R01UH0823EJ0100 Rev.1.00
Page 953 of 1823
Jul 31, 2019
RX23W Group
32. USB 2.0 Host/Function Module (USBc)
shows an example of interval error occurrence in the USB. There are five types of interval errors, as
shown below. The interval error is generated at the timing indicated by
in the figure, and the buffer flush function is
activated.
If an interval error occurs during an IN transfers, the buffer flush function is activated; if it occurs during an OUT
transfer, an NRDY interrupt is generated.
The FRMNUM.OVRN flag should be used to distinguish between NRDY interrupts such as received packet errors and
overrun errors.
In response to tokens that are shaded in the figure, responses are sent according to the buffer memory status.
IN direction
If the buffer is in the transmission enabled state, the data is transferred as a normal response.
If the buffer is in the transmission disabled state, a zero-length packet is sent and an underrun error occurs.
OUT direction
If the buffer is in the reception enabled state, the data is received as a normal response.
If the buffer is in the reception disabled state, the data is discarded and an overrun error occurs.
Figure 32.20
Example of Interval Error Occurrence When IITV[2:0] = 001b
1
Token
(1) Normal transfer
1
1
1
1
1
1
1
SOF
Token received in the specified interval
Token received in the frame outside the interval
Interval when IITV = 1
(2) Token corrupted
(3) Packet inserted
(4) Frame misaligned 1
(5) Frame misaligned 2
(6) Token delayed
Token
Token
Token
Token
Token
Token
Token
Token
Token
Token
Token
Token
Token
Token
Token
Token
Token
Token
Token
Token
Token
Token
Token
Token