PIC16C745 Datasheet, PDF (69/158 Pages) Microchip Technology – 8-Bit CMOS Microcontrollers with USB

PIC16C745/765
REGISTER 10-10: BUFFER DESCRIPTOR STATUS REGISTER. BITS WRITTEN BY THE MCU
(BDndST: 1A0h, 1A4h, 1A8h, 1ACh, 1B0h, 1B4h)
W-X
W-X
U-X
U-X
W-X
W-X
U-X
U-X
UOWN DATA0/1 —
bit7
—
DTS BSTALL —
—
bit0
R = Readable bit
W = Writable bit
U = Unimplemented bit,
read as ‘0’
-n = Value at POR reset
X = Don’t care
bit 7:
UOWN: USB Own. This UOWN bit determines who currently owns the buffer. The SIE writes a 0 to this
bit when it has completed a token. This byte of the BD should always be the last byte the MCU updates
when it initializes a BD. Once the BD has been assigned to the USB, the MCU should not change it in any
way.
1 = USB has exclusive access to the BD. The MCU should not modify the BD or buffer.
0 = The MCU has exclusive access to the BD. The USB ignores all other fields in the BD.
bit 6:
DATA0/1: This bit defines the type of data toggle packet that was transmitted or received.
1 = Data 1 packet
0 = Data 0 packet
bit 5-4: Reserved: Read as ’X’.
bit 3:
DTS: Setting this bit will enable the USB to perform Data Toggle Synchronization. If a packet arrives with
an incorrect DTS, it will be ignored and the buffer will remain unchanged.
1 = Data Toggle Synchronization is performed
0 = No Data Toggle Synchronization is performed
bit 2:
BSTALL: Buffer Stall. Setting this bit will cause the USB to issue a STALL handshake if a token is received
by the SIE that would use the BD in this location. The BD is not consumed by the SIE (the own bit remains
and the rest of the BD are unchanged) when a BSTALL bit is set.
bit 1-0: Reserved: Read as ’X’.
Note: Recommend that users not use BSF, BCF due to the dual functionality of this register.
REGISTER 10-11: BUFFER DESCRIPTOR STATUS. BITS READ BY THE MCU.
(BDndST: 1A0h, 1A4h, 1A8h, 1ACh, 1B0h, 1B4h)
R/W-0 R/W-X R/W-X R/W-X R/W-X R/W-X U-X
U-X
UOWN DATA0/1 PID3 PID2 PID1 PID0
—
bit7
—
bit0
R = Readable bit
W = Writable bit
U = Unimplemented bit,
read as ‘0’
-n = Value at POR reset
X = Don’t care
bit 7:
UOWN: USB Own. This UOWN bit determines who currently owns the buffer. The SIE writes a 0 to this
bit when it has completed a token. This byte of the BD should always be the last byte the MCU updates
when it initializes a BD. Once the BD has been assigned to the USB, the MCU should not change it in any
way.
1 = USB has exclusive access to the BD. The MCU should not modify the BD or buffer.
0 = The MCU has exclusive access to the BD. The USB ignores all other fields in the BD.
bit 6:
DATA0/1: This bit defines the type of data toggle packet that was transmitted or received.
1 = Data 1 packet
0 = Data 0 packet
bit 5-2: PID<3:0>: Packet Identifier. The received token PID value
bit 1-0: Reserved: Read as 'X'.
Note: Recommend that users not use BSF, BCF due to the dual functionality of this register.
© 1999 Microchip Technology Inc.
Advanced Information
DS41124A-page 69