Features of 8251A (USART)

Features of 8251A (USART)

1. The Intel 8251A is an universal synchronous and asynchronous communication controller.

2. It supports standard asynchronous protocol with :

a) 5 to 8 Bit character format

b) odd, even or no parity generation and detection

c) Baud rate from DC to 19.2 Kbaud

d) False start bit detection

e) Automatic break detect and handling

f) Break character generation.

3. It has built in baud rate generator.

4. It supports standard synchronous protocol with :

a) 5 to 8 Bit character format

b) Internal or external character synchronization

c) Automatic sync insertion

d) Baud rate from DC to 64 Kbaud

5. It allows full duplex transmission and reception.

6. It provides double buffering of data both in the transmission section and in the receiver section.

7. It provides error detection logic, which detects parity, overrun and framing errors.

8. It has Modem Control Logic, which supports basic data set control signals.

9. It provides separate clock inputs for receiver and transmitter sections, thus providing an option of fixing different baud rates for the transmitter and receiver section.

10. It is compatible with an extended range of Intel microprocessors.

11. It is fabricated in 28 pin DIP package and its all inputs and outputs are TTL compatible.

12. It is available in standard as well as extended temperature range.

Review Questions

1. Explain the advantages of using the following chip in microprocessor based systems : USART.

AU : May-04, Marks 5

2. Bring about the features of 8251.

 AU : Dec.-05, Marks 4