This program assembles ok but it does not seem to run properly on the evaluation board. I get a constant 5 volts out of the Txd pin on the board. When i run it througth the simm and configure the serial to go out to the com1 port instead of the screen, i can see the 3 channels on the scope. Any help would be appreciated.
;=============================================================
; Program Name : testrun4.asm
;
; Detailed Description of Application: This program will read three separate ; analog inputs from an accelerometer and input them into the ADuC812 to do ; an analog to digital conversion then output the signal to a radio after ; processing
;
; Author: Lance Fleming
;
; Hardware Notes:
; Analog Devices ADuC812 with an 8052 compatible core
; 11.0592 MHz internal Oscillator
;=============================================================

$MOD52

; VARIABLE DECLARATIONS

Chx DATA 030h ; X channel stored in address 30 hex
Chy DATA 031h ; Y channel stored in address 31 hex
Chz DATA 032h ; Z channel stored in address 32 hex
Chksum DATA 033h ; check sum stored in address 33 hex

Tchx DATA 034H ; temporary storage of offset values plus
Tchy DATA 035H
Tchz DATA 036H

; START OF PROGRAM

org 000h ; Execution Starts Here
mov 0EFH,#0C0H ; set adccon1 register to enable A/D conversion
; and the timing of the A/D
setb F0 ; flag for first time through loop set

; INITILIAZATION OF STACK POINTER ?

mov SP,#02fh


LOOP: ; start of loop


; SELECTION OF THE X CHANNEL
mov 0D8H,#010H ; set adccon2 register for reading of channel 0(x)
JB 0D8H.4, $ ; wait for A/D conversion
mov Chx,0D9H ; store result of conversion

; check if this is the first time through and if it is goto the next channel

JB F0,therex
mov A,Chx
subb A,Tchx
add A,#128
mov Chx,A
therex:

; SELECTION OF THE Y CHANNEL

mov 0D8H,#011h ; set adccon2 register for reading of channel 1(y)
JB 0D8h.4, $ ; wait for A/D conversion
mov Chy,0D9H ; store result of conversion

; check if this is the first time through and if it is goto the next channel

JB F0,therey
mov A,Chy
subb A,Tchy
add A,#128
mov Chy,A
therey:

; SELECTION OF THE Z CHANNEL

mov 0D8H,#012h ; set adccon2 register for reading of channel 2(z)
JB 0D8h.4,$ ; wait for A/D conversion
mov Chz,0D9H ; store result of conversion

; check if this is the first time through and if it is goto temporary variables

JB F0,therez
mov A,Chz
subb A,Tchz
add A,#128
mov Chz,A
therez:

; if first time through, store data in temporary variables and set first flag

JNB F0,first
mov Tchx,Chx
mov Tchy,Chy
mov Tchz,Chz
first:
clr F0 ;Set flag to 0 for not first time through

; calculate the checksum

mov A,Chx
add A,Chy
add A,Chz
mov Chksum,A

; configure serial port for transmission and its baud rate

; mov SCON,#00h
setb SM1 ; 8 bit UART mode
clr SM2 ; disable multiprocessor communication
mov TMOD,#20h ; 8bit timer auto-reload mode
mov PCON,#00h ; make sure that PCON.7 is not set for double baud rate
; calculate baud, value of TH1=256-((clock/384)/baud)
; =256-((11059200/384)/4800)
; =250
mov TH1,#250 ; 4800 baud rate
setb TR1 ; start timer for serial communication
; NOTE: to set to 9600 baud, set the SMOD bit in the PCON SFR(PCON.7)

; SERIAL OUT X DATA

clr TI ; be sure end of transmit flag is set to 0
clr REN ; make sure no receiving during transmission
mov SBUF,#Chx ; output x data
JNB TI, $

; SERIAL OUT Y DATA
clr TI ; be sure end of transmit flag is set to 0
clr REN ; make sure no receiving during transmission
mov SBUF,#Chy ; output y data
JNB TI, $ ; pause until transmit complete

; SERIAL OUT Z DATA
clr TI ; be sure end of transmit flag is set to 0
clr REN ; make sure no receiving during transmission
mov SBUF,#Chz ; output z data
JNB TI, $ ; pause until transmit complete


LJMP LOOP ; back to beginning of loop

; Subroutines
; [Put in Subroutine Code]


end ; end of program