
W921E880A/W921C880
4-BIT MICROCONTROLLER
Publication Release Date: September 1998
- 1 -
Revision A2
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 ........................................................................................................................................13
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