SH7205 Datasheet, PDF (1325/1904 Pages) Renesas Technology Corp – Renesas 32-Bit RISC Microcomputer SuperHTM RISC engine Family / SH7200 Series

Section 24 USB 2.0 Host/Function Module (USB)
(b) Interval Counter Initialization when the Function Controller Function is Selected
This module initializes the interval counter under the following conditions.
• Power-on reset
The IITV bit is initialized.
• Buffer memory initialization using the ACLRM bit
The IITV bits are not initialized but the count value is. Setting the ACLRM bit to 0 starts
counting from the value set in the IITV bits.
After the interval counter has been initialized, the counter is started under the following conditions
1 or 2 when a packet has been transferred normally.
1. An SOF is received following transmission of data in response to an IN token, in the PID =
BUF state.
2. An SOF is received after data following an OUT token is received in the PID = BUF state.
The interval counter is not initialized under the conditions noted below.
1. When the PID bit is set to NAK or STALL
The interval timer does not stop. This module attempts the transactions at the subsequent
interval.
2. The USB bus reset or the USB is suspended
The IITV bit is not initialized. When the SOF has been received, the counter is restarted from
the value prior to the reception of the SOF.
(2) Setup of Data to be Transmitted using Isochronous Transfer when the Function
Controller Function is Selected
With isochronous data transmission using this module in function controller function, after data
has been written to the buffer memory, a data packet can be sent with the next frame in which an
SOF packet is detected. This function is called the isochronous transfer transmission data setup
function, and it makes it possible to designate the frame from which transmission began.
If a double buffer is used for the buffer memory, transmission will be enabled for only one of the
two buffers even after the writing of data to both buffers has been completed, that buffer memory
being the one to which the data writing was completed first. For this reason, even if multiple IN
tokens are received, the only buffer memory that can be sent is one packet's worth of data.
Rev. 1.00 Mar. 25, 2008 Page 1293 of 1868
REJ09B0372-0100