EP1C3 ALTERA [Altera Corporation], EP1C3 Datasheet - Page 28

• Manufacturer Part Number: EP1C3
• Description: Cyclone FPGA Family
• Manufacturer: ALTERA [Altera Corporation]

Cyclone FPGA Family Data Sheet
28
Byte Enables
M4K blocks support byte writes when the write port has a data width of
16, 18, 32, or 36 bits. The byte enables allow the input data to be masked
so the device can write to specific bytes. The unwritten bytes retain the
previous written value.
Notes to
(1)
(2)
Control Signals & M4K Interface
The M4K blocks allow for different clocks on their inputs and outputs.
Either of the two clocks feeding the block can clock M4K block registers
(renwe, address, byte enable, datain, and output registers). Only the
output register can be bypassed. The six labclk signals or local
interconnects can drive the control signals for the A and B ports of the
M4K block. LEs can also control the clock_a, clock_b, renwe_a,
renwe_b, clr_a, clr_b, clocken_a, and clocken_b signals, as
shown in
The R4, C4, and direct link interconnects from adjacent LABs drive the
M4K block local interconnect. The M4K blocks can communicate with
LABs on either the left or right side through these row resources or with
LAB columns on either the right or left with the column resources. Up to
10 direct link input connections to the M4K block are possible from the left
adjacent LABs and another 10 possible from the right adjacent LAB. M4K
block outputs can also connect to left and right LABs through 10 direct
link interconnects each.
interface.
Table 8. Byte Enable for M4K Blocks
Any combination of byte enables is possible.
Byte enables can be used in the same manner with 8-bit words, i.e., in 16 and 32
modes.
byteena[3..0]
Table
[0] = 1
[1] = 1
[2] = 1
[3] = 1
Figure
8:
15.
Table 8
Figure 16
datain 18
summarizes the byte selection.
[17..9]
shows the M4K block to logic array
[8..0]
–
–
Notes
(1),
(2)
Preliminary Information
Altera Corporation
datain 36
[26..18]
[35..27]
[17..9]
[8..0]