Lab 1I/O, timers, interruptson the eZ430-RF2500

Thomas WatteyneEE290Q – Spring 2010

http://wsn.eecs.berkeley.edu/290Q

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MSP430• “Heart” of the eZ430-

RF2500– 16-bit 16MHz RISC– 32kB ROM, 1kB RAM– 2 Timers, USCI, 10-bit

ADCs• Debug capabilities using

JTAG• Low Power Operation

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CC2500• Any frequency on the 2.4-

2.485GHz band– Not 802.15.4-compliant

• Wake-on-radio support– Preamble sampling in

hardware

• 47 configuration registers– Switch Tx/Rx/idle– TXBUF, RXBUF– Tx power and frequency

• Follows a state machineSmartRF Studio

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Interconnection

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Chip Select

Clock

SPI interfaceinterrupts

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eZ430-RF2500

2 LEDspushbutton

CC2500

chip antenna

26MHz crystal

for radio

extension ports

MSP430

USB programmer:• Power• Debug (JTAG) • Interface (serial)

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Extension Pins• P1: GND• P2: VCC_EXT• P3: P2.0 I/O, ACLK, OA010• P4: P2.1 I/O, Timer_A3.INCLK, SMCLK, OA0O• P5: P2.2 I/O, Timer_A3.CCI0B, Timer_A3.TA0, OA• P6: P2.3 I/O, Timer_A3.CCI1B, Timer_A3.TA1, OA• P7: P2.4 I/O, Timer_A3.TA2, OA• P8: P4.3 I/O, Timer_B3.CCI0B, Timer_B3.TB0, OA• P9: P4.4 I/O, Timer_B3.CCI1B, Timer_B3.TB1, OA• P10: P4.5 I/O, Timer_B3.TB2, OA• P11: P4.6 I/O, OA• P12: GND• P13: GDO0 I/O from the CC2500 (configurable)• P14: GDO2 I/O from the CC2500 (configurable)• P15: P3.2 I/O, UC1SOMI• P16: P3.3 I/O, UC1CLK• P17: P3.0 I/O• P18: P3.1 I/O, UC1SIMO

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IAR Kickstartproject file navigator

compile

open files

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Talking with your mote over “USB”

• Use Windows Device Manager to idenfify the COM port the eZ430-RF2500 is on

• Use PuTTY to connect to that port

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Operations on binary data

• A = 0b01101001• ~A = 0b10010110• A |= 0b00000010 => A=0b01101011• A &=~0b00001000 => A=0b01100001• A ^= 0b10001000 => A=0b11100001• A<<2 => A=0b10100100• A>>2 => A=0b00011010

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I/O port registers

• P1DIR: direction, 0=in, 1=out• P1OUT: set output• P1IN: read input

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A steady LED

led_steady

Disable watchdog

timer

P1.0 and P1.1 as output

P1.0=1 and P1.1=1

Continue executing

#include "io430.h"#include "in430.h"int main( void ){ WDTCTL = WDTPW + WDTHOLD; P1DIR |= 0x03; P1OUT |= 0x03; while(1);}

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Active Waiting Loop

led_loop

#include "io430.h"#include "in430.h"int main( void ){ WDTCTL = WDTPW + WDTHOLD; int i; P1DIR |= 0x03; while (1) { P1OUT ^= 0x03; for (i=0;i<10000;i++) { __no_operation(); } }}

P1.0 and P1.1 as output

Change Led state (aka toggle)

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Interrupt

• Interrupt only when both– General interrupt enabled in status register– Specific interrupt enabled in specific register

• Interrupt Service Routine written as:#pragma vector=TIMERA0_VECTOR

• ISR sometimes needs to clear an interrupt flag in a specific register

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Button-Driven Toggle Through Interrupts

led_button

#include "io430.h"#include "in430.h"int main( void ){ WDTCTL = WDTPW + WDTHOLD; P1DIR |= 0x03; P1DIR &= ~0x04; P1REN |= 0x04; P1IE |= 0x04; __bis_SR_register(GIE); while(1);}

#pragma vector=PORT1_VECTOR__interrupt void Port_1 (void){ P1IFG &= ~0x04; P1OUT ^= 0x03;}

P1.2 as input

enable resistor (for button)

enable interrupt for P1.2 globally enable

interrupts (do this last)

Executed when interrupt from P1

Actual function name has no importance

Clear interrupt flag (mandatory)

Toggle LEDs

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Timer

• A timer is a counter which– Counts in a certain way (up, down, continuous)– At every clock tick

• Can be used in two ways:– Triggers interrupts when reaching a given value

(compare mode)or– Records its timer value on other interrupts

(capture mode)

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Timer-Driven Toggle Through Timer Interrupts

led_timer

#include "io430.h"#include "in430.h"int main( void ){ WDTCTL = WDTPW + WDTHOLD; P1DIR |= 0x03; TACCTL0 = CCIE; TACCR0 = 1000; TACTL = TASSEL_1 + MC_1;__bis_SR_register(GIE+LPM3_bits);}

#pragma vector=TIMERA0_VECTOR__interrupt void Timer_A (void){ P1OUT ^= 0x03;}

Timer_A interrupt enable Capture Compare

to 1000

Count following ACLK

Count in up mode

interrupt interrupt

Globally enable interrupt

low power mode, waiting for interrupts

Executed at each Timer_A interrupt