I haven't got a hue

ErlendErlend Posts: 605
edited 2020-03-22 - 17:25:46 in Propeller 1
I would like to control a single WS2812B to set its hue - using it as a status indicator. It would only need to be set/changed when events occur - every few seconds or so. I am PASM-blind, and after having waded through a number of drivers I have found, trying to simplify and extract exactly what I need, I am thinking I am spending too much time getting nowhere. Can anyone help me with a simple solution? - ideally SetHue(pin, hue), where hue is a pointer to a long having the value $RR_GG_BB_WW

Note, I am approaching my 32k limit for the total project, so I need to avoid extensive driver objects.



  • JonnyMacJonnyMac Posts: 6,576
    edited 2020-03-22 - 17:52:26
    The problem is with timing; the signaling required to the WS2812B must be very precise, and it cannot be done in straight Spin. My driver -- which I'm guessing you've seen -- is very popular and has a lot of extra features that you don't need. If you're compiling with Propeller Tool, there's good news: you can run the code through BST which will strip out the unused methods and save a lot of space. I did this with a commercial lasertag project.

    An interesting development with the P2 is that you can implement small sections of PASM2 in your Spin code. I used this to create a no-frills output routine for WS2812s.

    Again, this is Spin2:
    pub ws2812b(pin, count, p_colors) | outval, t0, t1, tc, cycle
    '' Assumes 24-bit colors are MSB aligned (red in byte3)
      t0 := (clkfreq / 1_000_000) *  400 / 1000 - 6                 ' 0 bit timing
      t1 := (clkfreq / 1_000_000) *  800 / 1000 - 6                 ' 1 bit timing
      tc := (clkfreq / 1_000_000) * 1250 / 1000                     ' cycle ticks @ 800kHz
                            drvl    pin                             ' make output
                            waitx   t0                              ' allow reset
    led_loop                rdlong  outval, p_colors                ' get color
                            add     p_colors, #4                    ' point to next
                            mov     cycle, outval                   ' swap R & G bytes
                            shr     cycle, #16
                            setbyte outval, cycle, #3
                            shr     cycle, #8
                            setbyte outval, cycle, #2
                            getct   cycle                           ' start timing frame
                            rep     @.bitz, #24                     ' 8 bits x 3 colors
                            rol     outval, #1              wc      ' get MSB
                            drvh    pin                             ' pin on
            if_nc           waitx   t0                              ' hold for bit timing
            if_c            waitx   t1
                            drvl    pin                             ' pin off
                            addct1  cycle, tc                       ' update cycle timer
                            waitct1                                 ' let cycle finish
                            djnz    count, #led_loop                ' do next LED
    It wouldn't be a direct translation but you could pull the PASM code from your favorite driver and stick it into your main object with a couple methods to start and stop it. Since your code is controlling the LED color, all the methods normally included in a standard smart LED object could be chucked out. You can also save a bit of space in the PASM by changing the byte order you send to the driver. Many drivers use RR_GG_BB_WW to simplify creating constants, but the PASM code has to swap the red and green bytes. If you send GG_RR_BB_XX to the embedded driver then you can save a bit of code there.
  • JonnyMacJonnyMac Posts: 6,576
    edited 2020-03-22 - 20:16:29
    Since talk is cheap and we're on lock-down in LA, anyway, I stripped my pixel driver down the essentials and stuck it into a framework program.

