UM10462
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User manual
Rev. 5.5 — 21 December 2016
235 of 523
NXP Semiconductors
UM10462
Chapter 11: LPC11U3x/2x/1x USB2.0 device controller
Table 227. Endpoint commands
Symbol
Access
Description
A
RW
Active
The buffer is enabled. HW can use the buffer to store received OUT data or
to transmit data on the IN endpoint.
Software can only set this bit to ‘1’. As long as this bit is set to one,
software is not allowed to update any of the values in this 32-bit word. In
case software wants to deactivate the buffer, it must write a one to the
corresponding “skip” bit in the USB Endpoint skip register. Hardware can
only write this bit to zero. It will do this when it receives a short packet or
when the NBytes field transitions to zero or when software has written a
one to the “skip” bit.
D
RW
Disabled
0: The selected endpoint is enabled.
1: The selected endpoint is disabled.
If a USB token is received for an endpoint that has the disabled bit set,
hardware will ignore the token and not return any data or handshake.
When a bus reset is received, software must set the disable bit of all
endpoints to 1.
Software can only modify this bit when the active bit is zero.
S
RW
Stall
0: The selected endpoint is not stalled
1: The selected endpoint is stalled
The Active bit has always higher priority than the Stall bit. This means that
a Stall handshake is only sent when the active bit is zero and the stall bit is
one.
Software can only modify this bit when the active bit is zero.
TR
RW
Toggle Reset
When software sets this bit to one, the HW will set the toggle value equal to
the value indicated in the “toggle value” (TV) bit.
For the control endpoint zero, this is not needed to be used because the
hardware resets the endpoint toggle to one for both directions when a
setup token is received.
For the other endpoints, the toggle can only be reset to zero when the
endpoint is reset.
RF / TV
RW
Rate Feedback mode / Toggle value
For bulk endpoints and isochronous endpoints this bit is reserved and must
be set to zero.
For the control endpoint zero this bit is used as the toggle value. When the
toggle reset bit is set, the data toggle is updated with the value
programmed in this bit.
When the endpoint is used as an interrupt endpoint, it can be set to the
following values.
0: Interrupt endpoint in ‘toggle mode’
1: Interrupt endpoint in ‘rate feedback mode’. This means that the data
toggle is fixed to zero for all data packets.
When the interrupt endpoint is in ‘rate feedback mode’, the TR bit must
always be set to zero.