📄 slavuart.asm
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;====================================================================
;
; Author : ADI - Apps
;
; Date : October 2003
;
; File : SLAVuart.asm
;
; Hardware : ADuC842
;
; Description : This slave program transmits the numbers 11-20 in
; binary form continuously down the SPI serial port
; after receiving a clock signal.
;
; After the transmission of each byte the incoming
; byte is saved in order at an internal RAM address
; between #40h and #50h.
;
; This program can be used with the master program
; MASTuart.asm (which generates a clock signal for
; the slave)
;
; After the 16 input bytes have been stored in memory
; the values in memory are outputted up the UART to
; the PC where they can be viewed on screen by a
; program such as Hyperterminal. After each
; transmission up the UART the program is delayed for
; 1s before returning from the interrupt. It then
; waits for the next data byte from the SPI port
; which will arrive about 4s later if used with the
; Master program (MASTuart.asm).
;
; The Slave program (SLAVuart.asm) should be started
; after the master program (MASTuart.asm) but within
; the time delay of 2s in order that the slave
; program is synchronised by the first outputted
; clock of the master.
;
; The clock is inputted at sclock (pin 26)
; The data is outputted at MISO (pin 14)
; The data is inputted at sdata/MOSI (pin 27)
;====================================================================
;
$MOD842 ;Use 8052 predefined Symbols
LED EQU P3.4
FLAG BIT 00H
;____________________________________________________________________
; BEGINNING OF CODE
CSEG
ORG 0000H
JMP MAIN
;____________________________________________________________________
; SPI INTERRUPT ROUTINE
ORG 003BH
CLR FLAG ; Clear flag to leave LOOP2
MOV @R1, SPIDAT ; move input into memory
INC R1 ; increment memory location so new
; data is stored in new address
CJNE R1, #50H, CONT ; reset memory location to 40h when
; memory location reaches 50h saving
; 16 bytes of data
CALL SNDUART
CONT: RETI
;====================================================================
ORG 0060H ; Start code at address above interrupts
MAIN: ; Main program
MOV PLLCON,#03H
MOV T3CON,#083h
MOV T3FD,#02Dh
MOV SCON,#052h
MOV SPICON,#24h ; Initialise SPICON to have
; -Enable SPI serial port
; -slave mode select
; -CPOL=0, clk idling low
; -CPHA=1
; note: it is important to have CPHA in the master and the slave
; program equal, otherwise uncertainty will exist, as the input
; will be measued during its change of state, and not is at
; its final value.
MOV IEIP2, #01h ; Enable SPI interrupt
SETB EA ; Enable interrupts
MOV R1, #40h ; initialise R1 to 40 to store the
; input data from memory location 40
MOV R0, #0AH ; initialise R0 to 10
TRNSMT:
INC R0
MOV SPIDAT, R0 ; transmit the current value on R0
SETB FLAG ; set flag so that we wait here until
; the spi interrupt routine clears
; the FLAG
JB FLAG, $ ; stay here until flag is cleared
; by interrupt
; check if R0 is equal to 20. If so the number 20 has been
; transmitted and we should reset R0 to 10 to start transmission
; from 11 again.
MOV A, R0
CJNE A, #14H, TRNSMT ; if R0 is not 20, jump to TRNSMT
MOV R0, #0AH ; if R0=20 make R0=10 & jump to TRNSMT
JMP TRNSMT
; Transmit the values in locations 40h->50h up the UART wait for
; 1 seconds and then transmit and receive values to/from the Master
; again down the SPI port.
SNDUART:
CPL LED ;CPL LED with each transmission
MOV DPTR, #TITLE
CALL SENDSTRING ; write title block on screen
MOV R1, #40h ; move value at address 40 into R2
MOV A, @R1
MOV R2, A
NEXT: ; Put new value on a new line
MOV A, #10 ; Transmit a linefeed (= ASCII 10)
CALL SENDCHAR
MOV A, #13 ;Transmit a carriage return (=ASCII 13)
CALL SENDCHAR
MOV A, R2 ; Transmit R2 i.e. value @ address R1
CALL SENDVAL
INC R1 ; Increment address
MOV A, @R1
MOV R2, A ; R2 holds the value @ addrR1
MOV A, R1 ; Check if at address 50h
CJNE A, #50h, NEXT ; if not jump to Next
JMP WAIT1S ; if so wait 1s and repeat
WAIT1S: MOV A, #100 ; wait for time less than master to
; synchronise with the master
CALL DELAY
MOV R1, #40h ; store new inputs at address 40h again
RET
;____________________________________________________________________
; SENDSTRING
SENDSTRING: ; sends ASCII string to UART starting at location
; DPTR and ending with a null (0) value
PUSH ACC
PUSH B
CLR A
MOV B,A
IO0010: MOV A,B
INC B
MOVC A,@A+DPTR
JZ IO0020
CALL SENDCHAR
JMP IO0010
IO0020: POP B
POP ACC
RET
;____________________________________________________________________
; SENDCHAR
SENDCHAR: ; sends ASCII value contained in A to UART
JNB TI,$ ; wait til present char gone
CLR TI ; must clear TI
MOV SBUF,A
RET
;____________________________________________________________________
; SENDVAL
SENDVAL: ; converts the hex value of A into two ASCII chars,
; and then spits these two characters up the UART.
; does not change the value of A.
PUSH ACC
SWAP A
CALL HEX2ASCII
CALL SENDCHAR ; send high nibble
POP ACC
PUSH ACC
CALL HEX2ASCII
CALL SENDCHAR ; send low nibble
POP ACC
RET
;____________________________________________________________________
; HEX2ASCII
HEX2ASCII: ; converts A into the hex character representing the
; value of A's least significant nibble
ANL A,#00Fh
CJNE A,#00Ah,$+3
JC IO0030
ADD A,#007h
IO0030: ADD A,#'0'
RET
;____________________________________________________________________
; DELAY
DELAY: ; Delays by 10ms * A
;
MOV R2,A ; Acc holds delay variable
DLY0: MOV R3,#01Bh ; Set up delay loop0
DLY1: MOV R4,#0FFh ; Set up delay loop1
DJNZ R4,$ ; Dec R4 & Jump here until R4 is 0
;
DJNZ R3,DLY1 ; Dec R3 & Jump DLY1 until R3 is 0
;
DJNZ R2,DLY0 ; Dec R2 & Jump DLY0 until R2 is 0
; wait for ACC*100ms
RET ; Return from subroutine
;____________________________________________________________________
TITLE: DB 10,10,13,'____________________________________',10,13
DB 'Analog Devices MicroConverter ADuC832',10,13
DB ' SPI SLAVE Demo Routine',10,13
DB ' Data Stored in Memory in Hex Form',10,13,0
;____________________________________________________________________
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