258
8331B–AVR–03/12
Atmel AVR XMEGA AU
• Bit 7:0 – CNT[7:0]: Endpoint Byte Counter
This byte contains the eight lsbs of the USB endpoint counter (CNT).
20.14.4
CNTH – Counter High
• Bit 6 – AZLP: Automatic Zero Length Packet
When this bit is set, the USB module will manage the ZLP handshake by hardware. This
applies to IN endpoints only. When this bit is zero, the ZLP handshake must be managed by
firmware.
• Bit 6:2 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always
write these bits to zero when this register is written.
• Bit 1:0 – CNT[9:8]: Endpoint Byte Counter
These bits contain the two msbs of the USB endpoint counter (CNT).
20.14.5
DATAPTRL – Data Pointer Low
The DATAPTRL and DATAPTRH registers represent the 16-bit value, DATAPTR, that contains
the SRAM address to the endpoint data buffer.
• Bit 7:0 – DATAPTR[7:0]: Endpoint Dta Pointer Low
This byte contains the eight lsbs of the endpoint data pointer (DATAPTR).
20.14.6
DATAPTRH – Data Pointer High
Bit
7
6
5
4
3
2
1
0
CNT[7:0]
CNTL
Read/Write
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Initial Value
X
X
X
X
X
X
X
X
Bit
7
6
5
4
3
2
1
0
AZLP
–
–
–
–
–
CNT[9:8]
CNTH
Read/Write
R/W
R
R
R
R
R
R/W
R/W
Initial Value
X
X
X
X
X
X
X
X
Bit
7
6
5
4
3
2
1
0
DATAPTR[7:0]
DATAPTRL
Read/Write
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Initial Value
X
X
X
X
X
X
X
X
Bit
7
6
5
4
3
2
1
0
DATAPTR[15:8]
DATAPTRH
Read/Write
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Initial Value
X
X
X
X
X
X
X
X
