Datasheet

Universal Serial Bus Module (USB)
Technical Data MC68HC908JB8•MC68HC08JB8•MC68HC08JT8 — Rev. 2.3
158 Universal Serial Bus Module (USB) Freescale Semiconductor
9.9.1.1 Receive Control Endpoint 0
For a control OUT transaction directed at endpoint 0, the USB module
will generate an interrupt by setting the RXD0F flag in the UIR0 register.
The conditions necessary for the interrupt to occur are shown in the
flowchart in Figure 9-29.
Figure 9-29. OUT Token Data Flow for Receive Endpoint 0
VALID OUT TOKEN
RECEIVED FOR ENDPOINT 0
ERROR FREE DATA PACKET?
NO RESPONSE
FROM USB FUNCTION
SET RXD0F TO 1
(RXD0IE = 1)
NO INTERRUPT
ACCEPT DATA
NO RESPONSE
FROM USB FUNCTION
TIMEOUT
N
SET/CLEAR R0SEQ BIT
VALID DATA TOKEN
RECEIVED FOR ENDPOINT 0?
USB MODULE ENABLED?
(USBEN = 1)
ENDPOINT 0 RECEIVE NOT STALLED?
(OSTALL0 = 0)
ENDPOINT 0 RECEIVE READY TO RECEIVE?
(RX0E = 1) AND (RXD0F = 0)
RECEIVE CONTROL ENDPOINT
INTERRUPT ENABLED?
VALID TRANSACTION
INTERRUPT GENERATED
SEND STALL
HANDSHAKE
SEND NAK
HANDSHAKE
NO RESPONSE FROM
USB FUNCTION
IGNORE TRANSACTION
Y
Y
Y
Y
Y
Y
N
N
N
N
N
Y