Hello Guys I have a bunch of ATMEL AT89C51RD2-CM date code 0306. I am trying to use the hardware SPI with no luck. According to the combined AT89C51RD2/AT89C51ED2 datasheet, this device has an SPI Interface.

The code below works on the AT89C51ED2, but not on the AT89C51RD2. In the code, I have simulated a CS line that goes low just before the SPI data is sent.I checked with a logic analyzer, there is no activity on any of the pins except the simulated CS line. I was wondering if the datasheet might be wrong? (After all, there ARE other mistakes in this datasheet!!)

I am well aware that the older (Temic) T89C51RD2 devices do not have an SPI interface.

I can always bit-bang the data but I was hoping to use the hardware interface.

Anyone know whether or not the datasheet is wrong? I find it hard to believe that every single one of my AT89C51RD2's are defective.

;this code is working for the AT89C51ED2 but not the AT89C51RD2.

	mov SPCON,#10010110b	; Fclk Periph/128, Master Mode, SPI Mode 3
;	mov SPCON,#10110101b	; same as above except Fclk Periph/64

	orl SPCON,#40h		; start spi
	mov	r7,#0		; start data @ 00h          

loop:             		
	mov SPI_Temp,r7		;
	lcall	SendSPI		;	
	lcall	Delay1mS

	inc	r7		;send 0h - 0FFh to SPI
	mov	a,r7
	jnz	loop

	xrl SPCON,#40h		; disable spi

stop:
	sjmp	stop
;
;send SPI data from SPI_Temp, returns read SPI data in SPI_Temp
SendSPI:
	clr	P1.0		;trigger for Logic Analyzer
	mov SPDAT,SPI_Temp	;transmit SPI Data

WaitSPI:
	mov a,SPSTA
	jnb acc.7,WaitSPI	;wait for TX complete before reading

	mov SPI_Temp,SPDAT	;read SPI Data
	setb	P1.0		;trigger for Logic Analyzer
	ret