M68HC08 datasheet(187/332 Pages) FREESCALE

187 / 332 page

Universal Serial Bus Module (USB)

MC68HC908JB16 — Rev. 1.1

Technical Data

Freescale Semiconductor

Universal Serial Bus Module (USB)

187

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 also must be set. If

the TXD0F bit is not cleared, a NAK handshake will be returned in the

next IN transaction.

Reset clears this bit. Writing 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 also must set the RX0E bit

to 1 to enable the next data packet reception. If the RXD0F bit is not

cleared, the USB will respond with a NAK handshake to any

endpoint 0 OUT tokens; but does not respond to a SETUP token.

Reset clears this bit. Writing to RXD0F has no effect.

1 = Receive on endpoint 0 has occurred

0 = Receive on endpoint 0 has not occurred

M68HC08 Datasheet(PDF) 187 Page - Freescale Semiconductor, Inc