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michaellee1019:ht16k33

A Viam module that controls LED segment displays based on ht16k33/vk16k33 chips. This module is a Viam wrapper around the Adafruit_CircuitPython_HT16K33 library. The model has also been tested and works with the vk16k33 family of components which functionality is similar to the ht16k33.

Model: seg_14_x_4

This component supports 14-segment LED devices that have a four character display in each device. Depending on the device you can chain multiple displays together on the same channel, usually by soldering contacts that change the i2c address. Put each device address into the address array when wanting to string together the characters in each display, in the order that they are physically positioned from left to right.

This model implements the adafruit_ht16k33.segments.Seg14x4 API

Supported Hardware

Note: Other hardware may work, but may have different segment mappings to the ht16k33/vk16k33. You should be able to use the set_digit_raw command to set the segments for your specific display.

Example Config

{
      "model": "michaellee1019:ht16k33:seg_14_x_4",
      "name": "segments",
      "type": "generic",
      "attributes": {
        "address": ["0x70","0x71"]
      },
      "depends_on": []
}

Example Do Commands:

Marquee

Marquee text across the display once. Repeating marquee is currently not supported.

{
  "marquee": {
    "text": "MICHAELLEE1019"
  }
}

Marquee text with a custom time between scrolls, in seconds

{
  "marquee": {
    "text": "MICHAELLEE1019",
    "delay": 0.1
  }
}

Print

Print text onto the display. This method does not clear existing characters so it is recommended to pad the text with space chacters.

{
  "print": {
    "value": "ELLO POPPET"
  }
}

Print number. Optionally, provide decimal to round the number to a specific number of points.

{
  "print": {
    "value": 3.14159265,
    "decimal": 2
  }
}

Note: printing characters onto the display is pushed to the end of the display. If you send a single character, it will be placed in the right most digit, pushing any existing characters to the left. To clear the display, you can send space characters to print, or always send a string of characters matching the number of digits in the display.

Set Digit Raw

To get finer control over the display, you can set the raw bitmask for a specific digit. index is the index of the digit to set (0-3), and bitmask is a two byte integer from 0 to 65535 where each bit represents a segment of the display from 1-16.

The most logical way to pass in the bitmask is as a binary string. The bits in the string represent a single segment of the display. The bits are ordered depending on the specific wiring of the segments on the display. The usual order is reverse alphabetical such asN-M-L-K-J-H-G-F-E-D-C-B-A. You should check the datasheet of the display you are using to confirm the order. Seriously though, there is a ton of variation in how the segments are wired. Some displays will have two "A", and/or two "D" segments, and/or some with two "G" segments. The different display models will have different bit masks.

Using the Adafruit 0.54" Quad Alphanumeric FeatherWing Display for example, the following various bitmasks will light up the display in different ways:

Bitmask Result
0b000000000000000 Turn off all segments
0b000000000000001 Lights up segment A
0b000000000000010 Lights up segment B
... ...
0b001000000000000 Lights up segment M
0b010000000000000 Lights up segment N
0b100000000000000 Lights up segment Decimal Point (DP)
0b111111111111111 Lights up all segments

The DoCommand payload to display a 0 on the second digit of a 14x4 display would be:

{
  "set_digit_raw": {
    "index": 1,
    "bitmask": "0b000000000111111"
  }
}