R01UH0823EJ0100 Rev.1.00
Page 928 of 1823
Jul 31, 2019
RX23W Group
32. USB 2.0 Host/Function Module (USBc)
shows the timing of NRDY interrupt generation when the function controller is selected.
Figure 32.10
Timing of NRDY Interrupt Generation (When Function Controller is Selected)
IN Token Packet
NAK Handshake
(1) Example of data transmission (single-buffer mode)
Ready for write access (there is no data to be transmitted)
USB bus
FIFO buffer status
NRDY interrupt
(NRDYSTS.PIPEnNRDY flag)
*2
*1
(2) Example of data reception: OUT token reception (single-buffer mode)
OUT Token Packet
Data Packet
Ready for read access (there is no space to receive data)
NAK Handshake
*1
(CRCE flag, etc.)
*3
PING Packet
NAK Handshake
(3) Example of data reception: PING token reception (single-buffer mode)
Note 1. The handshake is not used in isochronous transfers.
Note 2. The value of the PIPEnNRDY flag changes to 1 only when the PIPEnCTR.PID[1:0] bits are set to 01b (BUF response).
Note 3. The CRCE and OVRN flags change only while the target pipe is set to isochronous transfers.
Packet transmitted by host device
Packet transmitted by function device
USB bus
FIFO buffer status
NRDY interrupt
(NRDYSTS.PIPEnNRDY flag)
*2
Ready for read access (there is no space to receive data)
USB bus
FIFO buffer status
NRDY interrupt
(NRDYSTS.PIPEnNRDY flag)
*2
A NRDY interrupt is generated
A NRDY interrupt is generated
A NRDY interrupt is generated