Windell Oskay

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  • in reply to: Nokia PCD8544 (5110 LCD display) is a little strange #20738
    Windell Oskay
    Keymaster

    I’m afraid that I don’t have any personal experience with this LCD.   

    Have you followed the Adafruit tutorial on wiring and programming this display ( http://ladyada.net/products/nokia5110/ ) ?   They also have a support forum for LCD display issues, which is probably the best place to ask questions like these ( http://forums.adafruit.com/viewforum.php?f=47 ). There are several questions in the forums there that may be related, and it stands to reason that other people who have been through these issues do frequent these forums.
    -Windell 
    in reply to: Help With Programming Meggy Jr RGB #20746
    Windell Oskay
    Keymaster

    Have you been able to get some of the existing simple demos to work, such as MeggyJr_CheckButtonsPress and MeggyJr_EasyDrawDots?  

    in reply to: Custom solder pad in .fp (gEDA) #20737
    Windell Oskay
    Keymaster

    So far as I know, this cannot be done directly.  It looks like general polygons can’t be part of footprints. 

    However, building it out of lines is actually a pretty good workaround.  I was able to draw an open star with just five line segments (six clicks total!), which seems to convert into an element just fine.  With a fatter line width (and about 30 seconds), I was able to fill the shape with lines, making a solid star shape. And that works as an element too.  Not half bad, actually. :)
    in reply to: FTDI USB-TTL cable or breakout board #20729
    Windell Oskay
    Keymaster

    From what I can tell, that uses the same chip, so it will be compatible.  (Our own store carries a similar board, the FTDI Friend, which is basically the same but with the addition of a few configuration options.)

    Windell Oskay
    Keymaster

    Well, “maybe.”

    In our demo, we used a current-controlled transistor.  High-power LED drivers may or may not be able to accept and respond to a fast control signal (depending on whether or not they are designed for PWM), and if so, you’ll likely have to adapt the control signal input to the type that they’re expecting.
    in reply to: One very bright unresponsive row on Peggy 2 #20726
    Windell Oskay
    Keymaster

    By “low-voltage position” I just meant that it was held electrically low (close to ground).

    > the positive pin of every LED in row 1 is in continuity with the emitter pin (right-most) of EVERY transistor. 

    This should not be the case; compare with the other rows.  The emitter of the transistors is connected to the positive power supply (“Vcc”), and Vcc should not (directly) make it into the LED matrix anywhere.  The likely issue is that the collector (middle pin) of Q1 is connected to the emitter.  Check on the top and bottom sides of the PCB for a short at Q1.  If you cannot find an external short, try replacing that transistor. 
    in reply to: One very bright unresponsive row on Peggy 2 #20724
    Windell Oskay
    Keymaster

    If I understand correctly, whenever an LED lights anywhere, the LED in row 1 but in the same column as that LED lights up as well.  That suggests that the transistor on row 1 is stuck in the “on” position.  Using your multimeter, check to see if the base pin of Q1 (the left-most pin, connected to RB1) is stuck in the low-voltage position.  If so, it’s likely that the transistor is OK, but is receiving a bad signal.  Check to see if that pin is electrically connected to nearby things.  Then, check the other end of RB1 to see if it might be shorted to pins 2 or 20 of U2.  It *should* be connected to pin 3 of U2, and that pin alone.

    in reply to: One very bright unresponsive row on Peggy 2 #20721
    Windell Oskay
    Keymaster

    >Using the continuity tester on my multimeter, when powered on, the + and – leads of the LEDS on Row 1 are continuous. 


    I’m not sure what you mean by “continuous” here.  The square-hole sides are connected together in every row, and the round-hole sides are connected together in every column.

    >Row 1 is not ALWAYS all lit.  When the device is powered on, an apparently random pattern of LEDS in Row 1 sometimes light (usually in blocks of three or four) with a few LEDS in between not lit  My earlier statement that the LEDS show no response at all to the sketch may be incorrect.  I can see them flickering slightly but they are so bright it’s hard to be sure.

    Have you finished building the Peggy yet, or are you still trying to debug it while building?  If there’s a pattern in the behavior, it is likely to reveal itself more clearly when all of the LEDs are in.  And, if something is flaky, try wiggling the different components to see if the transistor or one of the chips has an intermittent connection.

    in reply to: Alpha Clock Five Case #20733
    Windell Oskay
    Keymaster

    >There is no scroll-bar on this window so I can’t see anthing that won’t fit on one screen.

    Hmmm. Most web pages do not have built-in scroll bars. How do you *normally* scroll down a web page?
    (I use the scroll wheel, trackpad, or page-down key.)

    in reply to: Alpha Clock Five Case #20731
    Windell Oskay
    Keymaster

    Good catch!  I’ve added it to the wiki page. :D

    in reply to: help needed to in getting Meggy RGB Jr. going (newbies) #20718
    Windell Oskay
    Keymaster

    Yes, that sounds like what I’d do.  :)

    in reply to: New Diavolino #20735
    Windell Oskay
    Keymaster

    I’d suggest attaching the battery box via the USB 6-pin connector, using a 6-pin female header socket strip.   Since you have the USB power jumper installed, you probably don’t need to run both power and USB at the same time.

    in reply to: help needed to in getting Meggy RGB Jr. going (newbies) #20716
    Windell Oskay
    Keymaster

    If you managed to damage the first LED D1 when you soldered it in, you may want to be a little more gentle with your soldering– those don’t usually fail.

     

    pc1

    The connection of button b1 to pin PC1 is shown above.   If you’re reading 0 V on that pin, then it is likely that there’s a bad connection between the two points.  Check to see if there is actually a connection between these two points. (You can do that from the top or bottom of the board.)  
    gnd
    One pin of button b1 is connected to ground.  Check to see if it is actually connected, say to the pin to the left of PC0.
    Then, check to see if this pin is electrically connected to the PC0 when the button is and is not pressed.
    in reply to: One very bright unresponsive row on Peggy 2 #20719
    Windell Oskay
    Keymaster

    It is likely that you have a short circuit somewhere in the control section that is holding the base of one of the transistors low– or just connecting it to a neighboring signal.  This could be either at the transistor itself (which you have already checked) or at the pins of U2, the LED driver that controls the second row.   If you have access to a multimeter, you might be able to use that to help locate the issue.  

    in reply to: help needed to in getting Meggy RGB Jr. going (newbies) #20714
    Windell Oskay
    Keymaster

    The correct behavior on startup is that D0, D1, D2, D3, and D4 should light up.  So, it’s not that some of your LEDs are shifted, it’s just that one of them is not lighting up.  Check the soldering at that LED location, and at the pins of the LED driver chips.  Also make sure that that D1 is installed with the correct orientation.

    Check the soldering at button “A” (aka location b1 on the circuit board) and the corresponding pin of the microcontroller, which is the pin located directly above the hole labeled PC1.  
    You may also want to download the Meggy Jr RGB schematic, to help figure out where to put the multimeter, if you want to do this that way:   http://wiki.evilmadscience.com/Meggy_Jr_RGB
Viewing 15 posts - 1,411 through 1,425 (of 1,426 total)