68HC705JB2 datasheet(87/128 Pages) NXP

87 / 128 page

August 28, 1998

GENERAL RELEASE SPECIFICATION

UNIVERSAL SERIAL BUS MODULE

REV 1.1

10-19

10.5.1 USB Address Register (UADDR)

USBEN — USB Module Enable

This read/write bit enables and disables the USB module and the USB pins.

When USBEN is clear, the USB module will not respond to any tokens. Reset

clears this bit.

1 =

USB function enabled

0 =

USB function disabled

UADD6-UADD0 — USB Function Address

These bits specify the USB address of the device. Reset clears these bits.

10.5.2 USB Interrupt Register 0 (UIR0)

TXD0F — Endpoint 0 Data Transmit Flag

This read only bit is set after the data stored in Endpoint 0 transmit buffers has

been sent and an ACK handshake packet from the host is received. Once the

next set of data is ready in the transmit buffers, software must clear this ﬂag by

writing a logic 1 to the TXD0FR bit. To enable the next data packet

transmission, TX0E must also be set. If TXD0F bit is not cleared, a NAK

handshake will be returned in the next IN transaction.

Reset clears this bit. Writing a logic 0 to TXD0F has no effect.

1 =

Transmit on Endpoint 0 has occurred

0 =

Transmit on Endpoint 0 has not occurred

RXD0F — Endpoint 0 Data Receive Flag

This read only bit is set after the USB module has received a data packet and

responded with an ACK handshake packet. Software must clear this ﬂag by

writing a logic 1 to the RXD0FR bit after all of the received data has been read.

Software must also set RX0E bit to one to enable the next data packet

reception. If RXD0F bit is not cleared, a NAK handshake will be returned in the

next OUT transaction.

Reset clears this bit. Writing a logic 0 to RXD0F has no effect.

Bit 7

Bit 6

Bit 5

Bit 4

Bit 3

Bit 2

Bit 1

Bit 0

UADDR

USBEN

UADD6

UADD5

UADD4

UADD3

UADD2

UADD1

UADD0

$0038

reset

⇒

00000000

Figure 10-20. USB Address Register (UADDR)

Bit 7

Bit 6

Bit 5

Bit 4

Bit 3

Bit 2

Bit 1

Bit 0

UIR0

TXD0F

RXD0F

RSTF

SUSPND

TXD0IE

RXD0IE

$0039

TXD0FR

RXD0FR

reset

⇒

00000000

= Unimplemented

Figure 10-21. USB Interrupt Register 0 (UIR0)

Freescale Semiconductor, Inc.

For More Information On This Product,

Go to: www.freescale.com

68HC705JB2 Datasheet(PDF) 87 Page - NXP Semiconductors

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