\ name : msp430FR5xxx_I2C_Master.asm
\
-\ Copyright (C) <2016> <J.M. THOORENS>
-\
-\ This program is free software: you can redistribute it and/or modify
-\ it under the terms of the GNU General Public License as published by
-\ the Free Software Foundation, either version 3 of the License, or
-\ (at your option) any later version.
-\
-\ This program is distributed in the hope that it will be useful,
-\ but WITHOUT ANY WARRANTY; without even the implied warranty of
-\ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
-\ GNU General Public License for more details.
-\
-\ You should have received a copy of the GNU General Public License
-\ along with this program. If not, see <http://www.gnu.org/licenses/>.
-\
-\
\ I2C MASTER Standard Mode software driver without interrupt
\ Target: MSP-EXP430FR5969 @ 8,16MHz
\ version 1.1 2016-03-18
-\ ----------------------------------\
-ASM I2C_M \
-\ ----------------------------------\
-\ \ in I2CS_ADR/I2CM_BUF as RX/TX buffer requested by I2CS_ADR(0(0))
-\ \ I2CS_ADR(0) = I2C_Slave_addr&R/w
-\ \ I2CM_BUF(0) = TX/RX count of datas
-\ \ I2CM_BUF(0) = 0 ==> send only I2C address
-\ \ used S = BUF ptr
-\ \ T
-\ \ out I2CSLA_ADR & (R/W) unCHNGd
-\ \ S = BUF PTR pointing on first data not exCHNGd
-\ \ T = count of TX/RX datas exCHNGd
-\ \ T = -1 ==> NACK on address
-\ \ I2CS_ADR(0) = unCHNGd
-\ \ I2CM_BUF(0) = unCHNGd
-BIS #1,&UCB0CTLW0 \ SWRST
-MOV #$0FD3,&UCB0CTLW0 \ master mode + UCTR + START + SWRST, IFG=IE=0
-MOV #$00C8,&UCB0CTLW1 \ set automatic stop (count byte reached)
-MOV #$14,&UCB0BRW \ baudrate = SMCLK/20 = 400 kHz @8MHz ; 340 kHz measured
-MOV #I2CM_BUF,S \ count & TX buf
-MOV.B @S+,&UCB0TBCNT \
-CMP.B #0,&UCB0TBCNT \
-0= IF \ count = 0
- BIS #4,&UCB0CTLW0 \ add Stop cmd to Start cmd ==> Master send only I2C address
-THEN
-MOV #I2CS_ADR,T \ I2Cadr & RX buf
-MOV.B @T+,&UCB0I2CSA \ UCB0I2CSA = slave_address & R/w bit
-RRA &UCB0I2CSA \ UCB0I2CSA = slave_address, C flag = R/w flag
-U>= IF \ C flag = 1
- MOV T,S \ Master read : S = RX buffer
- BIC #$10,&UCB0CTLW0 \ UCB0CTLW0 <-- UCTR=0
-THEN \
-\ ------------------------------ \
-\ Start \
-\ ------------------------------ \
-MOV.B #-1,T \ T=-1
-BIC #1,&UCB0CTLW0 \ UCB0CTLW0 : clear SWRST, start I2C MASTER
-BIT.B #1,&I2CS_ADR \ R/W test
-0= IF \
-\ ---------------------------- \
-\ MASTER TX \
-\ ---------------------------- \
- BEGIN \
- MOV.B &UCBCNT0,T \ store count of byte
- BIT #8,&UCB0IFG \ test UCSTPIFG
- 0<> IF \
- MOV @RSP+,PC \ end of I2C_M TX driver
- THEN \
- BIT #$20,&UCB0IFG \ test UCNACKIFG
- 0<> IF \
- BIS #4,&UCB0CTLW0 \ generate stop bit
- MOV @RSP+,PC \ end of I2C_M TX driver
- THEN \
- BIT #2,&UCB0IFG \ test UCTXIFG0
- 0<> IF \
- MOV.B @S+,&UCB0TXBUF \ load data into UCB0TXBUF
- THEN \
- AGAIN \
-THEN \
-\ ------------------------------ \
-\ MASTER RX \
-\ ------------------------------ \
-BEGIN \ of Master RX
- MOV.B &UCBCNT0,T \ store count of byte
