NEC switch User Manual page 133

(4) Control transfer (IN) (Transfer byte count: 9 bytes or more)
Packet from
host controller
SETUP
Setup
stage
DATA0
Data
IN
stage IN
reception
ACK
IN
IN
ACK
IN
IN
ACK
OUT
Status
DATA1
stage OUT
reception
OUT
reception
wait
Note If the ACK from the device cannot be received normally, the host transmits OUT again. Therefore, set
the OUT receive wait state for a period so that the OUT can be received. Use a normal 8-bit timer for
counting during this period.
CHAPTER 8
Packet flow
Packet from
µ
PD789800
ACK
DATA1
NAK
DATA0
NAK
DATA0/1
ACK
User's Manual U12978EJ3V0UD
USB FUNCTION
Operation of host
controller
Request
IN packet
IN packet
IN packet
ACK packet
IN packet
IN packet
ACK packet
OUT packet
USB communication
completion timer
Note
timeout
Operation of USB
µ
function of PD789800
ACK transmission
reservation
• ACK transmission
• DATA1 transmission
reservation
• DATA1 transmission
• NAK transmission
reservation
NAK transmission
reservation clear
• NAK transmission
• DATA0 transmission
reservation
• DATA0 transmission
• NAK transmission
reservation
NAK transmission
reservation clear
• NAK transmission
• DATA1 transmission
reservation
• DATA0/1 transmission
• NAK transmission
reservation
NAK transmission
reservation clear
ACK transmission
reservation
• ACK transmission
• USB communication
completion timer start
NAK transmission
reservation
133