Bit
Bit
Number
Mnemonic Description
Frame Number Lower Flag
7-0
FNUM7:0
Set by hardware. These bits are the 8 LSB of the 11-bits Frame Number
information.
Reset Value = 0000 0000b
Table 118. UDMFN Register
UDMFN (1.DEh) – USB Device Frame Number Register
7
6
5
4
3
2
1
0
-
-
-
FNCERR
-
-
-
-
Bit
Bit
Number
Mnemonic Description
Reserved
7-5
4
-
The value read from these bits is always 0. Do not set these bits.
Frame Number CRC Error Flag
Set by hardware when a corrupted Frame Number in start of frame packet is
received.
This bit and the SOFI interrupt are updated at the same time.
FNCERR
-
Reserved
3-0
The value read from these bits is always 0. Do not set these bits.
Reset Value = 0000 0000b
USB Device Endpoint
Registers
Table 119. UENUM Register
UENUM (1.C9h) – USB Endpoint Number Selection Register
7
6
5
4
3
2
1
0
-
-
-
-
-
EPNUM2
EPNUM1
EPNUM0
Bit
Bit
Number
Mnemonic Description
Reserved
7-3
2-0
-
The value read from these bits is always 0. Do not set these bits.
Endpoint Number Bits
Set to select the number of the endpoint which shall be accessed by the CPU.
See Section “Endpoint Selection” for more details.
EPNUM = 111b is forbidden.
EPNUM2:0
Reset Value = 0000 0000b
Table 120. UERST Register
UERST (1.CAh) – USB Endpoint Reset Register
7
6
5
4
3
2
1
0
-
EPRST6
EPRST5
EPRST4
EPRST3
EPRST2
EPRST1
EPRST0
118
AT85C51SND3Bx
7632A–MP3–03/06
ATMEL [ ATMEL ]
