Datasheet

145
4337K–USB–04/08
AT89C5130A/31A-M
Table 21-10. 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 21-11. UBYCTLX Register
UBYCTLX (S:E2h)
USB Byte Count Low Register X (X = EPNUM set in UEPNUM Register UEP-
NUM (S:C7h) USB Endpoint Number)
Reset Value = 00h
7 6 5 4 3 2 1 0
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).
7 6 5 4 3 2 1 0
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 21-11 on page 145). This byte count is equal to the number of data
bytes received after the Data PID.