INTRODUCTION
The ST72321R, ST72321AR and ST72321J devices are members of the ST7 microcontroller family designed for mid-range applications All devices are based on a common industry standard 8-bit core, featuring an enhanced instruction set and are available with FLASH or ROM program memory.
Under software control, all devices can be placed in WAIT, SLOW, ACTIVE-HALT or HALT mode, reducing power consumption when the application is in idle or stand-by state.

■ Memories
   – 32K to 60K dual voltage High Density Flash (HDFlash) or ROM with read-out protection capability.
    In-Application Programming and In-Circuit Programming for HDFlash devices
   – 1K to 2K RAM
   – HDFlash endurance: 100 cycles, data retention: 20 years at 55°C
■ Clock, Reset And Supply Management
   – Enhanced low voltage supervisor (LVD) for main supply and auxiliary voltage detector (AVD) with interrupt capability
   – Clock sources: crystal/ceramic resonator os cillators, internal RC oscillator, clock security system and bypass for external clock
   – PLL for 2x frequency multiplication
   – Four Power Saving Modes: Halt, Active-Halt, Wait and Slow
■ Interrupt Management
   – Nested interrupt controller
   – 14 interrupt vectors plus TRAP and RESET
   – Top Level Interrupt (TLI) pin on 64-pin devices
   – 15 external interrupt lines (on 4 vectors)
■ Up to 48 I/O Ports
   – 48/32 multifunctional bidirectional I/O lines
   – 34/22 alternate function lines
   – 16/12 high sink outputs
■ 5 Timers
   – Main Clock Controller with: Real time base, Beep and Clock-out capabilities
   – Configurable watchdog timer
   – Two 16-bit timers with: 2 input captures, 2 output compares, external clock input on one timer, PWM and pulse generator modes
   – 8-bit PWM Auto-reload timer with: 2 input captures, 4 PWM outputs, output compare and time base interrupt, external clock with event detector
■ 3 Communications Interfaces
   – SPI synchronous serial interface
   – SCI asynchronous serial interface (LIN compatible)
   – I2C multimaster interface
■ 1 Analog peripheral
   – 10-bit ADC with up to 16 input pins
■ Instruction Set
   – 8-bit Data Manipulation
   – 63 Basic Instructions
   – 17 main Addressing Modes
   – 8 x 8 Unsigned Multiply Instruction
■ Development Tools
   – Full hardware/software development package
   – In-Circuit Testing capability