Libraries GuideChapter 11: Design Elements (X74_42 to X74_521)
X74_147
10- to 4-Line Priority Encoder with Active-Low Inputs and Outputs
XC3000
| XC4000E
| XC4000X
| XC5200
| XC9000
| Spartan
| SpartanXL
| Spartan2
| Virtex
|
|---|
Macro
| Macro
| Macro
| Macro
| Macro
| Macro
| Macro
| N/A
| N/A
|
X74_147 is a 10-line-to-BCD-priority encoder that accepts data from nine active-Low inputs (I9 - I1) and produces a binary-coded decimal (BCD) representation on the four active-Low outputs A, B, C, and D. The data inputs are weighted, so when more than one input is active, only the one with the highest priority is encoded, with I9 having the highest priority. Only nine inputs are provided, because the implied “zero” condition requires no data input. “Zero” is encoded when all data inputs are High.
Inputs
| Outputs
|
|---|
I9
| I8
| I7
| I6
| I5
| I4
| I3
| I2
| I1
| D
| C
| B
| A
|
|---|
1
| 1
| 1
| 1
| 1
| 1
| 1
| 1
| 0
| 1
| 1
| 1
| 0
|
1
| 1
| 1
| 1
| 1
| 1
| 1
| 0
| X
| 1
| 1
| 0
| 1
|
1
| 1
| 1
| 1
| 1
| 1
| 0
| X
| X
| 1
| 1
| 0
| 0
|
1
| 1
| 1
| 1
| 1
| 0
| X
| X
| X
| 1
| 0
| 1
| 1
|
1
| 1
| 1
| 1
| 0
| X
| X
| X
| X
| 1
| 0
| 1
| 0
|
1
| 1
| 1
| 0
| X
| X
| X
| X
| X
| 1
| 0
| 0
| 1
|
1
| 1
| 0
| X
| X
| X
| X
| X
| X
| 1
| 0
| 0
| 0
|
1
| 0
| X
| X
| X
| X
| X
| X
| X
| 0
| 1
| 1
| 1
|
0
| X
| X
| X
| X
| X
| X
| X
| X
| 0
| 1
| 1
| 0
|
1
| 1
| 1
| 1
| 1
| 1
| 1
| 1
| 1
| 1
| 1
| 1
| 1
|
Figure 11.6 X74_147 Implementation XC3000, XC4000E, XC4000X, XC5200, XC9000, Spartan, SpartanXL