    I wrote the code a bit more generically than you asked. You can add your set_hue() method like this:
    pub set_hue(pin, rgbx) | color
      color.byte[3] := rgbx.byte[2]                                 ' red/green swap
      color.byte[2] := rgbx.byte[3]
      color.byte[1] := rgbx.byte[1]
      ws2812b_update(pin, 1, @color)
  • Thanks a lot, it is now running. I took the color 'table' from your (full blown) driver and shuffled around the R and G values so that I could use them direct with
    ws2812b_update(pin, 1, @color)
    The WHITE2 did not seem to work for this led, so I took that one out. For anyone interested this is the table:
     '                  GG RR BB WW
      BLACK      LONG  $00_00_00_00
      RED        LONG  $00_FF_00_00
      GREEN      LONG  $FF_00_00_00
      BLUE       LONG  $00_00_FF_00
      WHITE      LONG  $FF_FF_FF_00
      CYAN       LONG  $FF_00_FF_00
      MAGENTA    LONG  $00_FF_FF_00
      YELLOW     LONG  $FF_FF_00_00
      CHARTREUSE LONG  $FF_7F_00_00
      ORANGE     LONG  $60_FF_00_00
      PINK       LONG  $5F_FF_5F_00
      TURQUOISE  LONG  $E0_3F_C0_00
      INDIGO     LONG  $00_3F_7F_00
      VIOLET     LONG  $7F_BF_BF_00
      MAROON     LONG  $00_32_10_00
      BROWN      LONG  $06_0E_00_00
      CRIMSON    LONG  $28_DC_3C_00
      PURPLE     LONG  $00_8C_FF_00

    Also in lockdown.
  • JonnyMacJonnyMac Posts: 6,576
    edited 2020-03-23 - 15:34:52
    Remember, the full-blown driver can accommodate several devices, including 4-chip LEDs like the SK6812RBGW for which WHITE2 is intended.

    Have fun, and stay healthy.
  • Jon, you're a good man in a storm!
  • Chartruese if by land, aquamarine if by sea, maroon for shelter in place!?
  • JonnyMac wrote: »
    Remember, the full-blown driver can accommodate several devices, including 4-chip LEDs like the SK6812RBGW for which WHITE2 is intended.

    Have fun, and stay healthy.

    Thanks, and double thanks, and same good wishes to you.
  • ErlendErlend Posts: 605
    edited 2020-03-23 - 18:35:06
    Chartruese if by land, aquamarine if by sea, maroon for shelter in place!?

    I am tempted to continue your color prose... but now's dinner time. Chartreuse by the way is also the name and color of a very nice liquor made traditionally by French monks.
  • What for the hue and cry?

    I've been involved with projects where status or event needed to be communicated, and in most cases subtlety in color discrimination was not desirable. For one example, wildland fire fighters carried an armband that indicated threshold levels of smoke exposure. The simple green, yellow and red had to be supplemented with a geometric pattern formed of several LEDs, green dot, yellow square, bright red X, so that the meaning could be picked up at a glance. Also, so that persons with red/green or other color blindness would have a primary que besides the hue. I've used a single RGB Led for similar purposes, where the additional que of what is true was a flashing or pulsating pattern.
  • ErlendErlend Posts: 605
    edited 2020-03-24 - 09:30:52
    "In common law, a hue and cry is a process by which bystanders are summoned to assist in the apprehension of a criminal who has been witnessed in the act of committing a crime."

    I do not plead guilty.
    My 'hue indicator' is not the primary (or critical) source of information. It is intended as a 'shortcut', such that when the user (repeatedly) want to make a menu selection, a hue is visible accordingly. The user will/can after a while, having noticed the association of a hue with a menu item, simply turn the knob until the desired hue is shone, and push the knob to activate. Or - for the color blind - continue to read the menu text before making a selection.
  • I was curious about the distinct meanings and etymology of hue. Sorry, you are not in the dock! I first thought that hue as coupled with cry might be related to something like the Spanish verb huir, to run away or flee. There is a hue and cry in the world now. But sources trace hue vaguely to another root that means, to cry out. For color, Google says, Old English hīw, hēow (also ‘form, appearance’, obsolete except in Scots), of Germanic origin; related to Swedish hy ‘skin, complexion’. The sense ‘color, shade’ dates from the mid 19th century.

    I can see your scheme nicely in context with a display shortcut. I don't mean to criticize! I'm interested and have used RGB leds (but not the smart kind) for color signals too, coupled with a text display and sound cues. It is effective and a lot of fun to play with. A university project on "behavioral intervention" even got to the point of using a focus group to parse the colors and sounds.
  • In Norwegian we have the verb 'huie' which means something like shouting/chasing/calling for attention. Seems to fit with 'hue and cry'.
    I also have fun experimenting with different combinations of sensory communication (been looking for a simple smell-generator, but may have to build it myself) in order to connect man-machine on a more intuitive level.
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