RCC - RGB Color Cube

The RCC project is based on a pcb with an ATtiny402 and two RGB LEDs that are controlled via SPI-bus. The cube itself is controlled over a single push-button that enables/disables the cube and can be used to setup the color and intensity of the rgb leds.

Experience	Level
Soldering
Mechanical
Software

Downloads

Type	File	Description
Schematic	pdf / cadlab	Schematic files
Board	pdf / cadlab	Board file
Drill	pdf	Drill file
PCB	zip / tar	KiCAD/Gerber/BoM/Drill files
Mechanical	zip / tar	FreeCAD/Housing and PCB (STEP) files
Firmware	zip / tar	Firmware for ATtiny402

Hardware

There are two parts of the hardware. The pcb and the housing of the RCC. The pcb is created with KiCAD and the housing with FreeCAD. The software is programmed with Microchip (Atmel) Studio. All files are built with github actions so that they are ready for a production environment. The housing is printed with a 3D-printer (Dremel 3D40).

PCB

The circuit board is populated on both sides (Top, Bottom). The best way for soldering the SMD components is within a vapor phase soldering system and for the THT components with a standard soldering system.

Top Layer

Bottom Layer

Mechanical

The housing has a tolerance of 0.2mm on each side of the case. So the pcb should fit perfectly in the housing. The tolerance can be modified with FreeCAD in the Parameter Spreadsheet.

Assembled

Exploded

Programming/Setup

The RCC is powerd with a 3V battery (CR2032). It can be programmed over UPDI on TP1. The firmware for the cube can be downloaded in the download section.

#                                                          +-----------+      +---------------------+
#                                                          |    U  +---+---+  |                     |
#     +---------------------+                              |    S  |  USB  |--+ +-----------------+ |
#     |                     |                              |    B  +---+---+  | | AVR-Dude        | |
#     |    RCC - Color Cube |         +----------+         |    /      |      | | ~~~~~~~~        | |
#     |                  +--+--+   +--+--+  U    |         |    U      |      | | ~~~~~           | |
#     |              VCC | TP3 +---+ VCC |  P  +--+--+  +--+--+ A      |      | | ~~~~~~~~~~~~    | |
#     |              GND | TP2 +---+ GND |  D  | GND +--+ GND | R      |      | |                 | |
#     |                  +--+--+   +--+--+  I  | VCC +--+ VCC | T      |      | +-----------------+ |
#     |                     |         |        +-----+  +-----+ A      |      |                     |
#     |                  +--+--+   +--+--+     | RxD +--+ RxD | +------+      | Computer            |
#     |             UPDI | TP1 +---+ PDI |     | TxD +--+ TxD | |5V/3V3|      |                     |
#     |                  +--+--+   +--+--+     +--+--+  +--+--+ +------+      +---------------------+
#     +---------------------+         | ADAPTER   |        +----+------+
#                                     +-----------+

FUSES

Register	Value
WDTCFG	0x00
BODCFG	0x00
OSCCFG	0x03
TCD0CFG	0x00
SYSCFG0	0xF5
SYSCFG1	0x00
APPEND	0x00
BOOTEND	0x00

Software

The leds are controlled by SPI. The interface is displayed in the dataflow diagram. There is a pre-configured firmware to use the cube or a library to implement own solutions.

A documentation of the code can be found here https://0x007e.github.io/rcc.

Dataflow diagram

Library (led.h)

With the attached led library it is quiet easy to use the cube for own implementations. To setup the led library for the cube implement the header file.

#define F_CPU 20000000UL

#include <avr/io.h>
#include <util/delay.h>

#include "./hal/avr0/system/system.h"
#include "./led/led.h"

LED_Data led1  = {
	0x01,
	0x0F,
	0x00,
	0x0A
};

LED_Data led2  = {
	0x01,
	0x00,
	0x0F,
	0x0A
};

int main(void)
{
    system_init();
    led_init();
    // ...

    while(1)
    {
        led_blink(LED_Position_Left | LED_Position_Right_Alternating, led_status_color(LED_Status_Ready, LED_MIN_INTENSITY), LED_Delay_MS_200, 2);

        LED_SOF();
        led_data(led1);
        led_data(led2);
        LED_EOF();

        _delay_ms(2000);
    }
}

Additional Information

Type	Link	Description
ATtiny402	pdf	ATtiny microcontroller
T3A33BRG	pdf	RGB Color LED
Atmel ICE	pdf	Atmel ICE datasheet
UPDI	web	UPDI-Adapter with AVR-Dude
Microchip Studio	web	Download page for Microchip Studio
KiCAD	web	KiCAD project page
FreeCAD	web	FreeCAD project page

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R. GAECHTER