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Rev. 2.0, 09/99, page 234 of 364
17.4
Serial Bus Interface Unit (SIU)
The serial bus interface unit (SIU) manages communications between the SH3/SH4 CPU and the
USB host. It consists of the Serial Interface Engine (SIE) and the Serial Bus Manager (SBM). The
SIE handles the communication protocol of Universal Serial Bus while the SBM manages the
USB data that are received and transmitted by the HD64463 USB device.
17.4.1
Serial Bus Manager (SBM)
The Serial Bus Manager (SBM) manages data transactions between the CPU and the USB host.
This data transaction management is based on the transfer type and the state of the FIFOs. To be
more specific, the SBM monitors the transaction status, manages the FIFOs, and relays control
events to the CPU via interrupt requests.
Endpoint Configuration Register (EPCONx, x=0, 1, 2, 3)
Bit
7654321
0
Bit Name
SRE
STE
CE
SDM
RIE
RE
TOE
TE
R/W
Bit
Description
7
SRE: Stall Receive Endpoint. When this bit is set, the receive endpoint will return a stall handshake
to host when a valid OUT token has been received. When this bit is cleared, the stall handshake will
be disabled during reception.
6
STE: Stall Transmit Endpoint. When this bit is set, the transmit endpoint will return a stall handshake
to host when a valid IN token has been received. When this bit is cleared, the stall handshake will be
disabled during transmit.
5
CE: Control Endpoint. When this bit is set, the endpoint will be the control endpoint. For endpoint 0,
this bit is set to 1. But for other endpoints, this bit will be cleared to 0.
4
SDM: Single Data Set Mode. This bit is used to configure the receive/transmit endpoint for single
data packet operation. When this bit is set, the RXFIFO/TXFIFO single packet mode will be enabled.
This means that only a single data packet is allowed to reside in RXFIFO/TXFIFO. When this bit is
clear, the RXFIFO/TXFIFO operates in two data set mode and two data packets can reside in
RXFIFO/TXFIFO.
3
RIE: Receive Input Enable. This bit is used to enable data from the USB to be written into RXFIFO.
If disabled, the endpoint will not write the received data into RXFIFO, and at the end of reception, it
returns a NAK if SRE bit is cleared.
2
RE: Receive Endpoint Enable. This bit is used to enable the receive endpoint. When disabled, the
endpoint does not respond to OUT token.
1
TOE: Transmit Output Enable. This bit is used to enable data in TXFIFO to be transmitted. When
disabled, the endpoint returns a NAK to IN token if STE bit is cleared.
0
TE: Transmit Endpoint Enable. This bit is used to enable the transmit endpoint. When disabled, the
endpoint does not respond to IN token.