SH7203 Datasheet, PDF (1224/1686 Pages) Renesas Technology Corp – 32-Bit RISC Microcomputer SuperHTM RISC engine Family / SH7200 Series

Section 23 USB 2.0 Host/Function Module (USB)
(f) Buffer Memory Operation (Continuous Transfer Setting)
Either the continuous transfer mode or the non-continuous transfer mode can be selected, using the
CNTMD bit in DCPCFG and PIPEnCFG. This selection is valid for PIPE0 to PIPE5.
The continuous transfer mode function is a function that sends and receives multiple transactions
in succession. When the continuous transfer mode is set, data can be transferred without interrupts
being issued to the CPU, up to the buffer sizes assigned for each of the pipes.
In the continuous sending mode, the data being written is divided into packets of the maximum
packet size and sent. If the data being sent is less than the buffer size (short packet, or the integer
multiple of the maximum packet size is less than the buffer size), BVAL = 1 must be set after the
data being sent has been written.
In the continuous reception mode, interrupts are not issued during reception of packets up to the
buffer size, until the transaction counter has ended, or a short packet is received.
Figure 23.11 shows an example of buffer memory operation for this module.
CNTMD = 0
When packet is received
CNTMD = 1
When packet is received
Max Packet Size
Unused area
Interrupt issued
Max Packet Size
Max Packet Size
CNTMD = 0
When packet is sent
CNTMD = 1
When packet is sent
Interrupt issued
Max Packet Size
Max Packet Size
Unused area
Transmission
enabled
Max Packet Size
Transmission
enabled
Figure 23.11 Example of Buffer Memory Operation
Rev. 2.00 Apr. 16, 2008 Page 1194 of 1652
REJ09B0313-0200