主程序中，单片机将标准串口设置为115200bps,将模拟串口设置为19200bps。单片机将标准串口收到的数据从模拟串口发送出去，将模拟串口接收到的数据从标准串口发送回来。

txd0_data:
ldi status,(1<
push temp
in temp,gimsk
cbr temp,(1< out gimsk,temp ;disable gimsk/int0
pop temp

ser bit_cnt ;bit_cnt=0xff
mov sbuf0,temp ;send data

ldi temp,(256-N)
out TCNT0,temp ;wait 1 bit timer0 interrupt

in temp,tifr
sbr temp,(1< out tifr,temp ;clr tifr/tov0

in temp,timsk
sbr temp,(1< out timsk,temp ;enable timsk/toie0

cbi portb,txd0 ;uart start

ret
;******************************************
rxd0_data:
sbrs status,fe0 ;if fe0=0 then exit
rjmp rxd0_data_end
cbr status,(1< mov temp,sbuf0
rxd0_data_end:
ret
;******************************************

;uart received a byts from uart and then return it from uart0:
;uart received a byts from uart0 and then return it from uart :
main:
sbic usr,rxc
rjmp send_115200

sbrs status,rdr
rjmp uart_end
send_19200:
rcall rxd0_data ;get uart data from 19200bps uart0

wait2: sbis usr,udrie
rjmp wait2
out udr,temp ;send data to 115200bps uart
rjmp uart_end

send_115200:
in temp,udr ;get uart data from 115200bps uart
sbic usr,fe
rjmp uart_end ;if fe err then end