PIC18F4550-IP Datasheet, PDF (174/438 Pages) Microchip Technology – 28/40/44-Pin, High-Performance, Enhanced Flash, USB Microcontrollers with nanoWatt Technology

PIC18F2455/2550/4455/4550
17.2.4 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 17-4.
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 EPCONDIS bit (UEPn<3>) is used to enable or
disable USB control operations (SETUP) through the
endpoint. Clearing this bit enables SETUP transac-
tions. Note that the corresponding EPINEN and
EPOUTEN bits must be set to enable IN and OUT
transactions. For Endpoint 0, this bit should always be
cleared since the USB specifications identify
Endpoint 0 as the default control endpoint.
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 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.
REGISTER 17-4: UEPn: USB ENDPOINT n CONTROL REGISTER (UEP0 THROUGH UEP15)
U-0
—
bit 7
U-0
U-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
—
—
EPHSHK EPCONDIS EPOUTEN EPINEN EPSTALL
bit 0
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
bit 3
bit 2
bit 1
bit 0
Unimplemented: Read as ‘0’
EPHSHK: Endpoint Handshake Enable bit
1 = Endpoint handshake enabled
0 = Endpoint handshake disabled (typically used for isochronous endpoints)
EPCONDIS: Bidirectional Endpoint Control bit
If EPOUTEN = 1 and 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
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 Indicator bit
1 = Endpoint n has issued one or more STALL packets
0 = Endpoint n has not issued any STALL packets
DS39632E-page 172
© 2009 Microchip Technology Inc.