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CIRCUIT NOTEBOOK Interesting circuit ideas which we have checked but not built and tested. Contributions will be paid for at standard rates. All submissions should include full name, address & phone number. Conway’s Game of Life on the Micromite In 1970, mathematician John Horton Conway devised The Game of Life. It illustrates how complex patterns can be created by very simple rules. This has many parallels in the natural world. The Game is based on an infinite 2D grid of square cells. Thus, each cell has eight neighbours. Four simple rules are then applied: 1. If a live cell has one or no neighbours, it dies through loneliness or under-population. 2. If a live cell has two or three neighbours, it lives on to the next generation. 3. If a live cell has four or more neighbours, it dies through over-population or overcrowding. 4. If a dead cell has exactly three neighbours, it is born by reproduction. An initial pattern of live cells is entered into the grid, and the Game is started. The Game then steps through siliconchip.com.au each generation. Some patterns die out quickly, some become stable, and others multiply indefinitely. For more information, see https://w.wiki/3TKJ I have developed two versions of the Game of Life. The first runs on the Micromite LCD BackPack with the 2.8in ILI9341-based touchscreen and does not require any additional hardware. In addition to several pre-defined starting patterns, the user can create their own. The second is designed as a standalone PCB (using the circuit shown here) with a small 0.96in IPS display, and it can be used as an interactive display with the addition of two pushbuttons or an infrared (IR) remote control. Alternatively, it can operate in fully automatic mode, taking about 55 minutes to complete an entire cycle of all the preset starting patterns. This can be incorporated as wearable jewellery Australia's electronics magazine such as a brooch, or in other novelty applications. The software driver for the IPS display was written by Peter Mather and edited by Peter Carnegie – see www. thebackshed.com/forum/ViewTopic. php?TID=7137 While the original Game was designed for an infinite 2D grid of cells, in the Micromite version, the grid is limited to 32 x 24 cells for the BackPack version or 32 x 20 cells for the smaller IPS display. There is the option for cells to drop off the edge of the display, or wrap around from one side to the other. The best choice depends on how the initial pattern develops. For the circuit of the BackPack-based version, see one of the BackPack articles. The standalone version shown here uses the same PIC32MX170F256B-50I/SP microcontroller programmed with the Micromite software, plus a simple power supply and the 0.96in ST7735S-based 80 x 160 pixel January 2022  61 The circuit built on a home-etched PCB at upper left, with two close-up shots of the display in action. The software and PCB gerber files can be downloaded from siliconchip.com.au/Shop/6/6085 IPS display. The display is controlled using the SPI protocol via eight connections: • GND and Vcc supply 3.3V. • SCL (SCK in SPI mode) and SDA (SDI in SPI mode) are the two SPI protocol pins that connect to pin 25 (SPI Clock) and pin 3 (SPI out) on the PIC chip, respectively. • RES, DC and CS are control signals connected to pins 23, 22 and 21 on the PIC. • BLK is the backlight control pin. It is not used in this application. The power supply is a simple 3.3V linear regulator. An infrared (IR) receiver or two push buttons (or both) can optionally be connected to control the display. The IR receiver connects to pin 16 on the micro. If installed, you can access the menu of preset demonstration patterns. The optional pushbuttons connect to pins 9 and 10. They provide forward and backward scrolling through the menu of preset demonstration patterns. Alternatively, pin 9 or 10 (or both) can be permanently connected to ground by fitting a wire link in place of the switch. In this case, the display runs in automatic mode, scrolling through each of the pre-defined starting patterns in turn as soon as the power is applied. Pins 9 and 10 have weak internal pull-up currents and thus do 62 Silicon Chip not require external pull-up resistors. In operation Both versions start automatically when power is applied. With the BackPack version, you can select the various pre-defined starting patterns by using the up and down arrows on the touchscreen. Touching the screen whilst the Game is running returns to the menu. There is also the option of defining your own starting pattern by touching individual cells on the screen. Each touch toggles a cell on or off. In this case, a small red square at the bottom right-hand corner acts as an Enter and Start key. As mentioned above, the standalone version uses the IR receiver or pushbuttons to move through the starting patterns menu. Pressing the ‘next’ and ‘previous’ remote control buttons scroll through the menu of preset demonstration patterns. Pressing any other button on the remote selects the menu item. Pressing the ‘next’ or ‘previous’ button whilst the Game is running returns to the menu. You can set up your remote control codes without amending the program by pressing any key on your remote control while the initial screen is displayed. You will then be asked to press the key you want to assign to ‘next’ and then the one you want to assign to ‘previous’. These are then stored in non-volatile memory so that they will be preserved when the power is removed. Alternatively, set the constants IR_ device, IR_next and IR_previous in the Micromite program to match the codes produced by your remote control. With the pushbutton version, holding the pushbutton scrolls through the menu items and releasing the pushbutton selects the menu item. Pressing a button while the Game is running returns to the menu. Kenneth Horton, Woolston, UK. ($150) Circuit Ideas Wanted Got an interesting original circuit that you have cleverly devised? We will pay good money to feature it in Circuit Notebook. We can pay you by electronic funds transfer, cheque or direct to your PayPal account. Or you can use the funds to purchase anything from the SILICON CHIP Online Store, including PCBs and components, back issues, subscriptions or whatever. Email your circuit and descriptive text to editor<at>siliconchip.com.au Australia's electronics magazine siliconchip.com.au