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AN 114

Application Note

www.xicor.com

REV 1.1 11/12/02

;-----------------------------------------------------------------------------

;

; PUT MAIN PROGRAM HERE...

;

; Below are sample main programs calling the various command routines

;

;-----------------------------------------------------------------------------

main:

mov

SP, #STACK_TOP; Initialize stack pointer

;----------------------------------------------------------------------------

;

; The following section is required for the Cygnal processor. This could

; change for different versions of the 80C51.

;

; Disable the WDT. (IRQs not enabled at this point.)

; If interrupts were enabled, they would need to be explicitly disabled

; so that the 2nd move to WDTCN occurs no more than four clock

; cycles after the first move to WDTCN.

clr

EA

; Disable interupts

mov

WDTCN, #0DEh; Cygnal processor specific

mov

WDTCN, #0ADh; Cygnal processor specific

; Enable the Port I/O Crossbar

mov

XBR2, #40h

; Cygnal processor specific (enable weak pull ups)

mov

PRT1CF, #00h ; Cygnal processor specific

; Set no ports as push-pull (this processor

; operates from 3.3V, but the X9408 operates from

; 5V, so the 8051 outputs must be pulled up to 5V

; with external resistors.)

;-----------------------------------------------------------------------------

;

; The following are sample code segments for use in the main program...

; The potentiometer was A0-A3 pins were set to address 0Ch.

;

;-----------------------------------------------------------------------------

write_2_wcr:

mov

ADDR_BYTE, #SLAVE_ADR12; Load Slave address byte

mov

ID, #WCR_2

; Specify WCR for DCP#2

mov

COMMAND, #WRITEWCR; Write to WCR

mov

DATA_BYTE, #43; Set wiper position to tap 43

call

execute

read_from_wcr:

mov

ADDR_BYTE, #SLAVE_ADR12; Load Slave address byte

mov

ID, #WCR_2

; Specify WCR for DCP#2

mov

COMMAND, #READWCR; Read WCR

call

execute

; WCR value is in DATA_BYTE

write_2_dr:

mov

ADDR_BYTE, #SLAVE_ADR12; Load Slave address byte

mov

ID, #DCP2_R1; Specify DR#1 for DCP#2

mov

COMMAND, #WRITEDR; Write to DR

mov

DATA_BYTE, #21; Set data value to 21

call

execute