PIC18F2450/4450
transactions. For Endpoint 0, this bit should always be
cleared since the USB specifications identify
Endpoint 0 as the default control endpoint.
14.2.4
USB ENDPOINT CONTROL
Each of the 16 possible bidirectional endpoints has its
own independent control register, UEPn (where ‘n’ rep-
resents the endpoint number). Each register has an
identical complement of control bits. The prototype is
shown in Register 14-4.
The EPOUTEN bit (UEPn<2>) is used to enable or dis-
able USB OUT transactions from the host. Setting this
bit enables OUT transactions. Similarly, the EPINEN bit
(UEPn<1>) enables or disables USB IN transactions
from the host.
The EPHSHK bit (UEPn<4>) controls handshaking for
the endpoint; setting this bit enables USB handshaking.
Typically, this bit is always set except when using
isochronous endpoints.
The EPSTALL bit (UEPn<0>) is used to indicate a
STALL condition for the endpoint. If a STALL is issued
on a particular endpoint, the EPSTALL bit for that end-
point pair will be set by the SIE. This bit remains set
until it is cleared through firmware, or until the SIE is
reset.
The EPCONDIS bit (UEPn<3>) is used to enable or
disable USB control operations (SETUP) through the
endpoint. Clearing this bit enables SETUP
transactions. Note that the corresponding EPINEN and
EPOUTEN bits must be set to enable IN and OUT
REGISTER 14-4: UEPn: USB ENDPOINT n CONTROL REGISTER (UEP0 THROUGH UEP15)
U-0
—
U-0
—
U-0
—
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
EPSTALL(1)
bit 0
EPHSHK EPCONDIS
EPOUTEN
EPINEN
bit 7
Legend:
R = Readable bit
-n = Value at POR
W = Writable bit
‘1’ = Bit is set
U = Unimplemented bit, read as ‘0’
‘0’ = Bit is cleared x = Bit is unknown
bit 7-5
bit 4
Unimplemented: Read as ‘0’
EPHSHK: Endpoint Handshake Enable bit
1= Endpoint handshake enabled
0= Endpoint handshake disabled (typically used for isochronous endpoints)
bit 3
EPCONDIS: Bidirectional Endpoint Control bit
If EPOUTEN = 1and EPINEN = 1:
1= Disable Endpoint n from control transfers; only IN and OUT transfers allowed
0= Enable Endpoint n for control (SETUP) transfers; IN and OUT transfers also allowed
bit 2
bit 1
bit 0
EPOUTEN: Endpoint Output Enable bit
1= Endpoint n output enabled
0= Endpoint n output disabled
EPINEN: Endpoint Input Enable bit
1= Endpoint n input enabled
0= Endpoint n input disabled
EPSTALL: Endpoint Stall Enable bit(1)
1= Endpoint n is stalled
0= Endpoint n is not stalled
Note 1: Valid only if Endpoint n is enabled; otherwise, the bit is ignored.
© 2006 Microchip Technology Inc.
Advance Information
DS39760A-page 135
MICROCHIP [ MICROCHIP ]
