300 Priority Encoder with Parity Checker
300 : Priority Encoder with Parity Checker
- Author: arun-goud
- Description: 9-to-4 priority encoder with parity checker and 7-seg display output
- GitHub repository
- Open in 3D viewer
- Clock: 66000000 Hz
How it works
The priority encoder with parity checker module does priority encoding of a 9-bit binary input into a 4-bit binary code and displays the decimal equivalent of that code on the 7-segment display. Additionally it also does parity checking and outputs the resultant parity bit.
It has 2 modes of operation for priority encoding and for parity checking:
For priority encoding:
- Bit towards MSB takes precedence (when
uio_in[1]is low). - Bit towards LSB takes precedence (when
uio_in[1]is high).
For parity checking:
- Parity bit is 1 when input has even number of 1s and 0 otherwise (when
uio_in[2]is low). - Parity bit is 1 when input has odd number of 1s and 0 otherwise (when
uio_in[2]is high).
The following table summarizes the modes:
uio_in[1] |
uio_in[2] |
Mode |
|---|---|---|
| 0 | X | MSB priority encode |
| 1 | X | LSB priority encode |
| X | 0 | Even parity flag |
| X | 1 | Odd parity flag |
For all the modes listed above the expected inputs and generated outputs are:
ui + uio_in[0] |
uio_out[7:4] |
uio_out[3] |
uo_out |
|---|---|---|---|
| 9-bit Binary input | 4-bit Priority code | Parity bit | 7-seg code |
The parity bit controls the DP pin of the 7-segment display.
How to test
- Set
uio_in[1]low and observe that the priority code of{uio_in[0], ui_in}with MSB having higher priority is output on the output pins (uio_out[7:4]) and on the 7-segment display connected touo_out. - Set
uio_in[1]high and observe that the priority code of{uio_in[0], ui_in}with LSB having higher priority is output on the output pins (uio_out[7:4]) and on the 7-segment display connected touo_out. - Set
uio_in[2]low and observe that the parity bituio_out[3]is getting set when the input{uio_in[0], ui_in}has even number of 1s. The DP on 7-segment display should light up when parity bit is 1. - Set
uio_in[2]high and observe that the parity bituio_out[3]is getting set when the input{uio_in[0], ui_in}has odd number of 1s. The DP on 7-segment display should light up when parity bit is 1.
IO
| # | Input | Output | Bidirectional |
|---|---|---|---|
| 0 | in_a[0] / IN0 | output[0] / SEG_A | in_b[0] / IN8 |
| 1 | in_a[1] / IN1 | output[1] / SEG_B | in_b[1] / MSB_HIGHPRMODE_n |
| 2 | in_a[2] / IN2 | output[2] / SEG_C | in_b[2] / EVENPARITY_MODE_n |
| 3 | in_a[3] / IN3 | output[3] / SEG_D | out_b[3] / PARITY_OUT |
| 4 | in_a[4] / IN4 | output[4] / SEG_E | out_b[4] / PRCODE[0] |
| 5 | in_a[5] / IN5 | output[5] / SEG_F | out_b[5] / PRCODE[1] |
| 6 | in_a[6] / IN6 | output[6] / SEG_G | out_b[6] / PRCODE[2] |
| 7 | in_a[7] / IN7 | output[7] / SEG_DP | out_b[7] / PRCODE[3] |