Single-chip 8-bit microcontroller

The P80C557E4/P83C557E4/P89C557E4 (hereafter generically referred to as P8xC557E4) single-chip 8-bit microcontroller is manufactured in an advanced CMOS process and is a derivative of the 80C51 microcontroller family. The P8xC557E4 has the same instruction set as the 80C51. Three versions of the derivative exist:

• P83C557E4 - 32 Kbytes mask programmable ROM
• P80C557E4 - ROMless version of the P83C557E4
• P89C557E4 - 32 Kbytes FEEPROM (Flash-EEPROM)

The P8xC557E4 contains a non-volatile 32 Kbytes mask programmable ROM (P83C557E4) or electrically erasable FEEPROM respectively (P89C557E4), a volatile 1024 ? 8 read/write data memory, five 8-bit I/O ports, one 8-bit input port, two 16-bit timer/event counters (identical to the timers of the 80C51), an additional 16-bit timer coupled to capture and compare latches, a 15-source, two-priority-level, nested interrupt structure, an 8-input ADC, a dual DAC pulse width modulated interface, two serial interfaces (UART and I²C-bus), a "watchdog" timer, an on-chip oscillator and timing circuits. For systems that require extra capability the P8xC557E4 can be expanded using standard TTL compatible memories and logic.

In addition, the P8xC557E4 has two software selectable modes of power reduction - Idle Mode and power-down mode. The Idle Mode freezes the CPU while allowing the RAM, timers, serial ports, and interrupt system to continue functioning. The power-down mode saves the RAM contents but freezes the oscillator, causing all other chip functions to be inoperative.

The device also functions as an arithmetic processor having facilities for both binary and BCD arithmetic as well as bit-handling capabilities. The instruction set consists of over 100 instructions: 49 one-byte, 45 two-byte, and 17 three- byte. With a 16 MHz system clock, 58% of the instructions are executed in 0.75 µs and 40% in 1.5 µs. Multiply and divide instructions require 3 µs.