Monat: August 2012

Das Beispielprogramm ruft mit 50 Hz den ADC auf welcher eine Serie an Messungen macht (Channel A1, dann A0). Der ADC triggert nach jeder Messung die DMA welche das Messergebnis abholt und in das Array ADC_Result schreibt. Das alles läuft völlig ohne CPU Interaktion.

[c]
#include „msp430fr5739.h“

unsigned int ADC_Result[2];

void main(void)
{
WDTCTL = WDTPW + WDTHOLD; // Stop WDT

// Setup clock system
CSCTL0_H = 0xA5; // Password
CSCTL1 |= DCOFSEL0 + DCOFSEL1; // DCO 8 MHz
CSCTL2 = SELA_3 + SELS_3 + SELM_3; // set ACLK = SMCLK = DCO/8

// Port Setup
P1SEL0 |= BIT0; // P1.0 is input for ADC
P1SEL1 |= BIT0; // Channel A0
P1SEL1 |= BIT1; // P1.1 is input for ADC
P1SEL0 |= BIT1; // Channel A1

// Setup der DMA
DMACTL0 |= DMA0TSEL__ADC10IFG; // ADC10 interrupt soll die DMA triggern
__data16_write_addr((unsigned short)&DMA0SA,(unsigned long) &ADC10MEM0);
// DMA soll das ADC Ergebnis lesen…
__data16_write_addr((unsigned short)&DMA0DA,(unsigned long) &ADC_Result[0]);
// …und ins array ADC_Result[] schreiben
DMA0SZ = 2; // One word per transfer
DMA0CTL |= DMADT_4; // Repeated single transfer
DMA0CTL &= ~DMADSTBYTE; // DMA destination is a word
DMA0CTL &= ~DMASRCBYTE; // DMA source is a word
DMA0CTL |= DMASRCINCR_0; // Source address is unchanged (immer gleiches Register)
DMA0CTL |= DMADSTINCR_3; // Destination address is incremented (nächstes array element)
DMA0CTL &= ~DMALEVEL; // Trigger on low level (otherwise DMA is too fast)
DMA0CTL |= DMAIE; // Enable Interrupts
DMA0CTL |= DMAEN; // Enable DMA

// Setup Timer
TA0CCR0 = 20000 – 1; // PWM Period 50 Hz
TA0CCTL1 = OUTMOD_7; // CCR1 reset/set
TA0CCR1 = 2000; // CCR1 PWM duty cycle 10 %
TA0CTL = TASSEL_2 + MC_1 + TACLR; // SMCLK, up mode, clear TAR

// Setup ADC
ADC10CTL0 &= ~ADC10ENC;
ADC10CTL1 |= ADC10CONSEQ_3; // Repeat-Sequence-of-Channels Mode
ADC10CTL1 |= ADC10SHS_1; // Set PWM as trigger source
ADC10CTL1 &= ~ADC10SHP; // Bypass Sample timer
ADC10CTL2 |= ADC10RES; // 10-bit conversion results
ADC10MCTL0 |= ADC10INCH_1; // Start Sequence with Channel A1
ADC10CTL0 |= ADC10ON; // ADC on
ADC10CTL0 |= ADC10ENC; // Enable ADC conversation

_BIS_SR(GIE); // General interrupt enable

while(1) __bic_SR_register(CPUOFF); // CPU off
}

#pragma vector=DMA_VECTOR
__interrupt void DMA0_ISR (void)
{
switch(__even_in_range(DMAIV,16))
{
case 0: break; // No interrupt
case 2:
// ADC and DMA are ready, values are now stored in Array ADC_Result
__no_operation(); // Set breakpoint here
break; // DMA0IFG
case 4: break; // DMA1IFG
case 6: break; // DMA2IFG
case 8: break; // Reserved
case 10: break; // Reserved
case 12: break; // Reserved
case 14: break; // Reserved
case 16: break; // Reserved
default: break;
}
}
[/c]

Das geht in C so:

[c]
PMMCTL0_H = PMMPW_H; // Enter PMM password
PMMCTL0_L |= PMMREGOFF; // Enter LPMx.5 when PMMREGOFF is set

__bis_SR_register([LPM3;LPM4]_bits); // Enter LPM
[/c]

Der ADC10B des MSP430 kann auch automatisch mehrere Kanäle nacheinander messen, ohne dass manuell hin und her geschaltet werden muss.
Das folgende Programm misst zunächst Kanal A1 und dann A0. Der ADC fängt immer beim höchsten in ADC10MCTL0 eingestellen Kanal an und zählt dann herunter. Nach jeder Messung wird in diesem Programm ein Interrupt ausgelöst und der gerade gemessene Wert kann ausgelesen werden.

