UM10375 All information provided in this document is subject to legal disclaimers. © NXP B.V. 2011. All rights reserved.
User manual Rev. 3 — 14 June 2011 160 of 368
NXP Semiconductors
UM10375
Chapter 10: LPC13xx USB device controller
10.11.11 Select Endpoint/Clear Interrupt (Command: 0x40 - 0x47, Data: read 1
byte)
Commands 0x40 to 0x47 are identical to their Select Endpoint equivalents, with the
following differences:
• They clear the bit corresponding to the endpoint in the USBEpIntSt register.
• In case of a control OUT endpoint, they clear the STP and PO bits in the
corresponding Select Endpoint Register.
• Reading one byte is obligatory.
1 ST Stalled endpoint indicator. 0
0 The selected endpoint is not stalled.
1 The selected endpoint is stalled.
2 STP SETUP bit: the value of this bit is updated after each
successfully received packet (i.e. an ACKed package on that
particular physical endpoint).
0
0 The STP bit is cleared by doing a Select Endpoint/Clear
Interrupt on this endpoint.
1 The last received packet for the selected endpoint was a
SETUP packet.
3 PO Packet over-written bit. 0
0 The PO bit is cleared by the ‘Select Endpoint/Clear Interrupt’
command.
1 The previously received packet was over-written by a SETUP
packet.
4 EPN EP NAKed bit indicates sending of a NAK. If the host sends an
OUT packet to a filled OUT buffer, the device returns NAK. If
the host sends an IN token packet to an empty IN buffer, the
device returns NAK.
0
0 The EPN bit is reset after the device has sent an ACK after an
OUT packet or when the device has seen an ACK after sending
an IN packet.
1 The EPN bit is set when a NAK is sent and the interrupt on NAK
feature is enabled.
5 B_1_FULL The buffer 1 status. 0
0 Buffer 1 is empty.
1 Buffer 1 is full.
6 B_2_FULL The buffer 2 status. 0
0 Buffer 2 is empty.
1 Buffer 2 is full.
7 - - Reserved, user software should not write ones to reserved bits.
The value read from a reserved bit is not defined.
NA
Table 183. Select Endpoint command description
Bit Symbol Value Description Reset
value
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