973 freqSweep
973 : freqSweep
- Author: Jesus Minguillon
- Description: Frequency sweeper
- GitHub repository
- Clock: 5000000 Hz
How it works
The project (src/project.v) implements a clock frequency sweeper in Verilog. It uses the Tiny Tapeout clock as input to generate a clock signal at the output uo[0] whose frequency is divided by 2 every 15 clock cycles. It goes from 1/2 to 1/16 of the input clock frequency and starts again. Input ui[0] is used as internal enable (active high).
How to test
For simulation, use the test bench (test/tb.v), which includes a module (src/periodCount.v) for measuring the frequency (or period) ratio between input and output clocks. Use the Python script (test/test.py) if you want to perform unit tests using cocotb. For hardware testing, make sure the internal enable (input ui[0]) is high and check the output clock at output uo[0] using an oscilloscope.
Gate level simulation (5 MHz input clock)
The frequency (or period) ratio between the input clock (clk) and the output clock (uo_out[0]) is given by clk_factor register of periodCount module:
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Unit tests:
(venv) jesus@ws131571:~/tt09-verilog-freqSweep/test$ make -B GATES=yes
rm -f results.xml
"make" -f Makefile results.xml
make[1]: Entering directory '/home/jesus/tt09-verilog-freqSweep/test'
mkdir -p sim_build/gl
/usr/bin/iverilog -o sim_build/gl/sim.vvp -D COCOTB_SIM=1 -s tb -g2012 -DGL_TEST -DFUNCTIONAL -DUSE_POWER_PINS -DSIM -DUNIT_DELAY=#1 -f sim_build/gl/cmds.f /home/jesus/ttsetup/pdk/sky130A/libs.ref/sky130_fd_sc_hd/verilog/primitives.v /home/jesus/ttsetup/pdk/sky130A/libs.ref/sky130_fd_sc_hd/verilog/sky130_fd_sc_hd.v /home/jesus/tt09-verilog-freqSweep/test/gate_level_netlist.v /home/jesus/tt09-verilog-freqSweep/test/periodCount.v /home/jesus/tt09-verilog-freqSweep/test/tb.v
rm -f results.xml
MODULE=test TESTCASE= TOPLEVEL=tb TOPLEVEL_LANG=verilog \
/usr/bin/vvp -M /home/jesus/ttsetup/venv/lib/python3.12/site-packages/cocotb/libs -m libcocotbvpi_icarus sim_build/gl/sim.vvp
-.--ns INFO gpi ..mbed/gpi_embed.cpp:108 in set_program_name_in_venv Using Python virtual environment interpreter at /home/jesus/ttsetup/venv/bin/python
-.--ns INFO gpi ../gpi/GpiCommon.cpp:101 in gpi_print_registered_impl VPI registered
0.00ns INFO cocotb Running on Icarus Verilog version 12.0 (stable)
0.00ns INFO cocotb Running tests with cocotb v1.9.1 from /home/jesus/ttsetup/venv/lib/python3.12/site-packages/cocotb
0.00ns INFO cocotb Seeding Python random module with 1729775152
0.00ns INFO cocotb.regression Found test test.test_startup
0.00ns INFO cocotb.regression Found test test.test_reset
0.00ns INFO cocotb.regression Found test test.test_internal_enable
0.00ns INFO cocotb.regression Found test test.test_period_count
0.00ns INFO cocotb.regression running test_startup (1/4)
0.00ns INFO cocotb.tb Startup test with reset and internal enable
0.00ns INFO cocotb.tb rst_n = 0, ui_in[0] = 0
VCD info: dumpfile tb.vcd opened for output.
