MC908JB16DWE Datasheet, PDF (204/332 Pages) Freescale Semiconductor, Inc – Microcontrollers

Universal Serial Bus Module (USB)
11.9.1.2 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 11-31.
VALID IN TOKEN
RECEIVED FOR ENDPOINT 0
Y
USB MODULE ENABLED?
N
(USBEN = 1)
Y
TRANSMIT ENDPOINT NOT STALLED N
BY FIRMWARE (ISTALL0 = 0)?
Y
TRANSMIT ENDPOINT READY TO TRANSFER? N
(TX0E = 1) AND (TXD0F = 0)
Y
SEND DATA
DATA PID SET BY T0SEQ
ACK RECEIVED AND NO
N
TIMEOUT CONDITION OCCURS?
Y
SET TXD0F TO 1
NO RESPONSE
FROM USB FUNCTION
SEND STALL
HANDSHAKE
SEND NAK
HANDSHAKE
NO RESPONSE
FROM USB FUNCTION
TRANSMIT ENDPOINT
INTERRUPT ENABLED?
N
(TXD0IE = 1)
Y
VALID TRANSACTION
INTERRUPT GENERATED
NO INTERRUPT
Figure 11-31. IN Token Data Flow for Transmit Endpoint 0
Technical Data
204
Universal Serial Bus Module (USB)
MC68HC908JB16 — Rev. 1.1
Freescale Semiconductor