ST7263 STMICROELECTRONICS [STMicroelectronics], ST7263 Datasheet - Page 65

• Manufacturer Part Number: ST7263
• Description: LOW SPEED USB 8-BIT MCU FAMILY with up to 16K MEMORY, up to 512 BYTES RAM, 8-BIT ADC, WDG, TIMER, SCI & I2C
• Manufacturer: STMICROELECTRONICS [STMicroelectronics]

5.6 USB INTERFACE (USB)
5.6.1 Introduction
The USB Interface implements a low-speed func-
tion interface between the USB and the ST7 mi-
crocontroller. It is a highly integrated circuit which
includes the transceiver, 3.3 voltage regulator, SIE
and DMA. No external components are needed
apart from the external pull-up on USBDM for low
speed recognition by the USB host. The use of
DMA architecture allows the endpoint definition to
be completely flexible. Endpoints can be config-
ured by software as in or out.
5.6.2 Main Features
5.6.3 Functional Description
The block diagram in
of the USB interface hardware.
Figure 36. USB Block Diagram
USBGND
USBVCC
USBDM
USB Specification Version 1.1 Compliant
Supports Low-Speed USB Protocol
Two or Three Endpoints (including default one)
depending on the device (see device feature list
and register map)
CRC generation/checking, NRZI encoding/
decoding and bit-stuffing
USB Suspend/Resume operations
DMA Data transfers
On-Chip 3.3V Regulator
On-Chip USB Transceiver
USBDP
Transceiver
Figure
Voltage
Regulator
3.3V
1, gives an overview
SIE
6 MHz
For general information on the USB, refer to the
“Universal Serial Bus Specifications” document
available at http//:www.usb.org.
Serial Interface Engine
The SIE (Serial Interface Engine) interfaces with
the USB, via the transceiver.
The SIE processes tokens, handles data transmis-
sion/reception, and handshaking as required by
the USB standard. It also performs frame format-
ting, including CRC generation and checking.
Endpoints
The Endpoint registers indicate if the microcontrol-
ler 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.
REGISTERS
INTERRUPT
REGISTERS
ENDPOINT
DMA
Address,
data buses
and interrupts
MEMORY
CPU
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