[c]
#include „msp430fr5739.h“

unsigned int ADC_Result;

void main(void)
{
WDTCTL = WDTPW + WDTHOLD; // Stop WDT

// Setup clock system
CSCTL0_H = 0xA5; // Password
CSCTL1 |= DCOFSEL0 + DCOFSEL1; // DCO 8 MHz
CSCTL2 = SELA_3 + SELS_3 + SELM_3; // set ACLK = SMCLK = DCO/8

// Port Setup
P1SEL0 |= BIT0; // P1.0 is input for ADC
P1SEL1 |= BIT0; // Channel A0
P1SEL1 |= BIT1; // P1.1 is input for ADC
P1SEL0 |= BIT1; // Channel A1

// Setup Timer
TA0CCR0 = 20000 – 1; // PWM Period 50 Hz
TA0CCTL1 = OUTMOD_7; // CCR1 reset/set
TA0CCR1 = 2000; // CCR1 PWM duty cycle 10 %
TA0CTL = TASSEL_2 + MC_1 + TACLR; // SMCLK, up mode, clear TAR

// Setup ADC
ADC10CTL0 &= ~ADC10ENC;
ADC10CTL0 |= ADC10SHT_2 + ADC10ON; // ADC10ON, S&H=16 ADC clks
ADC10CTL1 |= ADC10CONSEQ_3; // Repeat-Sequence-of-Channels Mode
ADC10CTL1 |= ADC10SHS_1; // Set PWM as trigger source
ADC10CTL1 &= ~ADC10SHP; // Bypass Sample timer
ADC10CTL2 |= ADC10RES; // 10-bit conversion results
ADC10MCTL0 |= ADC10INCH_1; // Start Sequence with Channel A1
ADC10IE |= ADC10IE0; // Enable ADC conv complete interrupt
ADC10CTL0 |= ADC10ENC; // Enable ADC conversation

_BIS_SR(GIE);

while(1) __bic_SR_register(CPUOFF);
}

#pragma vector=ADC10_VECTOR
__interrupt void ADC10_ISR(void)
{
__no_operation();
switch(__even_in_range(ADC10IV,12))
{
case 0: break; // No interrupt
case 2: break; // conversion result overflow
case 4: break; // conversion time overflow
case 6: break; // ADC10HI
case 8: break; // ADC10LO
case 10: break; // ADC10IN
case 12:
ADC_Result = ADC10MEM0;
__no_operation();
__bic_SR_register_on_exit(CPUOFF);
break;

default: break;
}
}
[/c]

Im folgenden Beispiel wird mit dem Timer A0 eine PWM (50 Hz, 10 % duty cycle) erzeugt welche ohne CPU Interaktion den ADC 10B des MSP430FR5739 triggert und eine Messung auslöst. Gemessen wird die Spannung an Port 1.1. Ist der ADC fertig wird ein Interrupt ausgelöst.
Nur während die ISR läuft wacht die CPU kurz auf.

[c]
#include „msp430fr5739.h“

unsigned int ADC_Result;

void main(void)
{
WDTCTL = WDTPW + WDTHOLD; // Stop WDT

// Setup clock system
CSCTL0_H = 0xA5; // Password
CSCTL1 |= DCOFSEL0 + DCOFSEL1; // DCO 8 MHz
CSCTL2 = SELA_3 + SELS_3 + SELM_3; // set ACLK = SMCLK = DCO/8

// Port Setup
P1DIR |= BIT0; // Set P1.0 to output direction
P1SEL0 |= BIT0; // P1.0 is output for PWM for debugging
P1SEL1 |= BIT1; // P1.1 is input for ADC
P1SEL0 |= BIT1; // P1.1 is input for ADC

// Setup Timer
TA0CCR0 = 20000 – 1; // PWM Period 50 Hz
TA0CCTL1 = OUTMOD_7; // CCR1 reset/set
TA0CCR1 = 2000; // CCR1 PWM duty cycle 10 %
TA0CTL = TASSEL_2 + MC_1 + TACLR; // SMCLK, up mode, clear TAR

