Datasheet

V850ES/JG3-H, V850ES/JH3-H CHAPTER 21 USB FUNCTION CONTROLLER (USBF)
R01UH0042EJ0500 Rev.5.00 Page 1078 of 1513
Aug 12, 2011
(2) UF0 EP0NAKALL register (UF0E0NA)
This register controls NAK to all the requests of Endpoint0. It is also valid for automatically executed requests.
This register can be read or written in 8-bit units.
0UF0E0NA 0
5
00
3
0
2
0
1
0 EP0NKA
Address
00200002H
After reset
00H
0467
Bit position Bit name Function
0 EP0NKA
This bit controls NAK to a transaction other than a SETUP transaction to Endpoint0
(including an automatically executed request). This bit is manipulated by FW.
1: Transmit NAK.
0: Do not transmit NAK (default value).
This register is used to prevent a conflict between a write access by FW and a read
access from SIE when the data used for an automatically executed request is to be
changed. It postpones reflecting a write access on this bit from FW while an access from
SIE is being made. Before rewriting the request data register from FW, confirm that this
bit has been correctly set to 1.
Setting this bit to 1 is reflected only in the following cases.
• Immediately after USBF has been reset and a SETUP token has never been
received
• Immediately after reception of Bus Reset and a SETUP token has never been
received
• PID of a SETUP token has been detected
• The stage has been changed to the status stage
Clearing this bit to 0 is reflected immediately, except while an IN token is being received
and a NAK response is being made.
Setting the EP0NKA bit to 1 is reflected in the above four cases during Endpoint0 transfer,
but it is reflected immediately after data has been written to the bit while Endpoint0 is
transferring no data.