lf4415 LOGIC Devices Inc., lf4415 Datasheet - Page 20

• Manufacturer Part Number: lf4415
• Description: Video Memory / Fifo
• Manufacturer: LOGIC Devices Inc.

Register B
Register C
Depth
Expansion:
Chip Position
Depth
Expansion:
# of Devices
Register D, E, F
Programamble
Empty Flag 0
Definition
LOGIC Devices Incorporated
Configuration Register Definitions
Register C [7:4] = BASE_ADDR[3:0] - position of chip in depth expansion; BASE_ADDR[3:0]
must not exceed NUM_DEV[3:0]
0000:
0001:
......
Register C [3:0] = NUM_CASC_DEV[3:0] - number of devices tied together* for
a concatenated address space. (ignore unless performing Depth Expansion)
0000:
0001:
...
1100:
*Note limits on number of possible device connections (related to WIDTH control):
8bit data: 4 or less LF4430s (W = 00)
10bit data: 5 or less LF4430s (W = 01)
12bit data: 6 or less LF4430s (W = 1x)
Register D [7:6] Reserved [LOAD ‘00’ IF MODIFYING REG D]
Registers D, E, F = EMPTY_THRESH_0[21:0] - PE0 Programmable threshold for the Partially
Empty Flag behavior
EmptyThresh0 is a 22bit constant used to define the emptiness threshold for the PE0 flag. The default
is 1/80th of the total memory space in single channel mode. See Excel file on logicdevices.com
Application Notes area for setting this threshold. In single channel and cascade modes, the
EmptyThresh0 applies. In dual channel mode, this threshold only applies to channel 0’s PE flag.
Register D= EMPTY_THRESH_0 [21:16] (DEFAULT= 00000)
5:0=EMPTY_THRESH_0 [21:16] Most significant 6 bits of the 22bit EmptyThresh0
Register E = EMPTY_THRESH_0 [15:8] (DEFAULT= 00000000)
7:0=EMPTY_THRESH_0 [15:8] Middle byte of the 22bit EmptyThresh0
Register F = EMPTY_THRESH_0 [7:0] (DEFAULT= 00000000)
7:0=EMPTY_THRESH_0 [7:0]
www.logicdevices.com
Register B [7:0] = Reserved
12x depth - twelve devices; sequential R/W addresses, modulo 23,284,800 (8bit mode)
2x depth - two devices; sequential R/W addresses, modulo 7,761,600 (8bit mode)
single device (DEFAULT) - no depth expansion
device n of N
device 2 of N
single-chip operation OR device 1 of N (DEFAULT)
Least significant byte of the 22bit EmptyThresh0
20
PRELIMINARY
High Performance Memory Product
Video Memory / FIFO
MEMORY
FRAME
January 23, 2008 LDS-44xx-A
...
LF4460
LF4430
LF4415