GENERAL DESCRIPTION
INTRODUCTION
The ST9216x family brings the enhanced ST9 register-based architecture to a new range of high performance microcontrollers specifically designed for USB (Universal Serial Bus) applications. Their performance derives from the use of a
flexible 256-register programming model for ultrafast context switching and real-time event response. The intelligent on-chip peripherals offload the ST9 core from I/O and data management processing tasks allowing critical application tasks to get the maximum use of core resources.

■ Internal Memories: 20 Kbytes ROM/EPROM/OTP, 2 Kbytes RAM
■ Register oriented 8/16 bit core
■ 224 general purpose registers available as RAM, accumulators or index pointers
■ Minimum instruction cycle time: 167 ns (@24 MHz CPU frequency)
■ Low power modes: WFI, SLOW, HALT and STOP
■ DMA controller for reduced processor overhead
■ Full speed USB interface with DMA, compliant with USB specifications version 1.1 (in normal voltage mode)
■ USB Embedded Functions with 16 fully configurable endpoints (buffer size programmable), supporting all USB data transfer types (Isochronous included)
■ On-chip USB transceiver and 3.3 voltage regulator
■ Multimaster I2C-bus serial interface up to 400KHz. with DMA capability
■ Serial Communications Interface (SCI) with DMA capability:
    – Asynchronous mode up to 315 Kb/s
    – Synchronous mode up to 3 MHz
■ External memory interface (8-bit data/16-bit address) with DMA capability from the USB
■ 16-bit Multi-Function Timer (12 operating modes) with DMA capability
■ 16-bit Timer with 8-bit prescaler and Watchdog
■ 6-channel, 8-bit A/D Converter (ADC)
■ 15 interrupt pins on 8 interrupt channels
■ 14 pins programmable as wake-up or additional external interrupts
■ 42 (DIP56) or 44 (QFP64) fully programmable I/Os with 6 or 8 high sink pads (10 mA @ 1 V)
■ Programmable PLL clock generator (RCCU) using a low frequency external quartz (8 MHz)
■ On-chip RC oscillator for low power operation
■ Low Voltage Detector Reset on some devices¹
■ Rich instruction set with 14 addressing modes
■ Several operating voltage modes available on some devices¹ :
    – Normal Voltage Mode
    – 8-MHz Low Voltage Mode
    – 16-MHz Low Voltage Mode
■ 0 - 24 MHz CPU clock operation @ 4.0-5.5 V (all devices)
■ 0 - 8 MHz CPU clock operation @ 3.0-4.0 V (8-MHz and 16-MHz Low Voltage devices)
■ 0 - 16 MHz CPU clock operation @ 3.0-4.0 V (16-MHz Low Voltage devices only)
■ Division-by-zero trap generation
■ 0^oC to 70^oC temperature range
■ Low EMI design supporting single sided PCB
■ Complete development tools, including assembler, linker, C-compiler, archiver, source level debugger and hardware emulators, and Real Time Operating System