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MC68681

Dual asynchronous receiver/transmitter (DUART)

MC68681
Category: Communication | Datasheet

The MC68681 dual universal asynchronous receiver/transmitter (DUART) is part of the M68000 Family of peripherals and directly interfaces to the MC68000 processor via an asynchronous bus structure. The MC68681 consists of eight major sections: internal control logic, timing logic, interrupt control logic, a bidirectional 8-bit data bus buffer, two independent communication channels (A and B), a 6-bit parallel input port, and an 8-bit parallel output port.

Pinout

Pin Signal Dir Name
1 RS1 Input Register-Select Bus Bit 4
2 IP3 Input Parallel Input 3
3 RS2 Input Register-Select Bus Bit 2
4 IP1 Input Parallel Input 1
5 RS3 Input Register-Select Bus Bit 3
6 RS4 Input Register-Select Bus Bit 4
7 IP0 Input Parallel Input 0
8 R/W# Input Read/Write
9 DTACK# Output (OC) Data Transfer Acknowledge
10 RxDB Output Channel B Receiver Serial Data
11 TxDB Output Channel B Transmitter Serial Data
12 OP1 Output Parallel Output 1
13 OP3 Output Parallel Output 3
14 OP5 Output Parallel Output 5
15 OP7 Output Parallel Output 7
16 D1 Input/Output Bidirectional-Data Bus Bit 1
17 D3 Input/Output Bidirectional-Data Bus Bit 3
18 D5 Input/Output Bidirectional-Data Bus Bit 5
19 D7 Input/Output Bidirectional-Data Bus Bit 7
20 GND Power Ground
21 IRQ# Output (OC) Interrupt Request
22 D6 Input/Output Bidirectional-Data Bus Bit 6
23 D4 Input/Output Bidirectional-Data Bus Bit 4
24 D2 Input/Output Bidirectional-Data Bus Bit 2
25 D0 Input/Output Bidirectional-Data Bus Bit 0
26 OP6 Output Parallel Output 6
27 OP4 Output Parallel Output 4
28 OP2 Output Parallel Output 2
29 OP0 Output Parallel Output 0
30 TxDA Output Channel A Transmitter Serial Data
31 RxDA Input Channel A Receiver Serial Data
32 X1/CLK Input Crystal Input or External Clock
33 X2 Input Crystal Input
34 RESET# Input Reset
35 CS# Input Chip Select
36 IP2 Input Parallel Input 2
37 IACK# Input Interrupt Acknowledge
38 IP5 Input Parallel Input 5
39 IP4 Input Parallel Input 4
40 VCC Power Power Supply (+5V)