ST72P623 View Datasheet(PDF) - STMicroelectronics

Part Name

Description

Manufacturer

ST72P623

LOW SPEED USB 8-BIT MCU WITH 3 ENDPOINTS, FLASH OR ROM MEMORY, LVD, WDG, 10-BIT ADC, 2 TIMERS, SCI, SPI

STMicroelectronics 

ST7262xxx

10.6 USB INTERFACE (USB)

10.6.1 Introduction

For general information on the USB, refer to the

The USB Interface implements a low-speed func-

tion interface between the USB and the ST7 mi-

“Universal Serial Bus Specifications” document

available at http//:www.usb.org.

crocontroller. It is a highly integrated circuit which Serial Interface Engine

includes the transceiver, 3.3 voltage regulator, SIE The SIE (Serial Interface Engine) interfaces with

and DMA. No external components are needed the USB, via the transceiver.

apart from the external pull-up on USBDM for low

speed recognition by the USB host. The use of The SIE processes tokens, handles data transmis-

DMA architecture allows the endpoint definition to sion/reception, and handshaking as required by

be completely flexible. Endpoints can be config- the USB standard. It also performs frame format-

ured by software as in or out.

) 10.6.2 Main Features

t(s ■ USB Specification Version 1.1 Compliant

c ■ Supports Low-Speed USB Protocol

u ■ Two or Three Endpoints (including default one)

d depending on the device (see device feature list

ro and register map)

P ■ CRC generation/checking, NRZI encoding/

decoding and bit-stuffing

te ■ USB Suspend/Resume operations

le ■ DMA Data transfers

so ■ On-Chip 3.3V Regulator

b ■ On-Chip USB Transceiver

O 10.6.3 Functional Description

) - The block diagram in Figure 50, gives an overview

t(s of the USB interface hardware.

ting, including CRC generation and checking.

Endpoints

The Endpoint registers indicate if the microcon-

troller is ready to transmit/receive, and how many

bytes need to be transmitted.

DMA

When a token for a valid Endpoint is recognized by

the USB interface, the related data transfer takes

place, using DMA. At the end of the transaction, an

interrupt is generated.

Interrupts

By reading the Interrupt Status register, applica-

tion software can know which USB event has oc-

curred.

duc Figure 50. USB Block Diagram

6 MHz

te Pro ENDPOINT

le REGISTERS

CPU

Obso USBDM

Transceiver

SIE

DMA

Address,

USBDP

data buses

and interrupts

USBVCC

3.3V

Voltage

Regulator

INTERRUPT

REGISTERS

MEMORY

USBGND

Doc ID 6996 Rev 5

83/139

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