Datasheet

135
4235K–8051–05/08
AT89C51RD2/ED2
Features .................................................................................................... 1
1 Description ............................................................................................... 2
2 Block Diagram .......................................................................................... 3
3 SFR Mapping ............................................................................................ 4
4 Pin Configurations ................................................................................... 9
5 Port Types .............................................................................................. 14
6 Oscillator ................................................................................................ 15
6.1 Registers .........................................................................................................15
6.2 Functional Block Diagram ................................................................................16
7 Enhanced Features ................................................................................ 17
7.1 X2 Feature .......................................................................................................17
8 Dual Data Pointer Register (DPTR) ...................................................... 21
9 Expanded RAM (XRAM) ......................................................................... 23
9.1 Registers .........................................................................................................24
10 Reset ....................................................................................................... 26
10.1 Introduction ......................................................................................................26
10.2 Reset Input ......................................................................................................26
10.3 Reset Output ...................................................................................................26
11 Power Monitor ........................................................................................ 28
11.1 Description .......................................................................................................28
12 Timer 2 .................................................................................................... 30
12.1 Auto-reload Mode ............................................................................................30
12.2 Programmable Clock-output ............................................................................31
12.3 Registers .........................................................................................................32
13 Programmable Counter Array (PCA) .................................................... 35
13.1 PCA Capture Mode .........................................................................................43
13.2 16-bit Software Timer/ Compare Mode ...........................................................43
13.3 High Speed Output Mode ................................................................................44
13.4 Pulse Width Modulator Mode ..........................................................................45
13.5 PCA Watchdog Timer ......................................................................................46