- 2076 Baisakh · 2 marks
Port 3 of 8051
Short answer
Port 3 is an 8-bit bidirectional I/O with internal pull-ups. Each pin has an alternate function: P3.0 (RXD), P3.1 (TXD) serial, P3.2 (INT0), P3.3 (INT1) interupts, P3.4 (T0), P3.5 (T1) timer inputs, P3.6 (WR) and P3.7 (RD) exteranal memory strobes. Write 1 to read input.
Explain about PORT 3 of 8051 microcontroller.
Port 3 (P3.0-P3.7, pins 10-17) is an 8-bit bidirectional I/O port with internal pull-ups. Besides general I/O, every pin has a special alternate function that is used when the corresponding feature is enabled:
| Pin | Alternate function |
|---|---|
| P3.0 | RXD, serial input |
| P3.1 | TXD, serial output |
| P3.2 | INT0, external interrupt 0 |
| P3.3 | INT1, external interrupt 1 |
| P3.4 | T0, Timer 0 external input |
| P3.5 | T1, Timer 1 external input |
| P3.6 | WR, external data memory write |
| P3.7 | RD, external data memory read |
To use a pin as an input, 1 must be written to it first.
✓ Answer checked by Claude Opus 5.5 (high effort)
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