The 8x930Hx USB hub peripheral controller is based on the MCS 251 microcontroller. It consists of standard 8XC251Sx peripherals plus a USB module. The USB module provides both USB hub and USB embedded function capabilities. The 8x930Hx supports USB hub functionality, embedded function, suspend/resume modes, isochronous/non-isochronous transfers, and it is fully USB rev 1.0 specification compliant. The USB module contains one internal and three (or four) external downstream ports and integrates the USB transceivers, serial bus interface engine (SIE), hub interface unit (HIU), function interface unit (FIU), and transmit/receive FIFOs. The 8x930Hx uses the standard instruction set of the MCS 251 architecture, which is binary code compatible with the MCS 51 architecture.

■ USB Hub with One Upstream, One Internal Downstream, and Three External Downstream Ports on HD/HE Parts or Four on HF/HG Parts
    — Complete Universal Serial Bus Specification 1.0 Compatibility
    — Serves as both USB Hub and USB Embedded Function (Internal Port)
■ USB Hub
    — Connectivity Management
    — Downstream Device Connect/Disconnect Detection
    — Power Management, Including Suspend and Resume
    — Bus Fault Detection and Recovery
    — Full and Low Speed Downstream Device Support
■ Output Pin for Port Power Switching
■ Input Pin for Overcurrent Detection
■ USB Embedded Function
    — Supports Isochronous and Non-isochronous Data
■ On-chip USB Transceivers
■ Serial Bus Interface Engine (SIE)
    — Packet Decoding/Generation
    — CRC Generation and Checking
    — NRZI Encoding/Decoding and Bit-stuffing
■ Hub FIFO Data Buffers
    — One Pair of 16-byte Transmit and Receive FIFOs
    — One 1-byte Transmit Register
■ Embedded Function FIFO Data Buffers
    — Three Pairs of 16-byte Transmit and Receive FIFOs
    — One Pair of Configurable Transmit and Receive FIFOs (1 Kbyte total)
■ Automatic Transmit/Receive FIFO Management
■ Three USB Interrupt Vectors
    — Endpoint Transmit/Receive Done
    — Start of Frame/Hub Endpoint Done
    — Global Suspend/Resume
■ Low Clock Mode
■ User-selectable Configurations
    — External Wait State
    — External Address Range
    — Page Mode
■ Real-time Wait Function
■ 256-Kbyte External Code/Data Memory Space
■ On-chip ROM Options
    — 0, 8, or 16 Kbytes
■ 1024 bytes On-chip Data RAM
■ Four Input/Output Ports
■ Standard MCS® 51 UART
■ Power-saving Idle and Powerdown Modes
■ Register-based MCS® 251 Architecture
■ Code-compatible with MCS 51 and MCS 251 Microcontrollers
■ 12-MHz Crystal Operation