8251A USART – Datasheet

The 8251 MegaCore function provides an interface between a microprocessor and a serial communications channel. The 8251 receives and transmits data in a variety of configurations including 7- or 8-bit data words, with odd, even, or no parity and 1 or 2 stop bits.

8251 Pinout

8251 Pin Configuration

Pin Number	Pin Name	Description
1	D2	Data Bit 2
2	D3	Data Bit 3
3	RX	Receive
4	GND	Ground
5	D4	Data Bit 4
6	D5	Data Bit 5
7	D6	Data Bit 6
8	D7	Data Bit 7
9	TXC	Transmit Clock Input (Active Low)
10	WR	Write (Active Low)
11	CS	Chip Select (Active Low)
12	C/D	Command/Data Select
13	RD	Read (Active Low)
14	RXRDY	Read Register Ready
15	TXRDY	Transmitter Register Ready
16	SYNDET/BD	See Data Sheet
17	CTS	Clear To Send (Active Low)
18	TXEMPTY	Transmitter Register Empty
19	TXD	Transmit Output
20	CLK	Clock
21	RESET	Reset
22	DSR	Data Set Ready (Active Low)
23	RTS	Request to Send (Active Low)
24	DTR	Data Terminal Ready (Active Low)
25	RXC	Receive Clock (Active Low)
26	Vcc	Positive Supply
27	D0	Data Bit 0
28	D1	Data Bit 1

8251 Key Features

• 8251 MegaCore function that provides an interface between a microprocessor and a serial communication channel
• Optimized for FLEX architecture
• Programmable word length, stop bits, and parity
• Offers divide-by-1, -16, or -64 mode
• Supports synchronous and asynchronous operation

You can download this datasheet for 8251A USART – Datasheet from the link given below: