ST7SCR datasheet(50/101 Pages) STMICROELECTRONICS

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ST7SCR

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USB INTERFACE (Cont’d)

DEVICE ADDRESS REGISTER (DADDR)

Read/Write

Reset Value: 0000 0000 (00h)

Bit 7 = Reserved, forced by hardware to 0.

Bits 6:0 = ADD[6:0] Device address, 7 bits.

Software must write into this register the address

sent by the host during enumeration.

Note: This register is also reset when a USB reset

is received or forced through bit FRES in the US-

BCTLR register.

USB STATUS REGISTER (USBSR)

Read only

Reset Value: 0000 0000 (00h)

Bits 7:6 = PID[1:0] Token PID bits 1 & 0 for End-

point 0 Control.

USB token PIDs are encoded in four bits. PID[1:0]

correspond to the most significant bits of the PID

field of the last token PID received by Endpoint 0.

Note: The least significant PID bits have a fixed

value of 01.

When a CTR interrupt occurs on Endpoint 0 (see

PID[1:0] bits to retrieve the PID name of the token

received.

The USB specification defines PID bits as:

Bit 5 = IN/OUT Last transaction direction for End-

point 1, 2 , 3, 4 or 5.

This bit is set by hardware when a CTR interrupt

occurs on Endpoint 1, 2, 3, 4 or 5.

0: OUT transaction

1: IN transaction

Bits 4:3 = Reserved, forced by hardware to 0.

Bits 2:0 = EP[2:0] Endpoint number.

These bits identify the endpoint which required at-

tention.

000 = Endpoint 0

001 = Endpoint 1

010 = Endpoint 2

011 = Endpoint 3

100 = Endpoint 4

101 = Endpoint 5

ERROR STATUS REGISTER (ERRSR)

Read only

Reset Value: 0000 0000 (00h)

Bits 7:3 = Reserved, forced by hardware to 0.

Bits 2:0 = ERR[2:0] Error type.

These bits identify the type of error which oc-

curred.

Note: these bits are set by hardware when an er-

ror interrupt occurs and are reset automatically

when the error bit (USBISTR bit 4) is cleared by

software.

ADD6

ADD5

ADD4

ADD3

ADD2

ADD1

ADD0

PID1

PID0

IN/

OUT

EP2

EP1

EP0

PID1

PID0

PID Name

OUT

SETUP

ERR2

ERR1

ERR0

ERR2 ERR1 ERR0

Meaning

000

No error

Bitstuffing error

CRC error

011

EOP error (unexpected end of

packet or SE0 not followed by

J-state)

100

PID error (PID encoding error,

unexpected or unknown PID)

101

Memory over / underrun (mem-

ory controller has not an-

swered in time to a memory

data request)

111

Other error (wrong packet,

timeout error)

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