📄 11x1_uart2.s43
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#include "msp430x11x1.h"
;******************************************************************************
; MSP430x11x(1) Demo - 9600-baud UART using 32kHz Crystal
;
; Description: This program demonstrates a half-duplex 9600-baud UART using
; Timer_A3 and a 32kHz crystal. The program will wait in LPM3, echoing back
; a received character using 8N1 protocal. The Set_DCO subroutine will
; calibrate the DCOCLK to 1228800, which will is used as the Timer_A clock.
;
; THIS PROGRAM IS PROVIDED "AS IS". TI MAKES NO WARRANTIES OR
; REPRESENTATIONS, EITHER EXPRESS, IMPLIED OR STATUTORY,
; INCLUDING ANY IMPLIED WARRANTIES OF MERCHANTABILITY, FITNESS
; FOR A PARTICULAR PURPOSE, LACK OF VIRUSES, ACCURACY OR
; COMPLETENESS OF RESPONSES, RESULTS AND LACK OF NEGLIGENCE.
; TI DISCLAIMS ANY WARRANTY OF TITLE, QUIET ENJOYMENT, QUIET
; POSSESSION, AND NON-INFRINGEMENT OF ANY THIRD PARTY
; INTELLECTUAL PROPERTY RIGHTS WITH REGARD TO THE PROGRAM OR
; YOUR USE OF THE PROGRAM.
;
; IN NO EVENT SHALL TI BE LIABLE FOR ANY SPECIAL, INCIDENTAL,
; CONSEQUENTIAL OR INDIRECT DAMAGES, HOWEVER CAUSED, ON ANY
; THEORY OF LIABILITY AND WHETHER OR NOT TI HAS BEEN ADVISED
; OF THE POSSIBILITY OF SUCH DAMAGES, ARISING IN ANY WAY OUT
; OF THIS AGREEMENT, THE PROGRAM, OR YOUR USE OF THE PROGRAM.
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; OF GOODWILL, LOSS OF PROFITS, LOSS OF SAVINGS, OR LOSS OF
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; AGGREGATE LIABILITY UNDER THIS AGREEMENT OR ARISING OUT OF
; YOUR USE OF THE PROGRAM EXCEED FIVE HUNDRED DOLLARS
; (U.S.$500).
;
; Unless otherwise stated, the Program written and copyrighted
; by Texas Instruments is distributed as "freeware". You may,
; only under TI's copyright in the Program, use and modify the
; Program without any charge or restriction. You may
; distribute to third parties, provided that you transfer a
; copy of this license to the third party and the third party
; agrees to these terms by its first use of the Program. You
; must reproduce the copyright notice and any other legend of
; ownership on each copy or partial copy, of the Program.
;
; You acknowledge and agree that the Program contains
; copyrighted material, trade secrets and other TI proprietary
; information and is protected by copyright laws,
; international copyright treaties, and trade secret laws, as
; well as other intellectual property laws. To protect TI's
; rights in the Program, you agree not to decompile, reverse
; engineer, disassemble or otherwise translate any object code
; versions of the Program to a human-readable form. You agree
; that in no event will you alter, remove or destroy any
; copyright notice included in the Program. TI reserves all
; rights not specifically granted under this license. Except
; as specifically provided herein, nothing in this agreement
; shall be construed as conferring by implication, estoppel,
; or otherwise, upon you, any license or other right under any
; TI patents, copyrights or trade secrets.
;
; You may not use the Program in non-TI devices.
;
; MSP430F1121
; -----------------
; /|\| XIN|-
; | | | 32k
; --|RST XOUT|-
; | |
; | | 9600 8N1
; | TX/P1.1|-------->
; | TX/P2.2|<--------
;
; CPU registers used
#define RXTXData R4
#define BitCnt R5
;
; Conditions for 9600 Baud HW/SW UART, SMCLK = DCOCLK = 1228800
Bitime_5 equ 0064 ; 0.5 bit length
Bitime equ 0128 ; 104 us
Delta equ 300 ; DCOCLK = (Delta)/(32768/8)
RXD set 004h ; RXD on P2.2
TXD set 002h ; TXD on P1.1
;
; M.Buccini
; Texas Instruments, Inc
; March 2002
;******************************************************************************
;-----------------------------------------------------------------------------
ORG 0F000h ; Program Start
;-----------------------------------------------------------------------------
RESET mov.w #300h,SP ; Initialize Stackpointer
call #Init_Sys ; Initialize System Peripherals
;
Mainloop call #RX_Ready ; UART ready to RX one Byte
bis.w #LPM3,SR ; Enter LPM3 Until Byte RXed
call #TX_Byte ; TX Back RXed Byte Received
jmp Mainloop ;
;
;-----------------------------------------------------------------------------
Init_Sys; Initialize System Peripherals
;-----------------------------------------------------------------------------
StopWDT mov.w #WDTPW+WDTHOLD,&WDTCTL ; Stop WDT
SetupBC bis.b #DIVA1+DIVA0,&BCSCTL1 ; ACLK=LFXT1CLK/8
SetupC0 mov.w #OUT,&CCTL0 ; TXD Idle as Mark
SetupTA mov.w #TASSEL1+MC1,&TACTL ; SMCLK, continous mode
SetupP1_2 bis.b #TXD,&P1SEL ; P1.1/TA0 for TXD function
bis.b #TXD,&P1DIR ; TXD output on P1
bis.b #RXD,&P2SEL ; P2.2/TA0 as RXD input
call #Set_DCO ; Calibrate DCO
eint ; General enable interrupts
ret ; Return from subroutine
;
;-----------------------------------------------------------------------------
TX_Byte ; Subroutine that Transmit One Byte from RXTXData Buffer.