2.00ns INFO cocotb.tb uo_out[0] = 0
2000.00ns INFO cocotb.tb rst_n = 1, ui_in[0] = 0
2202.00ns INFO cocotb.tb uo_out[0] = 0
4000.00ns INFO cocotb.tb rst_n = 1, ui_in[0] = 1
4202.00ns INFO cocotb.tb uo_out[0] = 1
4402.00ns INFO cocotb.tb uo_out[0] = 0
4402.00ns INFO cocotb.tb Wait until 6 us
6000.00ns INFO cocotb.tb End of startup test
6000.00ns INFO cocotb.regression test_startup passed
6000.00ns INFO cocotb.regression running test_reset (2/4)
6000.00ns INFO cocotb.tb Reset test
6000.00ns INFO cocotb.tb rst_n = 0, ui_in[0] = 1
6002.00ns INFO cocotb.tb uo_out[0] = 0
6002.00ns INFO cocotb.tb clk_factor = 1
6202.00ns INFO cocotb.tb uo_out[0] = 0
6202.00ns INFO cocotb.tb clk_factor = 1
8000.00ns INFO cocotb.tb uo_out[0] = 0
8000.00ns INFO cocotb.tb clk_factor = 1
8000.00ns INFO cocotb.tb rst_n = 1, ui_in[0] = 1
8202.00ns INFO cocotb.tb uo_out[0] = 1
8202.00ns INFO cocotb.tb clk_factor = 1
8402.00ns INFO cocotb.tb uo_out[0] = 0
8402.00ns INFO cocotb.tb clk_factor = 1
8402.00ns INFO cocotb.tb Wait until 10 us
10000.00ns INFO cocotb.tb End of reset test
10000.00ns INFO cocotb.regression test_reset passed
10000.00ns INFO cocotb.regression running test_internal_enable (3/4)
10000.00ns INFO cocotb.tb Internal enable test
10000.00ns INFO cocotb.tb rst_n = 1, ui_in[0] = 0
11600.00ns INFO cocotb.tb rst_n = 1, ui_in[0] = 1
11802.00ns INFO cocotb.tb uo_out[0] = 1
11802.00ns INFO cocotb.tb clk_factor = 2
11802.00ns INFO cocotb.tb Wait until 13 us
13000.00ns INFO cocotb.tb Reset for 800 ns and wait 200 ns
14000.00ns INFO cocotb.tb End of internal enable test
14000.00ns INFO cocotb.regression test_internal_enable passed
14000.00ns INFO cocotb.regression running test_period_count (4/4)
14000.00ns INFO cocotb.tb Period count test
14402.00ns INFO cocotb.tb clk_factor = 2
20802.00ns INFO cocotb.tb clk_factor = 4
33602.00ns INFO cocotb.tb clk_factor = 8
59202.00ns INFO cocotb.tb clk_factor = 16
59202.00ns INFO cocotb.tb Wait until 200 us
200000.00ns INFO cocotb.tb End of period count test
200000.00ns INFO cocotb.regression test_period_count passed
200000.00ns INFO cocotb.regression **************************************************************************************
** TEST STATUS SIM TIME (ns) REAL TIME (s) RATIO (ns/s) **
**************************************************************************************
** test.test_startup PASS 6000.00 0.02 362907.61 **
** test.test_reset PASS 4000.00 0.00 985504.01 **
** test.test_internal_enable PASS 4000.00 0.00 1009763.48 **
** test.test_period_count PASS 186000.00 0.11 1763647.26 **
**************************************************************************************
** TESTS=4 PASS=4 FAIL=0 SKIP=0 200000.00 0.22 918687.40 **
**************************************************************************************
make[1]: Leaving directory '/home/jesus/tt09-verilog-freqSweep/test'
Test using Tang Nano 9K FPGA (4.5 MHz input clock)
Input clock signal (yellow) and ouput clock signal (blue) acquired with an oscilloscope (analog inputs and passive probes):
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External hardware
No external hardware is needed.
IO
| # | Input | Output | Bidirectional |
|---|---|---|---|
| 0 | ui_in[0] | uo_out[0] | |
| 1 | |||
| 2 | |||
| 3 | |||
| 4 | |||
| 5 | |||
| 6 | |||
| 7 |