CR04
CR04 can only be accessed in the configuration state and after the CSR has been initialized to 04H. The default
value after power up is 00H (Table 80).
Table 80 - CR04: Parallel and Serial Extended Setup Register
BIT
NO.
BIT NAME
DESCRIPTION
1,0
Bit 1
0
Bit 0
0
If CR1 bit 3 is a low level then:
Parallel
Port
Extended
Modes
Standard and Bi-directional Modes (SPP) (default)
0
1
1
1
0
1
EPP Mode and SPP
ECP Mode2
ECP Mode & EPP Mode1,2
2,3
Parallel
Refer to Parallel Port Floppy Disk Controller description.
Port FDC
Bit 3
Bit 2
0
0
1
1
0
1
0
1
Normal
PPFD1
PPFD2
Reserved
4
5
MIDI 13
MIDI 23
Serial Clock Select Port 1: A low level on this bit, disables MIDI support, clock =
divide by 13 (default). A high level on this bit enables MIDI support, clock = divide
by 12.
Serial Clock Select Port 2: A low level on this bit, disables MIDI support, clock =
divide by 13 (default). A high level on this bit enables MIDI support, clock = divide
by 12.
6
7
EPP Type
Reserved4
0 = EPP 1.9 (default)
1 = EPP 1.7
Reserved - Read as 0.
Note1: In this mode, EPP can be selected through the ecr register of ECP as mode 100.
Note2: In these modes, 2 drives can be supported directly, 3 or 4 drives must use external 4 drive support.
SPP can be selected through the ecr register of ECP as mode 000.
Note3: MIDI Support: The Musical Instrumental Digital Interface (MIDI) operates at
31.25Kbaud (+/-1%) which can be derived from 125KHz. (24 MHz/12=2 MHz, 2
MHz/16=125 KHz).
Note4: The function of this bit has been modified from the FDC37C669. This bit’s former
function, the selection of the pins for IR receive and transmit, has been moved to
CR0A.
SMSC DS – FDC37N769
Page 100 of 137
Rev. 02-16-07
DATASHEET
SMSC [ SMSC CORPORATION ]