;-----------------------------------------------------------------------------
mov.w &TAR,&CCR0 ; Current state of TA Counter
add.w #Bitime,&CCR0 ; Some time till first bit
bis.w #0100h, RXTXData ; Add mark stop bit to RXTXData
rla.w RXTXData ; Add space start bit
mov.w #10,BitCnt ; Load Bit Counter, 8data + ST/SP
mov.w #OUTMOD0+CCIE,&CCTL0 ; TXD = mark = idle
TX_Wait bit.w #CCIE,&CCTL0 ; Wait for TX completion
jnz TX_Wait ;
ret ;
;
;-----------------------------------------------------------------------------
RX_Ready ; Subroutine that will Receive One Byte into RXTXData Buffer.
; !!Sync capture not possible as TACLK can be off in this example!!
;-----------------------------------------------------------------------------
mov.w #08,BitCnt ; Load Bit Counter, 8 data bits
SetupRX mov.w #CCIS0+OUTMOD0+CM1+CAP+CCIE,&CCTL0 ; Neg Edge,Cap
ret ;
;
;-----------------------------------------------------------------------------
TA0_ISR ; CCR0/UART ISR: RXTXData Buffer holds UART Data.
;-----------------------------------------------------------------------------
add.w #Bitime,&CCR0 ; Time to Next Bit
bit.w #CCIS0,&CCTL0 ; RX on ISCCIB?
jnz UART_RX ; Jump --> RX
UART_TX cmp.w #00h,BitCnt ;
jne TX_Next ; Next bit?
bic.w #CCIE,&CCTL0 ; All Bits TX or RX, Disable Int.
reti ;
TX_Next bic.w #OUTMOD2,&CCTL0 ; TX Mark
rra.w RXTXData ; LSB is shifted to carry
jc TX_Test ; Jump --> bit = 1
TX_Space bis.w #OUTMOD2,&CCTL0 ; TX Space
TX_Test dec.w BitCnt ; All bits sent (or received)?
reti ;
;
UART_RX bit.w #CAP,&CCTL0 ; Compare mode for start bit edge
jz RX_Bit ; Start bit edge?
RX_Edge bic.w #CAP,&CCTL0 ; Switch to Compare mode
add.w #Bitime_5,&CCR0 ; First databit 1.5 bits from edge
mov.w #CPUOFF+GIE,0(SP) ; !!! DCO needs to remain on !!!
reti ;
RX_Bit bit.w #SCCI,&CCTL0 ; Get bit waiting in receive latch
rrc.b RXTXData ; Store received bit
RX_Test dec.w BitCnt ; All bits sent (or received)?
jnz RX_Next ; Next bit?
;>>>>>>>>>> Decode of Received Byte Here <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<
RX_Comp bic.w #CCIE,&CCTL0 ; All Bits RXed, Disable Interrupt
mov.w #GIE,0(SP) ; Decode Byte= Active in Mainloop
;>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>><<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<
RX_Next reti ;
;
;-----------------------------------------------------------------------------
Set_DCO; Subroutine: Sets DCO to selected frequency based on Delta.
; R14 and R15 are used, ACLK= 32768/8 Timer_A clocked by DCOCLK
;-----------------------------------------------------------------------------
clr.w R15 ;
Setup_CC2 mov.w #CCIS0+CM0+CAP,&CCTL2 ; Define CCR2,CAP,ACLK
Test_DCO bit.w #CCIFG,&CCTL2 ; Test capture flag
jz Test_DCO ;
bic.w #CCIFG,&CCTL2 ; Clear capture flag
;
AdjDCO mov.w &CCR2,R14 ; R14 = captured SMCLK
sub.w R15,R14 ; R14 = capture difference
mov.w &CCR2,R15 ; R15 = captured SMCLK
cmp.w #Delta,R14 ; Delta = SMCLK/(32768/8)
jlo IncDCO ;
jeq DoneDCO ;
DecDCO dec.b &DCOCTL ; Slow DCO with DCO and MOD
jnz Test_DCO ; Slower?
bit.b #07h,&BCSCTL1 ; Can RSEL.x be decremented?
jz DoneDCO ; jmp>DCO at slowest setting
dec.b &BCSCTL1 ; Decrement RSEL.x
jmp Test_DCO ;
IncDCO inc.b &DCOCTL ; Speed DCO with DCO and MOD
jnc Test_DCO ; Faster?
cmp.b #07h,&BCSCTL1 ; Can RSEL.x be increased?
jz DoneDCO ; jmp> DCO at fastest settting
inc.b &BCSCTL1 ; Increment RSEL.x
jmp Test_DCO ;
DoneDCO clr.w &CCTL2 ; Stop CCR2
ret ; Return from subroutine
;
;-----------------------------------------------------------------------------
; Interrupt Vectors Used MSP430x11x1
;-----------------------------------------------------------------------------
ORG 0FFFEh ; MSP430 RESET Vector
DW RESET ;
ORG 0FFF2h ; Timer_A0 Vector
DW TA0_ISR ;
END
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