)
{
TxBitCnt = 10; // Load Bit counter, 8 data + ST/SP
TA0CCR2 = TAR; // Current state of TA counter
TA0CCR2 += BITTIME; // Some time till first bit
TXData = Data; // Load global variable
TXData |= 0x0100; // Add mark stop bit
TXData <<= 1; // Add space start bit
TACCTL2 = OUTMOD0 + CCIE; // TXD = mark = idle
}
//------------------------------------------------------------------------------
// Timer_A UART RX and TX
//------------------------------------------------------------------------------
#pragma vector=TIMER0_A1_VECTOR
__interrupt void Timer_A1_ISR(void)
{
switch (__even_in_range(TAIV, 10)) // Use calculated branching
{
case 2 : // TACCR1 CCIFG - UART RX
TA0CCR1 += BITTIME; // Add Offset to TACCR1
if (TACCTL1 & CAP) // Capture mode = start bit edge
{
TA0CCTL1 &= ~CAP; // Capture to compare mode
TACCR1 += BITTIME_5;
}
else
{
RXData >>= 1;
if (TA0CCTL1 & SCCI) // Get bit waiting in receive latch
RXData |= 0x80;
RxBitCnt--;
if (RxBitCnt == 0) // All bits RXed?
{
TA0CCTL1 &= ~CCIE; // All bits RXed, disable interrupt
Flags |= FLAG_UART; // Indicate received character
__bic_SR_register_on_exit(CPUOFF);// Clear LPM0 bits from 0(SR)
}
}
break;
case 4 : // TACCR2 CCIFG - UART TX
TA0CCR2 += BITTIME; // Add Offset to TACCR2
if (TxBitCnt == 0) // All bits TXed?
{
TA0CCTL2 &= ~CCIE; // All bits TXed, disable interrupt
__bic_SR_register_on_exit(CPUOFF); // Clear LPM0 bits from 0(SR)
}
else
{
if (TXData & 0x01)
TA0CCTL2 &= ~OUTMOD2; // TX Mark
else
TA0CCTL2 |= OUTMOD2; // TX Space
TXData >>= 1;
TxBitCnt--;
}
break;
}
}
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