M68HC08 datasheet(186/332 Pages) FREESCALE

186 / 332 page

Universal Serial Bus Module (USB)

Technical Data

MC68HC908JB16 — Rev. 1.1

186

Universal Serial Bus Module (USB)

Freescale Semiconductor

To enable the next data packet transmission, TX2E also must be set.

If the TXD2F bit is not cleared, a NAK handshake will be returned in

the next IN transaction.

Reset clears this bit. Writing to TXD2F has no effect.

1 = Transmit on endpoint 2 has occurred

0 = Transmit on endpoint 2 has not occurred

RXD2F — Endpoint 2 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 RXD2FR bit after all of

the received data has been read. Software also must set the RX2E bit

to 1 to enable the next data packet reception. If the RXD2F bit is not

cleared, a NAK handshake will be returned in the next OUT

transaction.

Reset clears this bit. Writing to RXD2F has no effect.

1 = Receive on endpoint 2 has occurred

0 = Receive on endpoint 2 has not occurred

TXD1F — Endpoint 1 Data Transmit Flag

This read-only bit is set after the data stored in the endpoint 1 transmit

buffer 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 TXD1FR bit. To

enable the next data packet transmission, TX1E also must be set. If

the TXD1F bit is not cleared, a NAK handshake will be returned in the

next IN transaction.

Reset clears this bit. Writing to TXD1F has no effect.

1 = Transmit on endpoint 1has occurred

0 = Transmit on endpoint 1has not occurred

RESUMF — Resume Flag

This read-only bit is set when USB bus activity is detected while the

SUSPND bit is set. Software must clear this flag by writing a logic 1 to

the RESUMFR bit. Reset clears this bit. Writing a logic 0 to RESUMF

has no effect.

1 = USB bus activity has been detected

0 = No USB bus activity has been detected

M68HC08 Datasheet(PDF) 186 Page - Freescale Semiconductor, Inc