ST72F63 STMICROELECTRONICS [STMicroelectronics], ST72F63 Datasheet - Page 72

• Manufacturer Part Number: ST72F63
• Manufacturer: STMICROELECTRONICS [STMicroelectronics]

ST7263B
USB INTERFACE (Cont’d)
ENDPOINT n REGISTER B (EPnRB)
Read / Write
Reset Value: 0000 xxxx (0xh)
These registers (EP1RB and EP2RB) are used for
controlling data reception on Endpoints 1 and 2.
They are also reset by the USB bus reset.
Note: Endpoint 2 and the EP2RB register are not
available on some devices (see device feature list
and register map).
Bit 7 = CTRL Control.
This bit should be 0.
Note: If this bit is 1, the Endpoint is a control end-
point. (Endpoint 0 is always a control Endpoint, but
it is possible to have more than one control End-
point).
Bit 6 = DTOG_RX Data toggle, for reception trans-
fers .
It contains the expected value of the toggle bit
(0=DATA0, 1=DATA1) for the next data packet.
This bit is cleared by hardware in the first stage
(Setup Stage) of a control transfer (SETUP trans-
actions start always with DATA0 PID). The receiv-
er toggles DTOG_RX only if it receives a correct
data packet and the packet’s data PID matches
the receiver sequence bit.
Bits 5:4 = STAT_RX [1:0] Status bits, for reception
transfers.
These bits contain the information about the end-
point status, which are listed below:
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STAT_RX1
0
0
CTRL
7
DTOG
_RX
STAT_RX0 Meaning
0
1
STAT
_RX1
STAT
_RX0
DISABLED: reception
transfers cannot be exe-
cuted.
STALL: the endpoint is
stalled and all reception
requests
STALL handshake.
EA3
EA2
result
EA1
in
EA0
0
a
These bits are written by software. Hardware sets
the STAT_RX bits to NAK when a correct transfer
has occurred (CTR=1) related to an OUT or SET-
UP transaction addressed to this endpoint, so the
software has the time to elaborate the received
data before acknowledging a new transaction.
Bits 3:0 = EA[3:0] Endpoint address .
Software must write in this field the 4-bit address
used to identify the transactions directed to this
endpoint. Usually EP1RB contains “0001” and
EP2RB contains “0010”.
ENDPOINT 0 REGISTER B (EP0RB)
Read / Write
Reset Value: 1000 0000 (80h)
This register is used for controlling data reception
on Endpoint 0. It is also reset by the USB bus re-
set.
Bit 7 = Forced by hardware to 1.
Bits 6:4 = Refer to the EPnRB register for a de-
scription of these bits.
Bits 3:0 = Forced by hardware to 0.
STAT_RX1
1
1
7
1
DTOG
RX
STAT_RX0 Meaning
0
1
STAT
RX1
STAT
RX0
NAK: the endpoint is na-
ked and all reception re-
quests result in a NAK
handshake.
VALID: this endpoint is
enabled for reception.
0
0
0
0
0