Intel SA-1100 11.8.4 UDC Address Register, 11.8.5 UDC OUT Max Packet Register

11-66 SA-1100 Developer’s Manual
Peripheral Control Module
11.8.4 UDC Address Register
The UDC address register contains a 7-bit field that holds the device address. After a reset of the
UDC core, the value of this register is zero. The CPU writes an address to this register when it
receives a SET_ADDRESS from the USB host controller. It extracts the address assigned to the
UDC from the SET_ADDRESS command and writes the value into the UDC address register. The
new address is not propagated to the rest of the UDC core until the SET_ADDRESS command is
completed with an acknowledged handshake from the UDC.
11.8.5 UDC OUT Max Packet Register
The UDC OUT max packet register holds the value of the maximum packet size the UDC core will
accept minus one. This is done in order to accommodate maximum packets of 256 bytes, without
going to a max packet field of more than 8 bits. In order to accept packets up to 256 bytes, a value
of 0xff (255) should be written into the OUT max packet register. At reset the OUT max packet
register contains 0x08, and will therefore accept packets of length 9 bits or less.
Address: 0h 8000 0004 UDCAR Read/Write
Bit76543210
Res 7-bit Function Address
Reset00000000
Bit Name Description
7—Reserved.
Always read zero.
6..0 Address Function address field
7-bit function address. Reset to all zero.
Address: 0h 8000 0008 UDCOMP Read/Write
Bit76543210
Max Packet Size - 1
Reset00001000
Bit Name Description
7..0 OUT
MaxP OUT max packet size.
8-bit field containing the value of the maximum packet size minus one.