Master data should increment from 0x00 with each transmitted byte ; which is verified by the slave.. ; LED off for address or data Ack; LED on for address or data NAck.d by the slave.
Trang 1; MSP430G2x21/G2x31 Demo - I2C Slave Receiver, single byte
;
; Description: I2C Slave communicates with I2C Master using
; the USI Master data should increment from 0x00 with each transmitted byte
; which is verified by the slave
; LED off for address or data Ack; LED on for address or data NAck.d by the slave
; ACLK = n/a, MCLK = SMCLK = Calibrated 1MHz
;
; ***THIS IS THE SLAVE CODE***
;
; Slave Master
; (msp430g2x21_usi_07.asm)
; MSP430G2x21/G2x31 MSP430G2x21/G2x31
;
-; /|\| /|\|
XIN|-; | | | | | |
; |RST |RST
XOUT|-; | | | |
; LED <-|P1.0 | | |
; | | | P1.0|-> LED
; | SDA/P1.7|< -|P1.7/SDA |
; | SCL/P1.6|< -|P1.6/SCL |
;
; Note: internal pull-ups are used in this example for SDA & SCL
;
; D Dang
; Texas Instruments Inc
; October 2010
; Built with Code Composer Essentials Version: 4.2.0
;****************************************************************************** I2CState .equ R4
MST_data .equ R5
slav_add .equ R6
cdecls C,LIST, "msp430g2221.h"
.text ; Program Start
; -RESET mov.w #0280h,SP ; Initialize stackpointer
StopWDT mov.w #WDTPW+WDTHOLD,&WDTCTL ; Stop watchdog timer
CheckCal cmp.b #0FFh,&CALBC1_1MHZ ; Calibration constants erased? jeq Trap
cmp.b #0FFh,&CALDCO_1MHZ
jne Load
Trap jmp $ ; Trap CPU!!
Load mov.b &CALBC1_1MHZ,&BCSCTL1 ; Set DCO to 1MHz
mov.b &CALDCO_1MHZ,&DCOCTL
SetupP1 mov.b #0xC0,&P1OUT ; P1.6 &P1.7 pullups
bis.b #0xC0,&P1REN ; P1.6 &P1.7 pullups
mov.b #0xFF,&P1DIR ; unused pins output direction SetupP2 clr.b &P2OUT ;
mov.b #0xFF,&P2DIR
SetupUSI mov.b #USIPE6+USIPE7+USISWRST,&USICTL0; Port, I2C slave
mov.b #USIIE+USII2C+USISTTIE,&USICTL1 ;Enable I2C mode,interrupts mov.b #USICKPL,&USICKCTL ; Setup clock polarity
bis.b #USIIFGCC,&USICNT
bic.b #USISWRST,&USICTL0
bic.b #USIIFG,&USICTL1
clr.w I2CState
Trang 2clr.w MST_data
mov.b #0x90,slav_add Mainloop
bis.w #LPM0+GIE,SR ; Enter LPM0, enable interrupts jmp Mainloop
; -USI_ISR ;
bit.b #USISTTIFG,&USICTL1 ; Start entry?
jnc Check_State
bis.b #0x01,&P1OUT ; turn on LED, sequence start
mov.w #2,I2CState ; First I2C state, Rx address
Check_State add.w I2CState,PC ; I2C State Machine
jmp STATE0
jmp STATE2
jmp STATE4
jmp STATE6
jmp STATE8
jmp STATE10
STATE0 nop ; Idle, should not get here
bic.b #USIIFG,&USICTL1
reti
STATE2 ; Rx address
mov.b &USICNT,R8 ; Bit counter = 8, Rx address
and.b #0xE0,R8
add.b #0x8,R8
mov.b R8,&USICNT
bic.b #USISTTIFG,&USICTL1 ; Clear Start flag
mov.w #4,I2CState ; Go to next state, chk address bic.b #USIIFG,&USICTL1
reti
STATE4 ; Process address and send (N)Ack bit.b #0X01,&USISRL ; If read
jnc Chk_Add
inc.b slav_add ; Save R/W bit
Chk_Add
bis.b #USIOE,&USICTL0 ; SDA = output
cmp.b slav_add,&USISRL ; address match?
jnz Add_NACK
clr.b &USISRL
bic.b #0x01,&P1OUT ; LED off
mov.w #8,I2CState ; Go to next state: Rx data
bis.b #0x01,&USICNT ; Bit counter = 1, send Ack bit bic.b #USIIFG,&USICTL1
reti
Add_NACK
mov.b #0xFF,&USISRL ; Send NACK
bis.b #0x1,&P1OUT ; LED on:error
mov.w #6,I2CState ; go to next state, prep next start bis.b #0x01,&USICNT ; Bit counter = 1, Send Nack
bic.b #USIIFG,&USICTL1
reti
STATE6 ; Prep for Re-start condition
bic.b #USIOE,&USICTL0 ; SDA = input
mov.b #0x90,slav_add ; Reset Slave address
clr.w I2CState ; Reset state machine
bic.b #USIIFG,&USICTL1
reti
STATE8 ; Receive data byte
Trang 3bic.b #USIOE,&USICTL0 ; SDA =input
bis.b #0x8,&USICNT ; Bit counter = 8, Rx data
mov.w #10,I2CState ; Go to next state,test data,(N)Ack bic.b #USIIFG,&USICTL1
reti
STATE10 ; Check Data and Tx (N)Ack
bis.b #USIOE,&USICTL0 ; SDA = output
cmp.b MST_data,&USISRL ; If data valid
jne Data_NACK
clr.b &USISRL ; Send Ack
inc.b MST_data ; Increment master data
bic.b #0x1,&P1OUT ; LED off
jmp STATE10_Exit
Data_NACK
mov.b #0xFF,&USISRL ; Send Nack
bis.b #0x1,&P1OUT ; LED on : error
STATE10_Exit
bis.b #0x1,&USICNT ; Bit counter = 1, Send Nack
mov.w #6,I2CState ; next state, prep for next start bic.b #USIIFG,&USICTL1
reti
; -; Interrupt Vectors
.sect ".reset" ; MSP430 RESET Vector
short RESET ;
sect ".int04" ; USI Vector
short USI_ISR ;
end