// Setup ADC
ADC10CTL0 &= ~ADC10ENC;
ADC10CTL0 |= ADC10SHT_2 + ADC10ON; // ADC10ON, S&H=16 ADC clks
ADC10CTL1 |= ADC10CONSEQ_2; // Single-channel repeat
ADC10CTL1 |= ADC10SHS_1; // Set PWM as trigger source
ADC10CTL1 &= ~ADC10SHP; // Bypass Sample timer
ADC10CTL2 |= ADC10RES; // 10-bit conversion results
ADC10MCTL0 |= ADC10INCH_1; // A1 ADC input select; Vref=AVCC
ADC10IE |= ADC10IE0; // Enable ADC conv complete interrupt
ADC10CTL0 |= ADC10ENC; // Enable ADC conversation

_BIS_SR(GIE);

while(1) __bic_SR_register(CPUOFF);
}

#pragma vector=ADC10_VECTOR
__interrupt void ADC10_ISR(void)
{
__no_operation();
switch(__even_in_range(ADC10IV,12))
{
case 0: break; // No interrupt
case 2: break; // conversion result overflow
case 4: break; // conversion time overflow
case 6: break; // ADC10HI
case 8: break; // ADC10LO
case 10: break; // ADC10IN
case 12:
ADC_Result = ADC10MEM0;
__no_operation();
__bic_SR_register_on_exit(CPUOFF);
break;

default: break;
}
}
[/c]

Das folgende Programm verschickt auf Tasterdruck (S2) ein byte (0x22) per SPI.

[c]
// P1.5 = SCLK
// P1.6 = DOUT
// P1.7 = DIN

#include

void main(void)
{

WDTCTL = WDTPW + WDTHOLD; // Stop watchdog timer

// Port 1.3: Switch Input
P1DIR &= ~BIT3; // P1.3 = input
P1REN |= BIT3; // Pullup/down resistor enabled
P1OUT |= BIT3; // Pin is pulled enabled
P1IE |= BIT3; // Enable interrupts from switch
P1IES |= BIT3; // rising edge

// Setup USI -> SPI Master
USICTL0 |= USIPE7 + USIPE6 + USIPE5 + USIMST + USIOE; // Port, SPI master
USICTL1 |= USIIE; // Counter interrupt, flag remains set
USICTL1 |= USICKPH; // Data is captured on the first SCLK edge and changed on the following edge
USICKCTL = USIDIV_4 + USISSEL_2; // /16 SMCLK
USICTL1 &= ~USIIFG; // reset IRQ flag
USICTL0 &= ~USISWRST; // USI released for operation

_BIS_SR(GIE);
while(1);
}

#pragma vector=USI_VECTOR
__interrupt void universal_serial_interface(void)
{
USICTL1 &= ~USIIFG; // reset IRQ flag
}

#pragma vector=PORT1_VECTOR
__interrupt void Port_1(void)
{
P1IE &= ~BIT3; // Disable interrupts from switch

USISRL = 0x22; // write data to send into fifo
USICNT = 8; // reload counter

P1IFG &= ~BIT3; // clear Interrupt Flag
P1IE |= BIT3; // Enable interrupts from switch
}
[/c]

Mit dem folgenden Programm können die Daten auf einem zweiten LaunchPad empfangen werden:

[c]
#include

void main(void)
{
int received_data[1];
WDTCTL = WDTPW + WDTHOLD; // Stop watchdog timer

// Setup USI -> SPI Slave
USICTL0 |= USIPE7 + USIPE6 + USIPE5 + USIOE; // Port setup
USICNT &= ~USI16B; // only 8 bit mode
USICTL0 &= ~USIMST; // SPI slave
USICTL1 |= USIIE; // Counter interrupt, flag remains set
USICTL1 |= USICKPH; // Data is captured on the first SCLK edge and changed on the following edge
USICKCTL = USIDIV_4 + USISSEL_2; // /16 SMCLK
USICTL1 &= ~USIIFG; // reset IRQ flag
USICTL0 &= ~USISWRST; // USI released for operation
received_data[0] = USISRH;
received_data[0] = USISRL; // Empty USISRL
//USISRL = 0x22;
USICNT = 7; // init-load counter

_BIS_SR(GIE);
while(1);

}

#pragma vector=USI_VECTOR
__interrupt void universal_serial_interface(void)
{
int received_data[1];
received_data[0] = USISRH;
received_data[0] = USISRL;

USICNT = 7;
USICTL1 &= ~USIIFG; // reset IRQ flag
}
[/c]