LED Cube 8x8x8

Step 51 Software: IO initialization

The first thing the ATmega does after boot, is to call the ioinit() function.

This function sets up IO ports, timers, interrupts and serial communications.
All IO ports on the ATmega are bi-directional. They can be used either as an input or an output. We configure everything as outputs, except the IO pins where the two buttons are connected. The RX pin for the serial line automatically becomes an input when USART RX is enabled.

1) DDRx sets the data direction of the IO pins. (Data Direction Register). 1 means output, 0 means input.

2) After directionality has been configured, we set all outputs to 0 to avid any blinking LEDs etc before the interrupt has started.

3) For pins configured as inputs, the PORTx bit changes its function. Setting a 1 in the PORTx register bit enables an internal pull up resistor. The port is pulled up to VCC. The buttons are connected between the port and GND. When a button is pressed the corresponding PINx bit reads a logic 0.

4) Timer 2 is configured and a timer interrupt enabled. This is covered in a separate step.

5) Serial communications is configured and enabled. This is also covered in a separate step.

Comments

[b_ovalle28]

I have downloaded the source code and am trying to "make all" in WinAVR and it is saying::: undefined reference to 'launch_effect'-----line56
::: undefined reference to 'delay_ms'----line 173 & 185
::: undefined reference to 'tmp2cube'----line 256
How do I clear these errors?

[triumphtotty]

Do you have all of the .c and .h files in the same folder as Makefile? Those files are the only ones referenced by main.c, so I suspect you only have main.c/.h being compiled. There should be Makefile, cube.h, draw.c/.h, effect.c/.h font.c/.h gameoflife.c/.h, launch_effect.c/.h and main.c and .h in the folder.

[flunk2003]

Hey, I have built a cube following your fantastic instructable. I loaded the test file and everyting works fine (after an afternoon of adjusting). But when I load the main.hex and main.eeprom file you have provided I run into a problem. The cube won't start any animations, pressing the RS232-button doesn't light up the linked led and the upper reset button doesn't work either. But when I change the code you provided in main to not start the bootwait program (so immediately start with the programmed effects) the cube doesn't do anything for 40 seconds, and start suddenly to play the effects, starting with effect box shrink grow (case 6). After some effects (about 2-3 minutes) the cube suddenly stops and I have to reset it to replay the effects. Does anyone have an idea what could be wrong. I guess it's a hardware problem but I've checked and don't find any problems. Where should I look?

altered code: int main (void) { ioinit(); current_layer = 1; int i; for (i=0; i<EFFECTS_TOTAL; i++)
   launch_effect(i);

[flunk2003]

I've checked al the connections and located the problem. I misconnected the buttons, so the system was continuously being restarted. There was a direct connection instead of a button. After switching the buttons (2 out of 3 were wrong) the cube worked!

Thanks for the replies.

[troller1]

1. Try checking your connections and contacts
2. Probably you should add two pull-up resistors to your buttons. This instructable has a program enabling internal ATMega pull-ups, but they're very weak (about 100K), you should use 10K. Also check you have such a resistor on your ATMega RESET pin, and be sure you connected all VCC and GND pins.
3. Try replacing your ATMega.
4. Pressing the RS232-button will not light up the LED, it will lit only when you send something to UART. And check your ATMega pins 14 and 15, there's a mistake in this instructable and these pins have to be flipped.

[hybrid_snyper]

Just guessing, could it be a watchdog timer?