TicTacLightsNanoColourEnglish

project overview
Year	2017
Number of pixels	144
Grayscales / Colors	512
Illuminant	SMD LEDs (size 0404)
Power input	? mW
Contact person	Arne Rossius
Project website

TicTacLights Nano Colour is the RGB version of TicTacLights Nano, which also fits into a mini TicTac box. Just like the monochrome version, it uses a lithium polymer battery, alternatively it can be powered from USB. The LEDs are square and only 1 x 1 mm large.

This project uses the BlinkenPlus firmware on an ATmega162 controller.

Hardware

The hardware is split onto two stacked PCBs, the main board and the power/data board. The main board (4 layers with blind vias) contains the LEDs, the microcontroller, the shift register ICs and the associated transistors and passives. It also contains the Micro-USB connector for mechanical reasons. The power/data board (2 layers) contains the USB to UART bridge IC, a switching converter (to generate the 5 V supply required for the RGB LEDs when using battery power) and battery charger IC as well as the MicroSD card slot. The two boards are connected through a 1.5 mm high fine-pitch connector.

Start-up Problems

Hardware revisions 1.0 and 1.1 (all kits sold before 2021) often have an issue at power-on, all LEDs remain dark. This is caused by the shift registers outputting "low" on all pins at power-on. This causes all MOSFETs to conduct, which puts all 18 pull-down resistors of 220 Ω each across the supply in parallel. The boost converter for the 5 V supply isn't able to start up with this much load, the output voltage stops rising when it reaches around 2 V — not enough for the microcontroller.

This problem can be solved by increasing the pull-down resistors (R7~R11) to 470 Ω. A suitable type is e.g. Yageo YC164-JR-07470RL (available in single quantities from Reichelt with order code "BCN16 470" — ignore their picture, it is wrong).

Rev. 1.2

In Rev. 1.2, R7~R11 were increased to 470 Ω. PCBs and solder paste stencils remain unchanged.

• Schematic (PNG)
• Construction kit instructions Rev. 1.2

Rev. 1.1

Only the solder paste stencils changed for Rev. 1.1.

• Stencils for main board (Gerber)
• Stencils for power/data board (Gerber)

Rev. 1

• Schematic (PNG)
• PCB layout for main board (Gerber/Excellon)
• PCB layout for power/data board (Gerber/Excellon)
• Construction kit instructions Rev. 1.1

Software

This project uses the BlinkenPlus firmware.

Photos

http://arne.blinkenarea.org/TicTacLights%20Nano%20Colour/gallery.htm