SN74HC164N LED blanking experiment

Read the article and the wiring figure before connecting the 5 V fixture.
Open hc164_blanking/hc164_blanking.ino in the Arduino IDE and select UNO.
The two repeated trials send the same byte, 0xA7. A direct QA probe sees
both intermediate sequences; the test LED return is disabled during the
second transfer until the completed byte is revealed.

Use observations-blank.csv for your own measurements. All worksheet
cells other than the two trial labels are blank. The timing figure is an
ideal command diagram. No hardware measurement or Arduino target run was
performed in preparation.

To check the exact supplied sketch on a computer, extract all files,
install Python 3.9+ and a C++17 compiler named c++, then run:
  python3 test_host.py
The shim models the register state and emitted pin ordering. It does not
model the MCU electrical pins, timing accuracy, LED or MOSFET behavior.
