
147
AT85C51SND3Bx
7632A–MP3–03/06
Reset Value = 0000 0000b
Reset Value = 0000 0000b
Reset Value = 0000 0000b
Bit
Number
Bit
Mnemonic
Description
7-0 PDAT7:0
Pipe Data Bits
Set by the software to read/write a byte from/to the Pipe FIFO selected by
PNUM.
Table 151. UPBCHX Register
UPBCHX (1.D4h) – USB Pipe Data Counter High Register
7 6 5 4 3 2 1 0
- - - - - PBYCT10 PBYCT9 PBYCT8
Bit
Number
Bit
Mnemonic
Description
7-3 -
Reserved
The value read from these bits is always 0. Do not set these bits.
2-0 PBYCT10:8
Byte count (high) Bits
Set by hardware. This field is the MSB of the byte count of the FIFO endpoint.
The LSB part is provided by the UPBCLX register.
Table 152. UPBCLX Register
UPBCLX (1.D5h) – USB Pipe Data Counter Low Register
7 6 5 4 3 2 1 0
PBYCT7 PBYCT6 PBYCT5 PBYCT4 PBYCT3 PBYCT2 PBYCT1 PBYCT0
Bit
Number
Bit
Mnemonic
Description
7-0 PBYCT7:0
Byte Count (low) Bits
Set by the hardware. PBYCT10:0 is:
- (for OUT Pipe) increased after each writing into the Pipe and decremented after
each byte sent,
- (for IN Pipe) increased after each byte received by the host, and decremented
after each byte read by the software.
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