RS-232 - Computer Busses - page 235

(a) 8232 (b) 8086

(c) 8088 (d) 8250

13.6.17 Which register is used to determine the status of the RS-232 connection:

(a) LSR (b) LCR

(c) STATUS (d) TD/RD buffer

13.6.18 Which register is used to configure the RS-232 connection:

(a) LSR (b) LCR

(c) STATUS (d) TD/RD buffer

13.6.19 Write a program that continuously sends the character 'A' to the serial line. Ob-

serve the output on an oscilloscope and identify the bit pattern and the baud rate.

13.6.20 Write a program that continuously sends the characters from 'A' to 'Z' to the se-

rial line. Observe the output on an oscilloscope.

13.6.21 Modify Program 13.2 so that the program prompts the user for the baud rate when

the program is started. A sample run is shown in Sample run 13.1.

Sample run 13.1
Enter baud rate required:
1 110 2 150 3 300 4 600

5 1200 6 2400 7 4800 8 9600
>> 8
RS232 transmission set to 9600 baud

13.6.22 Complete Table 13.6 to give the actual time to send 1000 characters for the given

baud rates. Compare these values with estimated values.

Note that approximately 10 bits are used for each character thus 960 characters
per second will be transmitted at 9600 baud.

Table 13.6 Baud rate divisors

Baud
rate

Time to send 1000 characters (s)

110

300

600

1200

2400

4800

9600

19200

13.6.23 Modify the setup_serial() routine so that the RS232 parameters can be passed
to it. These parameters should include the comport (either COM1: or COM2 :), the