3.2.2 Auxiliary RAM..................................................................................................... 52
3.2.3 External RAM...................................................................................................... 53
3.2.4 Special Function Register for RAM..................................................................... 53
Chapter 4 Configurable I/O Ports..................................................59
4.1 I/O Port Configurations......................................................................... 59
4.1.1 Quasi-bidirectional I/O......................................................................................... 59
4.1.2 Push-pull Output.................................................................................................. 60
4.1.3 Input-only Mode................................................................................................... 60
4.1.4 Open-drain Output................................................................................................ 60
4.2 I/O Port Registers ................................................................................ 61
4.3 I/O port application Notes.................................................................... 63
4.4 I/O port application.............................................................................. 63
4.4.1 Typical transistor control circuit........................................................................... 63
4.4.2 Typical diode control circuit................................................................................ 63
4.4.3 3V/5V hybrid system.......................................................................................... 64
4.4.4 How to make IO port low after MCU reset......................................................... 64
4.4.5 I/O drive LED application circuit....................................................................... 64
4.4.6 I/O immediately drive LED application circuit.................................................. 66
Chapter 5 Instruction System........................................................67
5.1 Special Function Registers.................................................................... 67
5.2 Addressing Modes............................................................................... 72
5.3 Instruction Set Summary....................................................................... 73
5.4 Instruction Definitions.......................................................................... 78
Chapter 6 Interrupt...................................................................... 115
6.1 Interrupt Structure................................................................................116
6.2 Interrupt Register.................................................................................117
6.3 Interrupt Priorities............................................................................. 121
6.4 How Interrupts Are Handled.............................................................. 121
6.5 External Interrupts............................................................................. 122
6.6 Response Time.................................................................................. 125
Chapter 7 Timer/Counter 0/1.......................................................126
7.1 Timer/Counter 0 Mode of Operation................................................. 128
7.2 Timer/Counter 1 Mode of Operation................................................. 131
7.3 Baud Rate Generator and Programmable Clock Output on P1.0........ 134
