Usb Descriptor Ram Address Register; Table 28-9 Usb Descriptor Ram Address Register Description - Motorola DragonBall MC9328MX1 Reference Manual

28.3.5 USB Descriptor RAM Address Register

This register allows user access to the USB descriptor RAM. The user programs a desired address into the
9-bit desired RAM address (DADR) field and follows it with a read or write to the USB_DDAT register to
complete the access. On read/write access to the USB Descriptor RAM/Endpoint Buffer Data Register
(USB_DDAT), the address in the DADR field increments automatically. When the CFG bit is set to 1, the
DADR address is ignored.
USB_DADR
BIT 31 30 29
CFG BSY
TYPE r r r
1 0 0
RESET
BIT 15 14 13
TYPE r r r
0 0 0
RESET
Table 28-9. USB Descriptor RAM Address Register Description
Name
CFG Configuration—Determines the function of USB_DDAT
Bit 31 Register. The Configuration versus Descriptor access
indicator is set automatically at power-on or hard reset
and clears after the last byte of endpoint buffer
configuration data is downloaded into the UDC.
BSY Busy—Indicates if a write is in progress to the endpoint
Bit 30 buffer. Because the front-end logic and the UDC module
operate on different clocks, the configuration download
interface busy signal is provided to ensure that writes
from the USB_DDAT register have sufficient time to
successfully enter the UDC's clock domain.
Reserved Reserved—These bits are reserved and should read 0.
Bits 29–9
DADR Desired RAM Address—Holds the desired RAM address. The user programs a desired descriptor
Bits 8–0 RAM address into the DADR field and follows it with a read or write to the USB_DDAT register to
complete the access.
MOTOROLA
USB Descriptor RAM Address Register
28 27 26 25
r r r r
0 0 0 0
12 11 10 9
r r r r
0 0 0 0
Description
USB Device Port
24 23 22 21 20
r r r r r
0 0 0 0 0
0x8000
8 7 6 5 4
DADR
rw rw rw rw rw
0 0 0 0 0
0x0000
0 = The USB_DDAT register is set to
access the descriptor storage RAM.
Configuration load has completed. The
USB_DDAT writes have no effect.
1 = The USB_DDAT register is set to
download endpoint buffer
configuration data to the UDC.
0 = No write is in progress.
1 = A write is in progress to the UDC
module's endpoint buffer. Attempt no
other operations on the USB Core
module until BSY has cleared.
Programming Model
Addr
0x00212010
19 18 17 16
r r r r
0 0 0 0
3 2 1 0
rw rw rw rw
0 0 0 0
Settings
28-13