Frequently Asked Questions

How much power does the LED-Matrix need?

The Matrix consists of 64 RGB LEDs and each LED needs about 60mA (3 * 20mA) at full brightness. Therefore the maximum current is 64 * 0.06A = 3.8A.

How is the ATtiny85 connected to the RPi?

The ATtiny85 is connected via SDA+SCL (I2C) to the Raspberry Pi.

Can the Raspberry Pi control the WS2812 LEDs directly?

For direct control of the WS2812 LEDs from the Raspberry Pi have a look at the examples from: 626Pilot and jgarff. The jumper next to the reset switch has to be closed to position 18. Then the data input of the first WS2812 LED is connected to GPIO18 of the Raspberry Pi.

How to flash/update the ID EEPROM?

The EEPROM on the HAT can be updated as follows. Before the update the WP jumper next to the EEPROM has to be closed.

  • Install EEPROM utils:

    $ git clone --depth=1
    $ cd hats/eepromutils
    $ make
    $ chmod +x
  • Generate EEPROM data:

    $ wget
    $ ./eepmake rpi-ws2812-hat.txt rpi-ws2812-hat.eep
  • Update/Flash EEPROM:

    $ sudo ./ -w -t=24c32 -f=rpi-ws2812-hat.eep

    Note: For a Device Tree Kernel add to /boot/config.txt the following line before flashing: dtparam=i2c0=on (before any dtoverlay statement).