PickledDog

Member Since: February 11, 2013

Country: United States

  • What’s that piece of cut tape with the big chunky components on the right?

  • How is this laid out? Does it resemble resemble 4 32x32 panels laid out NW-NE-SW-SE, or is it a 64-pixel-wide 1:32 panel? I’m just curious (and concerned?)

    I see the datasheet lists this as a 1:16 panel, but I also notice that pin 8 on the HUB75 connector is marked as ‘E’, not ‘GND’. This can sometimes indicate a 1:32 scan rate.

  • I can confirm that these draw 14mA at 5V, and 5.7mA at 3.3V. Given that the red ones pull 18mA, I’d hazard a guess that the internal resistor in these is about 150Ω. At 5.7mA, this is safe to use with the SAMD21/Zero/M0 boards, although I would avoid driving one continuously.

  • I see not just a burn mark, but a board with its identifying marks masked off. I shiver with anticipation!

    (I know that companies prototype stuff all the time, and many products are dead ends. Which is why early prototypes are not revealed without masking.)

  • I’m confused. Since all interfacing is done via an ATMega328, why would this device be harmed by 5V?

  • Sounds about right. You’re gonna have a constant 3mA draw from the USB D- 1.5K/Zener combo (which is unavoidable with 5V software USB), plus whatever the MCU uses. You would have to rip the USB parts off to go any lower, and they’re kinda the whole point of this board :)

  • Sadly, it can’t. This family of Attiny chips implements SPI and I2C via a peripheral called USI (essentially the guts of a serial peripheral that provides everything you need, but doesn’t implement any specific protocol). There’s only one USI, so it can only implement one or the other. You can probably get away with bit-banging SPI for the nRF chip, though.

  • Stress relief hole. YES!

    Seriously, please put these on everything that’s likely to have directly attached wires.

  • 18mA… This is so close to being the perfect “in-breadboard” poor man’s logic probe. If it only drew less current!

    I currently solder 1K resistors into the legs of LEDs, and a source of pre-made ones would be super helpful. These “probe” LEDs can be scattered throughout a breadboard circuit to debug it, or to just visualize its workings to observers. The 2mA draw makes them essentially transparent to most modern logic components. Any chance you can request your supplier to make low current versions?

  • Heads up! These will happily pull 4A from your power supply, not 2A, due to having twice the LEDs of their 32x32 cousins.

    For those keeping score at home, this is a P4 panel, 4mm LED pitch. The other panels SparkFun carries are P6 6mm.

No public wish lists :(