Datasheet

V850ES/JG3-H, V850ES/JH3-H CHAPTER 21 USB FUNCTION CONTROLLER (USBF)
R01UH0042EJ0500 Rev.5.00 Page 1162 of 1513
Aug 12, 2011
(12) UF0 descriptor length register (UF0DSCL)
This register stores the length of the value that is to be returned in response to the GET_DESCRIPTOR
Configuration request. The value of this register is the number of bytes of all the descriptors set by the UF0CIEn
register minus 1 (n = 0 to 255). The total descriptor length that is to be returned in response to the
GET_DESCRIPTOR Configuration request is determined according to the value of this register.
This register can be read or written in 8-bit units. However, data can be written to this register only when the
EP0NKA bit is set to 1.
Processing of wLength is automatically controlled. If this register is set to 00H, it means that the descriptor to be
returned is 1 byte long. If the register is set to FFH, a descriptor length of 256 bytes is returned. When a
descriptor exceeding 256 bytes in length is used, set the CDCGDST bit of the UF0MODC register to 1 and
process the GET_DESCRIPTOR request by FW (at this time, the CDCGD bit of the UF0MODS register is also set
to 1).
Caution To rewrite this register, set the EP0NKA bit to 1 before reading the register contents, and rewrite
the register contents after confirming that the bit has been set, in order to prevent conflict
between a read access and a write access.
DPL7UF0DSCL DPL6
5
DPL5 DPL4
3
DPL3
2
DPL2
1
DPL1 DPL0
Address
002001A0H
After reset
00H
0467
Bit position Bit name Function
7 to 0 DPL7 to DPL0
These bits set the value of the number of bytes of all the descriptors to be returned in
response to the GET_DESCRIPTOR Configuration request minus 1.