
M66596FP/WG
rev .1.00
2006.3.14
page 92 of 127
3.9.1
Error detection with isochronous transfers
The controller has a function for detecting the error information noted below, so that when errors occur in
confirmed, and the interrupts that are generated.
(1)
PID errors
If the PID is illegal
(2)
CRC errors and bit stuffing errors
If an error occurs in the CRC of the packet being received, or the bit stuffing is illegal
(3)
Maximum packet size exceeded
The maximum packet size exceeded the set value.
(4)
Overrun and underrun errors
(a) In the Host mode
- When a buffer memory is not empty at the time of transmission of the IN direction
- When there is no transmitting data in a buffer memory at the time of transmission of the OUT
direction
(b) In the Peripheral mode
- When a buffer memory is not empty at the time of the OUT token is received.
- When there is no transmitting data in a buffer memory at the time of the IN token is received.
(5)
Interval errors
In the Peripheral mode, The following cases are interval error.
- During an isochronous IN transfer, the In token could not be received during the interval frame.
- During an isochronous OUT transfer, the OUT token is received out of the interval frame.
Table 3.24 Error detection when a token is received
Detection
priority
order
Error
Generated interrupt and status
1
PID errors
No interrupt generated (ignored)
2
CRC error and bit stuffing errors
No interrupt generated (ignored)
3
Overrun and underrun errors
NRDY interrupt, OVRN bit set
In the Host mode, the controller does
not transmit a token.
In the Peripheral mode, the controller
transmits a Zero-Length to IN token.
The controller does not receive a data
packet to an OUT token.
4
Interval errors
NRDY interrupt is generated in the
Peripheral mode.
Table 3.25 Error detection when a data packet is received
Detection
priority
order
Error
Generated interrupt and status
1
PID errors
No interrupt generated (ignored)
2
CRC error and bit stuffing errors
NRDY interrupt generated
CRCE bit set
3
Maximum packet size exceeded error
BEMP interrupt
PID set to ”STALL”