r4f2456 Renesas Electronics Corporation., r4f2456 Datasheet - Page 996

• Manufacturer Part Number: r4f2456
• Description: 16-bit Single-chip Microcomputer H8s Family / H8s/2400 Series
• Manufacturer: Renesas Electronics Corporation.

Section 16 USB Function Module (USB)
16.5.6
•
EP1 has two 64-byte FIFOs, but the user can receive data and read receive data without being
aware of this dual-FIFO configuration.
When one FIFO is full after reception is completed, the EP1 FULL bit in IFR2 is set. After the
first receive operation into one of the FIFOs when both FIFOs are empty, the other FIFO is empty,
and so the next packet can be received immediately. When both FIFOs are full, NAK is returned
to the host automatically. When reading of the receive data is completed following data reception,
1 is written to the EP1 RDFN bit in TRG1. This operation empties the FIFO that has just been
read, and makes it ready to receive the next packet.
Rev. 1.00 Sep. 19, 2008 Page 966 of 1342
REJ09B0467-0100
Dual FIFOs (EP1)
EP1 Bulk-Out Transfer
Clear EP1 FIFO full status.
(IFR2.EP1 FULL = 0)
Data reception from host
Set EP1 FIFO full status.
(IFR2.EP1 FULL = 1)
OUT token reception
in EP1 FIFO?
USB function
Figure 16.16 EP1 Bulk-Out Transfer Operation
Space
Yes
Yes
ACK
NAK
No
No
Interrupt
request
Interrupt request
Read EP1 receive data
size register (EPSZ1).
Write 1 to EP1 read
complete bit.
(TRG1.EP1 RDFN = 1)
Read data from EP1
data register (EPDR1).
Application