This repository documents the collaborative work of MaibornWolff and intuity for an ATMEGA based calling card for one of our events.
This calling card holds an implementation of the classic "Simon Says"-Memory Game, where you have to remember an increasing sequence of button presses. The design implements multiple features:
- Allowing for sequences of up to 15, which are suprisingly difficult
- Different animations on the 4 installed LEDs, using the PWM pins of the microcontroller
- Persistend highscore tracking with EEPROM
- Energy saving with smart sleep modes
The hardware design is based around the ATMEGA328P and is quite similar to a stripped down version of the Arduino Pro Mini. We use a small CR1220 battery cell - though we found out that (some) CR1225 batteries also fit the socket and have a little more mAh - to deliver 3V of power to the device, which results in surprisingly long battery lives (greater than an hour of play time).
The Software is simple C code created with arduino studio. We use a custom bootloader to use the internal 8Mhz clock, this saves us one part on the BOM and we do not need the full clock accuracy anyway. The current code is ~350 lines of code. Most of the lines are being used by functions that improve the overall usability and cover edge cases. After compilation, the binary uses around ~20% of the available flash memory, so if you have any cool ideas feel free to contribute or create your own firmware!
The calling card can be reflashed with a different source code using the Arduino IDE and a FTDI to USB stick. This requires some minor preparation in your IDE setup:
- Download the "atmega328p_internal_clock_bootloader" from this repository and move it to the Arduino IDE's hardware folder. The path is usually the same for MacOS and Windows: "/Users/YOUR_NAME/Documents/Arduino/hardware/".
- After restarting the IDE, you should find a new entry in your "Board" section called "atmega328p_internal_clock" with one sub-entry called "ATMEGA328 (8 MHz interal clock)".
On the hardware side, we'll be using a FTDI to USB stick (SparkFun FTDI Basic) on the vertical 6-pin header on the boards left side. You could either solder pins to these, use a 2.54 mm grid pogo-pin clamp or put male jumper wires through these holes while applying a bit of pressure from the side to make good contact.
The connections are (from top to bottom):
| Calling Card | FTDI Usb Stick |
|---|---|
| GND | GND |
| GND | CTS |
| VIN | 3V3 |
| RX | TX |
| TX | RX |
| DTR | DTR |
To flash new code, simply select the newly installed Board in your IDE, select the FTDI stick's port and upload your code as if it was a stock Arduino board. The programmer remains on the default ("AVRISP mkll").