Extend 'set_blink_rate()' to turn off display with value of '-1'

[mungewell]

I have a project with multiple modules, when 'blink()' was enabled they blinked a slightly different rates... which looked funky.

The register for blinking also includes a 'display_on' bit, so I access that with a vaule of '-1' to turn off the display(s). Set a normal blink rate to turn display(s) back on.

Tested on the 'HT16K33Segment' from Adafruit.

[mungewell]

I realized that it would be more useful if repeated writes of '-1' toggled the display off, on, off, on. That way the app wouldn't need to track the state.

I'll revise the patch tonight...

[smittytone]

I'm going to hold off on this PR and look at other ways to implement this functionality. I don't think set_blink_rate() should be used as a proxy for turning the display on or off, as that's a side effect not indicated by the function's name. For example, I'd rather add display_on()/display_off functions, which make what they do explicit.

[smittytone]

See the develop branch for how it's looking

[mungewell]

I adapted your test script for multiple displays:
test_multiple_segment14_ecbuying_054.py.txt

And added a blink check with .display_on() , which failed. I think it is confusing function/variable of the same name

MPY: soft reboot
Address 0x70 Display Found.
Address 0x71 Display Found.
Address 0x72 EIO error (Errno 5): Check connections.
Address 0x73 EIO error (Errno 5): Check connections.
Address 0x74 EIO error (Errno 5): Check connections.
Address 0x75 EIO error (Errno 5): Check connections.
Address 0x76 EIO error (Errno 5): Check connections.
Address 0x77 EIO error (Errno 5): Check connections.
Total 2 Displays found
Traceback (most recent call last):
  File "<stdin>", line 108, in <module>
TypeError: 'bool' object isn't callable

PS. True is/was not capitalized in the assert...