Document
W921E880A/W921C880
4-BIT MICROCONTROLLER
Table of Contents-
1. GENERAL DESCRIPTION .........................................................................................................................3 2. FEATURES.................................................................................................................................................3 3. PIN CONFIGURATION ...............................................................................................................................6 4. PIN DESCRIPTION.....................................................................................................................................7 5. BLOCK DIAGRAM ......................................................................................................................................9 6. FUNCTIONAL DESCRIPTION .................................................................................................................10
6.1 ROM Memory Map .........................................................................................................................10 6.2 RAM Memory Map..........................................................................................................................11
6.2.1 Special Control Reg. Area..................................................................................................11 6.2.2 Stack Reg. Area.................................................................................................................12 6.2.3 Working Reg. Area ............................................................................................................12 6.3 Internal Oscillator Circuit .................................................................................................................13 6.4 Initial State ......................................................................................................................................14 6.5 Input/Output ....................................................................................................................................14 6.5.1 I/O Pull High and Open Drain Control.................................................................................17 6.6 Serial Port.......................................................................................................................................19 6.7 DTMF Generator.............................................................................................................................21 6.8 Beep Tone Generator.....................................................................................................................22 6.9 8-bit D/A Converter.........................................................................................................................23 6.10 Comparator...................................................................................................................................24 6.11 Timer 0−3......................................................................................................................................25 6.11.1 Arbitrary Waveform Generator.........................................................................................32 6.12 Interrupt.........................................................................................................................................33 6.12.1 Interrupt Control Register ..................................................................................................33 6.12.2 Interrupt Enable Flag........................................................................................................34 6.13 Operating Mode............................................................................................................................34 6.14 Initial Condition Register of EPROM Program Method .................................................................39 6.15 Reset ............................................................................................................................................39
Publication Release Date: July 1999 - 1 - Revision A3
W921E880A/W921C880
7. ADDRESSING MODE ..............................................................................................................................40 7.1 ROM Addressing Mode ..................................................................................................................40 7.2 RAM Addressing Mode...................................................................................................................40 7.3 Look-up Table Addressing Mode (1 Word/2 Cycles) ......................................................................42
8. SPECIAL CONTROL REG. FORMAT ......................................................................................................43 9. INSTRUCTION MAP.......................................................................................................................