Thắc mắc về giao tiếp SPI

[trangham283]

Cảm ơn mọi người đã giúp mình trả lời những câu hỏi trên. Hic hic đây là code mình viết, mình dùng UART để kiểm tra xem việc đọc/viết dữ liệu nhưng vẫn không thành công.

Mình trước đó đã có một code riêng để kiểm tra UART, nên mình khá chắc chắn vấn đề nằm ở cái SPI này...

Các cao thủ có thể nhìn qua code này rồi giúp em được không ạ? Cảm ơn mọi người nhiều nhiều!

;Instruction shortcuts:
.equ 	RDINS,3
.equ	WRINS,2
.equ	WRDI,4
.equ	WREN,6
.equ	RDSR,5
.equ	WRSR,1


ADDR:		.space 2				;Current Memory address
TOSEND:		.space 2
NUM:		.space 2

RDATA:		.space 2
OUTWORD:	.space 2




call	_spi_init

mov		#0xFFFF,W0
mov		W0,NUM

;WREN:
call	cslow
mov		#WREN,W0
mov		W0,OUTWORD
call	output
call	cshigh

call	cslow
mov		#WRINS,W0
mov		W0,OUTWORD
call 	output

;Write address:
mov		ADDR,W0				;MSB of address
swap	W0
mov		W0,OUTWORD
call	output

mov		ADDR,W0				;LSB of address
mov		W0,OUTWORD
call	output

;Write data
mov 	NUM,W0				;This would write only LSB
mov		W0,OUTWORD
call	output
call 	cshigh


;Polling:
poll:
call	cslow
mov		#RDSR,W0
mov		W0,OUTWORD
call	output
mov		#0x0000,W0			;Dummy send to read
mov		W0,OUTWORD
call	output
mov		RDATA,W0
and		#0x0001,W0			;Is WIP bit clear?
bra		nz,poll
call	cshigh

send:
clr		ADDR

memrd1:

call	cslow
mov		#RDINS,W0
mov		W0,OUTWORD
call	output

;Write address:
mov		ADDR,W0				;address MSB
swap	W0
mov		W0,OUTWORD
call	output

mov		ADDR,W0				;address LSB
mov		W0,OUTWORD
call	output

mov		#0x00,W0			;Dummy write to retain clock
mov		W0,OUTWORD	
call	output
call	cshigh

mov		RDATA,W0
mov		W0,TOSEND

;Send to PC via UART

call	chktr	
mov		TOSEND,W0
mov		W0,U1TXREG
swap	        W0
call	        chktr
mov		W0,U1TXREG

done:
bra		done
;..............................................................................
;Subroutine: SPI Initialization
;..............................................................................
_spi_init:
mov		#0x013E,W0			;SS not used anyway
							;SDO pin controlled by module
                                ;Communication byte-wide
				;Input sampled at middle of data output line
				;CKE = 1: Output data changes on transition from CLK active to idle
				;CKP = 0: Idle state for CLK at low level
			        ;Master enable, scale: fsck = fcy/4	= 1MHz

mov		W0,SPI1CON
bclr	SPI1STAT,#SPIROV
bset	SPI1STAT,#SPIEN
clr		ADDR						;Set first memory address to write to: 0x0000
return

;Sending instructions to EEPROM
output:
mov		OUTWORD,W8
mov		W8,SPI1BUF

chktrans:							;Is transmit buffer empty??
mov		SPI1STAT,W2
and		#0x0002,W2
bra		nz,chktrans

chkrd:
mov		SPI1STAT,W2
and		#0x0001,W2					;Is receive buffer full?
bra		z,chkrd


mov		SPI1BUF,W8					;Dump received data
mov		W8,RDATA
bclr	SPI1STAT,#SPIROV

return

cslow:
bclr	PORTB,#RB2
return

cshigh:
bset	PORTB,#RB2
return

chktr:
;Check if UART transmit buffer is full
mov		U1STA,W2
and		#0x0200,W2
bra		nz,chktr
return