PRODUCT OVERVIEW

Introduction

The Parallax SX family of configurable communications controllers is fabricated in an advanced CMOS process technology. The advanced process, combined with a RISC-like architecture, allows high-speed computation, flexible I/O control, and efficient data manipulation. Throughput is enhanced by operating the device at frequencies up to 75 MHz and by optimizing the instruction set to include mostly single-cycle instructions. The deterministic architecture of the SX provides reliable performance for time-critical applications. In addition, the SX architecture is flash-based and therefore reprogrammable. On-chip functions include a generalpurpose 8-bit timer with prescaler, an analog comparator, a brown-out detector, a watchdog timer, a power-save mode with multi-source wakeup capability, an internal R/C oscillator, user-selectable clock modes, and highcurrent outputs. These features enable the SX to be used as a general-purpose, high-speed microcontroller in a variety of applications.

Key Features

75 MIPS Performance

• SX20AC/SX28AC: DC - 75 MHz

• SX20AC/SX28AC: as low as 13.3 ns instruction cycle, 39.9 ns internal interrupt response

• 1 instruction per clock for most instructions (skips require 2 clocks, branches require 3 clocks, IREAD requires 4) EE/FLASH Program Memory and SRAM Data Memory

• Access time of < 13.3 ns provides single cycle access

• EE/Flash rated for > 10,000 rewrite cycles

• 2048 Words EE/Flash program memory

• 136x8 bits SRAM data memory

CPU Features

• Compact, RISC-like instruction set

• All non-branch instructions are single cycle

• Eight-level push/pop hardware stack for subroutine operation

• Fast table lookup capability through run-time readable code (IREAD instruction)

• Totally predictable program execution rate for precise real-time applications Fast and Deterministic Interrupt

• Jitter-free 3-cycle internal interrupt response

• Hardware context save/restore of key resources such as PC, W, STATUS, and FSR within the 3-cycle interrupt response time

• External wakeup/interrupt capability on Port B (8 pins)

Flexible I/O

• All port pins individually programmable as I/O

• Inputs are TTL or CMOS level selectable

• All pins have selectable internal pull-ups

• Selectable Schmitt Trigger inputs on Ports B and C

• All output pins capable of sourcing/sinking 30 mA

• Port A outputs have symmetrical drive

• Analog comparator support on Port B (RB0 OUT, RB1 IN-, RB2 IN+)

• Selectable I/O operation synchronous to the oscillator clock

Hardware Peripheral Features

• One 8-bit Real Time Clock/Counter (RTCC) with programmable 8-bit prescaler

• Watchdog Timer (shares the RTCC prescaler)

• Analog comparator

• Brown-out detector

• Multi-Input Wakeup logic on 8 pins

• Internal RC oscillator with configurable rate from 31.25 kHz to 4 MHz

• Power-On-Reset

Packages

• 20-pin SSOP, 28-pin DIP/SSOP Programming and Debugging Support

• On-chip in-system serial programming support via the oscillator pins

• On-chip in-system debugging support logic

• Real-time emulation, full program debug, and integrated development environment offered by the

Parallax SX-Key® programming device

• The language options available: Parallax Assembly; Parallax SX/B (BASIC); and CCS SX/C (C)

Software Support

• Native assembly instruction set

• Expanded assembly instruction set available in the SASM assembler of the Parallax SX-Key IDE

• Parallax SX/B compiler (BASIC)

• Several “C” compliers available from third-party vendors