99 Test Design 1
99 : Test Design 1
- Author: Evan Armoogan
- Description: Test design, not sure what it does yet
- GitHub repository
- Clock: 0 Hz
How it works
This project implements a synchronous 4 bit counter. There are 3 control signals described below.
- Cp: Indicates that the counter value should be incremented on the current clock cycle
- Ep: Outputs the enable signal on the uo_out wire
- Lp: Indicates that the value on the bus should be loaded into the counter.
The counter will enumerate all values between 0 and F (15) before looping back to 0 and starting again. The counter will clear back to 0 whenever the chip is reset.
| Signal | TinyTapeout I/O |
|---|---|
| Cp | ui_in[1] |
| Ep | ui_in[2] |
| Lp | ui_in[0] |
| Load Input | ui_in[7:4] |
| Counter Output | uo_out[3:0] |
Note: All control signals (Cp, Ep, and Lp) are active high.
How to test
Connect any probe that allows you to read 4 bits from the hardware to uo_out. Now generate a sequence of operations that tests all of the following operations:
- Enable the output by asserting Ep
- Start counting by asserting Cp
- Pause counting by deasserting Cp
- Disable the output by deasserting Ep. Should see high impedence on the output wire
- Load a new value into the counter while paused
- Load a new value while the counter is incrementing
- Reset the chip and verify the counter is reset to 0
Some example test waveforms are attached:
- test_count: Counts from 0 up to F
- test_load: Counts and loads the value of 5 after 9 clock periods
- test_pause: Counts and pauses for 2 clock periods after 7 clock periods
- test_pause_load: Counts and pauses after 7 clock periods then loads
- test_disable: Disables counter output for 2 cycles after 9 clock periods
- test_loop: Counts from 0 up to F then loops back to 0
External hardware
No external hardware is required to run the counter. It may be helpful to have tools that allow you to easily view the output of the counter.
IO
| # | Input | Output | Bidirectional |
|---|---|---|---|
| 0 | in_0 | out_0 | bidir_0 |
| 1 | in_1 | out_1 | bidir_1 |
| 2 | in_2 | out_2 | bidir_2 |
| 3 | in_3 | out_3 | bidir_3 |
| 4 | in_4 | out_4 | bidir_4 |
| 5 | in_5 | out_5 | bidir_5 |
| 6 | in_6 | out_6 | bidir_6 |
| 7 | in_7 | out_7 | bidir_7 |