Search results

  1. gorgon

    RGB controller

    This is what I would do it and not necessarily how it is done in the video. The background task will be to output a continuous formated sequence of the LED data from the data array. This is done inside the interrupt driven SPI system/controller interrupt service routine. If we use the...
  2. gorgon

    RGB controller

    From the video clip of the software, I would assume that the update of the LEDs are running completely in the background, and on interrupt. In the foreground the setup of the bit arrays are done in a much slower speed. You'll need 3 x 512 bits to update the whole cube, and the data should...
  3. gorgon

    RGB controller

    You should also be aware that increasing the number of row drivers will also increase the need for updating speed of the matrix, since your duty cycle will increase from 1/8 to 1/24. As I understand the video of the software. Each row is now shown 4 times, and this end up in 32 updates for...
  4. gorgon

    Trouble with tribbles.. erm, timers.

    What you can't do is to run 2 leads with a difference of 5V and 240V with the same small distance between the leads. You'll need at least 2.5 mm for the 240VDC between the leads. We use as a guideline 1mm/100V, 240VAC should be 3.5mm, due to the peak voltage of 340V.
  5. gorgon

    Low-leakage high-side switch?

    I wonder about the capacity of the battery you use in this project, and how long the active period is defined to last. I suppose you know that the battery needs to keep a rest charge large enough to tolerate your alarm condition load long enough. 500mA in this equation is a large load. An...
  6. gorgon

    SPI single line SDI/SDO

    From the datasheet of the MMA7455, page 18, you can see the sequence of the transfer for both read and write to the chip. The easiest way to do this is to use a diode between the PIC's SDO to the SDI/SDO line from the 7455 and connect the PIC's SDI line to this common point. The diode's cathode...
  7. gorgon

    RGB controller

    If you want to use around 20mA for each LED you should use 560ohms for the red and 470 for the other LEDs. This will give between 18 and 19 mA for each LED, when continuous on. This will also give you a bit less total current in total for your 500mA wallwart, around 340mA. More LEDs of the...
  8. gorgon

    RGB controller

    What type is the RGB LED module you use? 12V 6W is 0.5A. You can still use the 360mA LED solution, but you need to check out the controller, for how much current it's using itself. You should leave a safety margin on the current consumption, and not load much more than 400mA continuous current.
  9. gorgon

    RGB controller

    The main problem with your LEDs are that they are common anode RGB LED modules, and you need to treat them as individual LEDs in your design. If you get RGB packs with 3 separate LEDs(6 leads) you can make strings of the same colour, as proposed to reduce the total current. With the RGB...
  10. gorgon

    Component questions (transistor, capacitor)

    For SMD you can use BC817 as a general NPN transistor, and BC807 as a general PNP transistor. Both are in a SOT23 package, small but not too small to handle manually.
  11. gorgon

    need help in counter programming+ pic16f877a

    The easiest is to use a flag or semaphore to store the last value of the input. you compare the current state with that, and only do the + when the input change from an old '0' to a new '1'. You store the new value as the flag, whenever there is a change. Using this procedure, you can implement...
  12. gorgon

    Trouble with tribbles.. erm, timers.

    Well you should be since you want to do this display system. I'll break it down. 24x20x18x50 = 432000bps: SPI controllers always send whole bytes so 18 bits is expanded to 24 bit for the 18 rows. You want to have a colour depth of 20, so you need to repeat the above 20 times for each...
  13. gorgon

    Multitasking an Arduino

    Any microcontroller can only do one thing at any time, but it can be made to do those things so fast that it looks like it is doing several things at the same time. I've made many such systems or programs during my worklife. One really important this to remember i such a system, is that you...
  14. gorgon

    Trouble with tribbles.. erm, timers.

    You still need an update frequency of 24x20x18x50 = 432000bps to achieve this, not including the single step column driver pulses. That's a fast SPI. You'll need 1080 bytes to store 1 frame of data(3x20x18) If you reduce the number of colour from 8000 to 512 = 8 steps, you'll gain a lot of...
  15. gorgon

    Component questions (transistor, capacitor)

    The Vce over the BC557 is typical 0.2V, worst cas 0.6V. If we assume 0.3V we should be safe. This leaves 4.7V for the LED. If you want to run 1mA in the Red LED @Vfwd 1.8V. you'll need to drop 2.9V @ 1mA, which is the same as 2k9 for the value. You can use 2k7 to simulate this. If you...
  16. gorgon

    1.2 V Power Supply Voltage drop

    Ok, then you should go through your selection of components around U4 and U1. If you look into the datasheet for the tps61010, you'll see the R15/16 on your design is way too low in value, the recommended value of the R15 is 500k and then the R16 should be 1M for a 1.5V output. The same goes...
  17. gorgon

    Trouble with tribbles.. erm, timers.

    For shiftregisters with drivers, I've used UCN5818EPF from Allegro. This is a 32bit wide SPI shiftregister with source drivers. I don't know if this family is still alive but there were several variants with different bit lengths.
  18. gorgon

    1.2 V Power Supply Voltage drop

    What types of ICs are the U4 and U1 in circuit 2? I can't really see why you feed circuit 2 with 1.2V. Any specification of the requirements of this circuit?
  19. gorgon

    Component questions (transistor, capacitor)

    Many points for good effort, close but no cigar. :) Please find attached my proposal, based on your info. Note that Rled will be different for each colour to get the same current. 4k7 = 4700 ohm
  20. gorgon

    Trouble with tribbles.. erm, timers.

    What is the update frequency and the dutycycle for the current setup? If the output is continuous, you can't really see the effect of multiplexing on the light. The reason for the high current is that you short the output(s) of the 595. The current is only limited by the output driver...
Top