Atmel

P89C51RD2 - 8 bit Microcontroller with 64k Bytes Flash Memory

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Features 80C51 CPU On-chip Flash Program Memory with In-System Programming Boot ROM contains Flash programming routines for downloading via UART 6/12 clocks per machine cycle Speed 20MHz/33MHz with 12 clocks per machine cycle Fully Static Operation RAM expandable externally to 64 kbytes Four Interrupt Priority Levels Seven Interrupt Sources Four 8-bit I/O ports Full-duplex enhanced UART Power Control Modes Programmable Clock Out Asynchronous Port Reset Programmable Counter Array 40-pin DIP

Pin Description Pin Number Description 1 Port 1.0/Timer 2 2 Port 1.1/Timer 2 3 Port 1.2/External Clock Input 4 Port 1.3/PCA Module 0 5 Port 1.4/PCA Module 1 6 Port 1.5/PCA Module 2 7 Port 1.6/PCA Module 3 8 Port 1.7/PCA Module 4 9 Reset 10 Port 3.0/Serial Input Port 11 Port 3.1/Serial Outpur Port 12 Port 3.2/External Interrupt 13 Port 3.3/External Interrupt 14 Port 3.4/Timer 0 External Input 15 Port 3.5/Timer 1 External Input 16 Port 3.6/External Data Memory Write 17 Port 3.7/External Data Memory Read 18 Crystal 2 19 Crystal 1 20 Ground 21 - 28 Port 2 29 Program Strobe Enable 30 Address Latch Enable 31 External Access Enable/Programming Supply 32 - 39 Port 0 40 Power Supply

Pin Layout Dimensional Drawing

Technical Data Data Sheet Philips - Data Sheet for P89C51RD2 Application Notes Philips - 80 Series Application Notes