MC68HC908JG16 Datasheet, PDF (200/324 Pages) Motorola, Inc – Microcontrollers

Universal Serial Bus Module (USB)
11.9.1.1 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 11-29.
VALID OUT TOKEN
RECEIVED FOR ENDPOINT 0
Y
VALID DATA TOKEN
N
RECEIVED FOR ENDPOINT 0?
Y
USB MODULE ENABLED?
N
(USBEN = 1)
Y
ENDPOINT 0 RECEIVE NOT STALLED? N
(OSTALL0 = 0)
Y
ENDPOINT 0 RECEIVE READY TO RECEIVE? N
(RX0E = 1) AND (RXD0F = 0)
Y
ACCEPT DATA
SET/CLEAR R0SEQ BIT
N
ERROR FREE DATA PACKET?
Y
SET RXD0F TO 1
TIMEOUT
NO RESPONSE
FROM USB FUNCTION
NO RESPONSE
FROM USB FUNCTION
SEND STALL
HANDSHAKE
SEND NAK
HANDSHAKE
IGNORE TRANSACTION
NO RESPONSE FROM
USB FUNCTION
RECEIVE CONTROL ENDPOINT
N
INTERRUPT ENABLED?
(RXD0IE = 1)
Y
VALID TRANSACTION
INTERRUPT GENERATED
NO INTERRUPT
Figure 11-29. OUT Token Data Flow for Receive Endpoint 0
Technical Data
200
Universal Serial Bus Module (USB)
MC68HC908JG16 — Rev. 1.1
Freescale Semiconductor