AR-B1474 User¡¦s Guide
9-3
(3) Send out one block data (Transmit – the data more than two characters)
Step 1: Enable TXC signal, and the bit 0 of the address of offset+4 just sets “ 1”.
Step 2: Send out the data. (Write all data to the offset+0 of the current COM port address)
Step 3: Wait for the buffer’ s data empty. Check transmitter holding register (THRE, bit 5 of the address of
offset+5), and transmitter shift register (TSRE, bit 6 of the address of offset+5) are all sets must be
“ 0” .
Step 4: Disabled TXC signal, and the bit 0 of the address of offset+4 sets “ 0”
(4) Receive data
The RS-485’ s operation of receiving data is in the same of the RS-232’ s.
(5) Basic Language Example
a.) Initial 86C450 UART
10 OPEN “ COM1:9600,m,8,1”AS #1 LEN=1
20 REM Reset DTR
30 OUT &H3FC, (INP(%H3FC) AND &HFA)
40 RETURN
b.) Send out one character to COM1
10 REM Enable transmitter by setting DTR ON
20 OUT &H3FC, (INP(&H3FC) OR &H01)
30 REM Send out one character
40 PRINT #1, OUTCHR$
50 REM Check transmitter holding register and shift register
60 IF ((INP(&H3FD) AND &H60) >0) THEN 60
70 REM Disable transmitter by resetting DTR
80 OUT &H3FC, (INP(&H3FC) AND &HEF)
90 RETURN
c.) Receive one character from COM1
10 REM Check COM1: receiver buffer
20 IF LOF(1)<256 THEN 70
30 REM Receiver buffer is empty
40 INPSTR$”
50 RETURN
60 REM Read one character from COM1: buffer
70 INPSTR$=INPUT$(1,#1)
80 RETURN
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