- BIT #8,&UCB0IFG \ test UCSTPIFG
- 0<> IF \
- MOV @RSP+,PC \ end of I2C_M RX driver
- THEN \
- BIT #1,&UCB0IFG \ test UCRXIFG0
- 0<> IF \
- MOV.B &UCB0RXBUF,0(S) \ load data from UCB0RXBUF
- ADD #1,S \
- THEN \
-AGAIN \
-ENDASM \ 62 words + 9 init words
- \
+\ \ ----------------------------------\
+\ ASM I2C_M \
+\ \ ----------------------------------\
+\ \ \ in I2CS_ADR/I2CM_BUF as RX/TX buffer requested by I2CS_ADR(0(0))
+\ \ \ I2CS_ADR(0) = I2C_Slave_addr&R/w
+\ \ \ I2CM_BUF(0) = TX/RX count of datas
+\ \ \ I2CM_BUF(0) = 0 ==> send only I2C address
+\ \ \ used S = BUF ptr
+\ \ \ T
+\ \ \ out I2CSLA_ADR & (R/W) unCHNGd
+\ \ \ S = BUF PTR pointing on first data not exCHNGd
+\ \ \ T = count of TX/RX datas exCHNGd
+\ \ \ T = -1 ==> NACK on address
+\ \ \ I2CS_ADR(0) = unCHNGd
+\ \ \ I2CM_BUF(0) = unCHNGd
+\ BIS #1,&UCB0CTLW0 \ SWRST
+\ MOV #$0FD3,&UCB0CTLW0 \ master mode + UCTR + START + SWRST, IFG=IE=0
+\ MOV #$00C8,&UCB0CTLW1 \ set automatic stop (count byte reached)
+\ MOV #$14,&UCB0BRW \ baudrate = SMCLK/20 = 400 kHz @8MHz ; 340 kHz measured
+\ MOV #I2CM_BUF,S \ count & TX buf
+\ MOV.B @S+,&UCB0TBCNT \
+\ CMP.B #0,&UCB0TBCNT \
+\ 0= IF \ count = 0
+\ BIS #4,&UCB0CTLW0 \ add Stop cmd to Start cmd ==> Master send only I2C address
+\ THEN
+\ MOV #I2CS_ADR,T \ I2Cadr & RX buf
+\ MOV.B @T+,&UCB0I2CSA \ UCB0I2CSA = slave_address & R/w bit
+\ RRA &UCB0I2CSA \ UCB0I2CSA = slave_address, C flag = R/w flag
+\ U>= IF \ C flag = 1
+\ MOV T,S \ Master read : S = RX buffer
+\ BIC #$10,&UCB0CTLW0 \ UCB0CTLW0 <-- UCTR=0
+\ THEN \
+\ \ ------------------------------ \
+\ \ Start \
+\ \ ------------------------------ \
+\ MOV.B #-1,T \ T=-1
+\ BIC #1,&UCB0CTLW0 \ UCB0CTLW0 : clear SWRST, start I2C MASTER
+\ BIT.B #1,&I2CS_ADR \ R/W test
+\ 0= IF \
+\ \ ---------------------------- \
+\ \ MASTER TX \
+\ \ ---------------------------- \
+\ BEGIN \
+\ MOV.B &UCBCNT0,T \ store count of byte
+\ BIT #8,&UCB0IFG \ test UCSTPIFG
+\ 0<> IF \
+\ MOV @RSP+,PC \ end of I2C_M TX driver
+\ THEN \
+\ BIT #$20,&UCB0IFG \ test UCNACKIFG
+\ 0<> IF \
+\ BIS #4,&UCB0CTLW0 \ generate stop bit
+\ MOV @RSP+,PC \ end of I2C_M TX driver
+\ THEN \
+\ BIT #2,&UCB0IFG \ test UCTXIFG0
+\ 0<> IF \
+\ MOV.B @S+,&UCB0TXBUF \ load data into UCB0TXBUF
+\ THEN \
+\ AGAIN \
+\ THEN \
+\ \ ------------------------------ \
+\ \ MASTER RX \
+\ \ ------------------------------ \
+\ BEGIN \ of Master RX
+\ MOV.B &UCBCNT0,T \ store count of byte
+\ BIT #8,&UCB0IFG \ test UCSTPIFG
+\ 0<> IF \
+\ MOV @RSP+,PC \ end of I2C_M RX driver
+\ THEN \
+\ BIT #1,&UCB0IFG \ test UCRXIFG0
+\ 0<> IF \
+\ MOV.B &UCB0RXBUF,0(S) \ load data from UCB0RXBUF
+\ ADD #1,S \
+\ THEN \
+\ AGAIN \
+\ ENDASM \ 62 words + 9 init words
+\ \
+
+\ ------------------------------\
+ASM I2C_M \
+\ ------------------------------\
+\ \ in I2CS_ADR(S) = -4(S) = I2C address
+\ \ I2CS_CNT(S) = -2(S) = count of data to be exchanged
+\ \ 0(S) = data1
+\ \ 1(S) = data2...
