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16 usbep1 receive data size register (usbepsz1), 17 usb trigger register (usbtrg) – Renesas SH7641 User Manual

Page 809

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Section 20 USB Function Module

Rev. 4.00 Sep. 14, 2005 Page 759 of 982

REJ09B0023-0400

20.3.16 USBEP1

Receive

Data Size Register (USBEPSZ1)

USBEPSZ1 indicates, in bytes, the amount of data received from the host by endpoint 1. The
endpoint 1 FIFO buffer has a dual-FIFO configuration. The receive data size indicated by this
register refers to the currently selected FIFO (that can be read by CPU).

USBEPSZ1 can be initialized to H'00 by a power-on reset.

Bit Bit

Name

Initial
Value R/W Description

7 to 0

All 0

R

Number of bytes received by endpoint 1

20.3.17 USB Trigger Register (USBTRG)

USBTRG generates one-shot triggers to control the transmit/receive sequence for each endpoint.

USBTRG can be initialized to H'00 by a power-on reset.

Bit Bit

Name

Initial
Value R/W Description

7

 0

R

Reserved

This bit is always read as 0. The write value should
always be 0.

6

EP3PKTE

0

W

EP3 Packet Enable

After one packet of data has been written to the
endpoint 3 transmit FIFO buffer, the transmit data is
fixed by writing 1 to this bit.

5

EP1RDFN

0

W

EP1 Read Complete

Write 1 to this bit after one packet of data has been
read from the endpoint 1 FIFO buffer. The endpoint 1
receive FIFO buffer has a dual-FIFO configuration.
Writing 1 to this bit initializes the FIFO that was read,
enabling the next packet to be received.

4

EP2PKTE

0

W

EP2 Packet Enable

After one packet of data has been written to the
endpoint 2 FIFO buffer, the transmit data is fixed by
writing 1 to this bit.

3

 0

R

Reserved

The write value should always be 0.

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