SparkFun Qwiic Alphanumeric Display

[gigapod]

Board

SparkFun Qwiic Alphanumeric Display

Notes

• Existing Driver

[sfe-SparkFro]

Tested most examples on XRP, the driver appears to work fine.

Most examples have wrong example index (eg. print statements, comments, etc.)

Example 4 uses my_display.display_print(), but display_print() is not defined, looks like it was a typo for just print()

Haven't tested Example 8 and 9, need a second display

[sfe-SparkFro]

Tested on XBee as well, all good!

[faludi]

Circling back to this one to start tracking down some issues I noticed earlier. I'm having no luck with set_colon_off() and set_decimal_off(). Also the shift_left() and shift_right() don't operate as expected when strings are longer than the current display (I'm only working with a single display right now so > 4 characters). In fact doing a .print() to the display with strings longer than the 4 character positions appears to overwrite it rather than truncating at 4 characters. Can you confirm you are seeing the same issues?

import qwiic_alphanumeric
import time

my_display = qwiic_alphanumeric.QwiicAlphanumeric()
my_display.begin()

my_display.decimal_on()
print('decimal on')
time.sleep(2)
my_display.decimal_off()
print('decimal off')
time.sleep(2)
my_display.colon_on()
print('colon on')
time.sleep(2)
my_display.colon_off()
print('colon off')
time.sleep(2)
my_display.clear()
print('clear')
time.sleep(1)
my_display.print('ABCD')
print('ABCD')
time.sleep(2)
for _ in range(4):
    my_display.shift_left()
    time.sleep(1)
time.sleep(2)
my_display.print('Hello World')
print('Hello World')
for _ in range(4):
    my_display.shift_left()
    time.sleep(1)
time.sleep(2)
print('Done')

[sfe-SparkFro]

Thanks Rob! I'm seeing the same behavior, so I'll take a look.

[sfe-SparkFro]

Ok, I think I've got these figured out with working solutions.

set_colon_off() and set_decimal_off() - Apparently the bit that enables these was never actually getting cleared. This bug has existed for >2 years in the Aruduino library, I'm surprised no one's found it until now (and that it was clearly not tested!).

Long print() and shift_left() and shift_right() - This seems like a gray area between bug vs. "feature", but I'm leaning more towards bug. The current library implementation just wraps around when printing longer strings, which is why it draws over the previous characters. As for the character shifting, the current implementation only stores as many characters as are available (4 with a single display), so shifting will always loose characters. It's possible to increase that buffer size, but then the question becomes how big to make it? The library can handle up to 4 displays connected, so I think the simplest solution is to just store 16 characters (the library actually does this under the hood, so it's a fairly simple code change). Let me discuss with @gigapod on what we want to do with regards to that.

[sfe-SparkFro]

@faludi Ok, fixes have been rolled out: sparkfun/qwiic_alphanumeric_py#5

set_colon_off() and set_decimal_off() should now work as expected.

Long inputs to print() will now limit to the number of characters available (eg. 4 characters with 1 display, 8 characters with 2 displays, etc.)

Additionally, only the number of characters that are available will be remembered, which effects shift_left() and shift_right(). So for example, if you run the following:

my_display.print('1234')
my_display.shift_right()
my_display.shift_left()
my_display.shift_left()
my_display.shift_right()

The display will only show 23 (with spaces on either side). This may not be what is expected, but the problem is determining how many characters to store; if the user passes "Hello world" or a whole paragraph of Lorem Ipsum, should the library really remember the whole thing? Probably not. So you'd instead just need to manually change the start index of that string to get the same scrolling effect. Example:

my_string = "Hello world"
for i in range(12):
    my_display.print(my_string[i:])
    time.sleep(1)

Please let me know how it goes, and if you run into any other issues!