+\ \ used S = BUF ptr, W
+\ \ out I2CS_EXG(S) = -1(S) = count of bytes exchanged
+\
+BIS #1,&UCB0CTLW0 \ SWRST
+MOV #$0FD3,&UCB0CTLW0 \ master mode + UCTR + START + SWRST, IFG=IE=0
+MOV #$00C8,&UCB0CTLW1 \ set automatic stop (count byte reached)
+FREQ_KHZ @ 16000 = \ 16 MHz or 8 MHz ?
+[IF] \ if 16 MHz
+ MOV #$40,&UCB0BRW \ baudrate = SMCLK/40 = 400 kHz @16MHz ; 340 kHz measured
+[ELSE] \ if 8 MHz
+ MOV #$20,&UCB0BRW \ baudrate = SMCLK/20 = 400 kHz @8MHz ; 340 kHz measured
+[THEN] \
+MOV.B I2C_CNT(S),W \ W = count of data
+CMP.B #0,W \
+0= IF \ if count = 0
+ BIS #4,&UCB0CTLW0 \ add Stop cmd ==> Master send only I2C address then STOP (doesn't work with MASTER RX!)
+THEN \
+MOV.B W,&UCB0TBCNT \ set threshold byte count to generate automatic STOP
+MOV.B I2C_ADR(S),W \ 3 W = slave_address & R/w bit
+RRA.B W \ 1 C flag = R/w bit
+U>= IF \ if read
+ BIC #$10,&UCB0CTLW0 \ UCB0CTLW0 <-- UCTR=0
+THEN \
+MOV W,&UCB0I2CSA \ 3 UCB0I2CSA = slave_address
+MOV.B #0,W \ clear buffer pointer
+\ ------------------------------\
+BIC #1,&UCB0CTLW0 \ UCB0CTLW0 : clear SWRST ==> start I2C MASTER
+\ ------------------------------\
+BW2 \
+BIT #$20,&UCB0IFG \ test Nack flag UCNACKIFG (on address | on TX data) from slave
+0<> IF \
+ BIS #4,&UCB0CTLW0 \ generate STOP
+ CMP.B #0,W \ Nack on TX data ?
+ 0<> IF \ yes
+ SUB.B #1,W \ remove this TX data from count
+ THEN \
+ GOTO BW2 \
+THEN \
+BIT #8,&UCB0IFG \ test stop flag UCSTPIFG
+0<> IF \
+ MOV.B W,I2C_EXG(S) \ store count of bytes
+ BIS #1,&UCB0CTLW0 \ SWRST
+ RET \ ===================> end of I2C_M driver
+THEN \
+BIT #2,&UCB0IFG \ test TX flag UCTXIFG0
+0<> IF \
+\ ----------------------------\
+\ MASTER TX \
+\ ----------------------------\
+ MOV.B I2C_BUF(W),&UCB0TXBUF \ load byte into UCB0TXBUF
+ ADD.B #1,W \
+ GOTO BW2 \
+THEN \
+BIT #1,&UCB0IFG \ test RX flag UCRXIFG0
+0<> IF \
+\ ----------------------------\
+\ MASTER RX \
+\ ----------------------------\
+ MOV.B &UCB0RXBUF,I2C_BUF(W) \ load byte from UCB0RXBUF
+ ADD.B #1,W \
+THEN
+GOTO BW2 \
+ENDASM \ 64 words
\ ------------------------------\
CODE START \ init
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