Datasheet

Universal Serial Bus Module (USB)
Technical Data MC68HC908JB8•MC68HC08JB8•MC68HC08JT8 — Rev. 2.3
160 Universal Serial Bus Module (USB) Freescale Semiconductor
9.9.1.2 Transmit Control Endpoint 0
For a control IN transaction directed at endpoint 0, the USB module will
generate an interrupt by setting the TXD0F flag in the UIR1 register. The
conditions necessary for the interrupt to occur are shown in the flowchart
in Figure 9-31.
Figure 9-31. IN Token Data Flow for Transmit Endpoint 0
VALID IN TOKEN
RECEIVED FOR ENDPOINT 0
SEND STALL
HANDSHAKE
SET TXD0F TO 1
(TXD0IE = 1)
NO INTERRUPT
SEND DATA
N
DATA PID SET BY T0SEQ
USB MODULE ENABLED?
(USBEN = 1)
TRANSMIT ENDPOINT NOT STALLED
BY FIRMWARE (ISTALL0 = 0)?
TRANSMIT ENDPOINT READY TO TRANSFER?
(TX0E = 1) AND (TXD0F = 0)
TRANSMIT ENDPOINT
INTERRUPT ENABLED?
VALID TRANSACTION
INTERRUPT GENERATED
SEND NAK
HANDSHAKE
Y
Y
Y
Y
Y
N
N
N
N
Y
NO RESPONSE
FROM USB FUNCTION
ACK RECEIVED AND NO
TIMEOUT CONDITION OCCURS?
NO RESPONSE
FROM USB FUNCTION