Manual

139
AT89C5131
4136A–USB–03/03
Table 90. UEPDATX Register
UEPDATX (S:CFh)
USB FIFO Data Endpoint X (X = EPNUM set in UEPNUM Register UEPNUM (S:C7h)
USB Endpoint Number)
Reset Value = XXh
Table 91. UBYCTLX Register
UBYCTLX (S:E2h)
USB Byte Count Low Register X (X = EPNUM set in UEPNUM Register UEPNUM
(S:C7h) USB Endpoint Number)
Reset Value = 00h
76543210
FDAT7 FDAT6 FDAT5 FDAT4 FDAT3 FDAT2 FDAT1 FDAT0
Bit Number
Bit
Mnemonic Description
7 - 0
FDAT[7:0]
Endpoint X FIFO data
Data byte to be written to FIFO or data byte to be read from the FIFO, for the
Endpoint X (see EPNUM).
76543210
BYCT7 BYCT6 BYCT5 BYCT4 BYCT3 BYCT2 BYCT1 BYCT0
Bit Number
Bit
Mnemonic Description
7 - 0 BYCT[7:0]
Byte Count LSB
Least Significant Byte of the byte count of a received data packet. The most
significant part is provided by the UBYCTHX Register UBYCTHX (S:E3h) USB
Byte Count High Register X (X = EPNUM set in UEPNUM Register UEPNUM
(S:C7h) USB Endpoint Number) (see Figure 91 on page 139). This byte count is
equal to the number of data bytes received after the Data PID.