R8A66597BG RENESAS [Renesas Technology Corp], R8A66597BG Datasheet - Page 152

• Manufacturer Part Number: R8A66597BG
• Description: ASSP (USB2.0 2 Port Host/1 Port Peripheral Controller)
• Manufacturer: RENESAS [Renesas Technology Corp]

R8A66597FP/DFP/BG
3.9.5
R e v 1 . 0 1
Buffer A
Buffer B
Isochronous Transfer Send Buffer Flush when Peripheral Controller function is selected
(1) Successful transfer
(2) Damaged token
(3) Packet insertion
(4) Frame miss (1)
(5) Frame miss (2)
(6) Delayed token
When the Peripheral Controller function is selected, if the controller does not receive an IN token in the interval frame
in the isochronous data send but receives the (µ) SOF packet in the next frame, the IN token is handled as a corrupted
token and the buffer that is send-enabled is cleared set to the write-enabled status.
At this time, if the double-buffer is used and the write event to both buffers is complete, the cleared buffer memory is
assumed to be sent in the interval frame, and the other side buffer memory is set to the transfer-enabled status at the
received the next (u) SOF packet.
The operation start timing of the buffer flush function differs according to the value set in the IITV bit, as follows.
Figure 3.21 provides an operation example of the controller buffer flush function. When a token is received outside of
the specified interval period (before the interval frame), a written data packet or a zero-length packet is sent as an
underrun error according to the data setup status
Figure 3.22 shows an example of an interval error generated in the controller. There are 5 types of interval errors, as
listed below. Timing 1 in the figure shows when the interval error occurs and how the buffer flush function operates.
When an interval error occurs during an IN transfer, the buffer flush function goes into operation; during an OUT
transfer, the NRDY interrupt is generated.
Use the OVRN bit to determine whether an error is an NRDY interrupt, such as a receive packet error, or an overrun
error.
Responses to the tokens in the shaded boxes are executed in accordance to the buffer memory status.
(1) When IITV=0
(2) When IITV > 0
(1) IN direction:
(2) OUT direction:
O c t 1 7 , 2 0 0 8
Token
Token
SOF
The buffer flush operation is executed from the first frame after the pipe becomes valid.
The buffer flush operation is executed after the first successful transaction.
(a) If buffer is in transfer-enabled status, data is transferred as a normal response
(b) If buffer is in transfer-disabled status, zero-length packet is sent and underrun error occurs
(a) If buffer is in receive-enabled status, data is received as a normal response
(b) If buffer is in receive-disabled status, data is not received and overrun error occurs
Token received according to interval
Token received in frame outside of interval
SOF
Interval when IITV=1
S
Empty
Figure 3.22 Interval Error Occurrence Example When "IITV=1"
Token
Token
Token
Token
Token
Token
p a g e 1 5 2 o f 1 8 3
Figure 3.21 Buffer Flush Function Operation Example
S
Empty
Writing
Write end
Writing
Token
Token
Token
SOF
1
1
1
Tr ansfer -enabled
Token
Token
Token
Token
Write end
Token
Token
Token
Token
SOF
1
1
Buffer flush generated
S
Empty
Token
Token
Tran sfer- enabled status
Writing
Token
Token
Token
Token
Write end
1
1
SOF