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Add basic Game of Life Sense HAT LED Matrix Example
Can change colours, update time and choose between three starting seeds: Mold, Mazing and Octagon2. Each of these patterns are periodic oscillators (they repeat) and fit inside the 8x8 matrix.
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‎examples/all/sense_hat_demo.cc

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// Copyright lowRISC Contributors.
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// SPDX-License-Identifier: Apache-2.0
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/*
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* Simple demo using the LED Matrix. Can switch between a small 8x8 Conway's
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* Game of Life example from an initial state, and displaying some text
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* sweeping across the LED matrix.
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*
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* Hold down the joystick to switch between the two demos.
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*
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* Refer to the comment on the `sense_hat.hh` library: be careful about using
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* this demo when switching software / bitstream / resetting the FPGA. If used
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* in this context, you might find that the I2C controller on the Sense HAT
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* gets stuck, and so you need to either unplug/replug the Sense HAT or power
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* cycle the FPGA.
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*/
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#include "../../libraries/sense_hat.hh"
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#include "../../third_party/display_drivers/core/m3x6_16pt.h"
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#include <compartment.h>
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#include <debug.hh>
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#include <platform-gpio.hh>
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#include <thread.h>
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/// Expose debugging features unconditionally for this compartment.
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using Debug = ConditionalDebug<true, "Sense HAT">;
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using Colour = SenseHat::Colour;
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const Colour OnColour = {.red = Colour::MaxRedValue, .green = 0, .blue = 0};
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const Colour OffColour = {.red = 25, .green = 25, .blue = 25};
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constexpr uint64_t GolFrameWaitMsec = 400;
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constexpr char DemoText[] = "CHERIoT <3 Sonata! ";
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constexpr uint64_t TextFrameWaitMsec = 150;
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/// Use a custom bitmap for "g" to make presentation slightly cleaner
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constexpr uint8_t GBitmap[8] = {
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0x00, //
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0x06, // ##
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0x05, // # #
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0x07, // ###
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0x04, // #
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0x03, // ##
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0x00, //
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0x00, //
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};
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/// Game of Life starting patterns
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constexpr bool Mold[8][8] = {
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{0, 0, 0, 0, 0, 0, 0, 0},
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{0, 0, 0, 0, 1, 1, 0, 0},
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{0, 0, 0, 1, 0, 0, 1, 0},
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{0, 0, 1, 0, 1, 0, 1, 0},
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{0, 0, 1, 0, 0, 1, 0, 0},
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{0, 1, 0, 0, 0, 0, 0, 0},
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{0, 0, 1, 0, 1, 0, 0, 0},
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{0, 0, 0, 0, 0, 0, 0, 0},
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};
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constexpr bool Octagon2[8][8] = {
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{0, 0, 0, 1, 1, 0, 0, 0},
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{0, 0, 1, 0, 0, 1, 0, 0},
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{0, 1, 0, 0, 0, 0, 1, 0},
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{1, 0, 0, 0, 0, 0, 0, 1},
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{1, 0, 0, 0, 0, 0, 0, 1},
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{0, 1, 0, 0, 0, 0, 1, 0},
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{0, 0, 1, 0, 0, 1, 0, 0},
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{0, 0, 0, 1, 1, 0, 0, 0},
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};
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constexpr bool Mazing[8][8] = {
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{0, 0, 0, 0, 0, 0, 0, 0},
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{0, 0, 0, 1, 1, 0, 0, 0},
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{0, 1, 0, 1, 0, 0, 0, 0},
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{1, 0, 0, 0, 0, 0, 1, 0},
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{0, 1, 0, 0, 0, 1, 1, 0},
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{0, 0, 0, 0, 0, 0, 0, 0},
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{0, 0, 0, 1, 0, 1, 0, 0},
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{0, 0, 0, 0, 1, 0, 0, 0},
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};
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enum class Demo : uint8_t
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{
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GameOfLife = 0,
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ScrollingText = 1,
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};
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void update_image(const bool state[8][8], Colour fb[64])
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{
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// Update the pixel framebuffer based on the current GOL game state
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for (uint8_t i = 0; i < 64u; i++)
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{
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fb[i] = state[i / 8u][i % 8u] ? OnColour : OffColour;
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}
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}
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uint8_t get_neighbours(bool state[8][8], uint8_t y, uint8_t x)
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{
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// Count neighbours
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uint8_t neighbours = 0u;
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for (int8_t ny = static_cast<int8_t>(y - 1); ny <= y + 1; ny++)
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{
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for (int8_t nx = static_cast<int8_t>(x - 1); nx <= x + 1; nx++)
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{
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if ((ny == y && nx == x) || ny < 0 || ny >= 8 || nx < 0 || nx >= 8)
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continue;
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neighbours += state[ny][nx];
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}
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}
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return neighbours;
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}
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void update_gol_state(bool state[8][8])
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{
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bool result[8][8] = {0u};
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// Iterate through cells
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for (uint8_t y = 0u; y < 8u; y++)
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{
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for (uint8_t x = 0u; x < 8u; x++)
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{
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uint8_t neighbours = get_neighbours(
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state, static_cast<int16_t>(y), static_cast<int16_t>(x));
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// Calculate the new state and store into a temporary result array
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if (state[y][x] && neighbours != 2u && neighbours != 3u)
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{
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result[y][x] = 0u;
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}
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else if (!state[y][x] && neighbours == 3u)
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{
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result[y][x] = 1u;
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}
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else
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{
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result[y][x] = state[y][x];
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}
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}
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}
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// Copy the newly calculated state back into the original 2D array
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memcpy(state, result, sizeof(bool[8][8]));
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}
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void update_text_state(bool state[8][8], uint32_t *index, uint32_t *column)
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{
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uint8_t currentChar = static_cast<uint8_t>(DemoText[*index]);
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/// If at the end of the string, reset to the beginning (wrap around)
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if (currentChar == '\0')
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{
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*index = 0;
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*column = 0;
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currentChar = static_cast<uint8_t>(DemoText[0]);
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}
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/// Copy all columns left by 1.
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for (uint8_t x = 0u; x < 7u; x++)
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{
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for (uint8_t y = 0u; y < 8u; y++)
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{
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state[y][x] = state[y][x + 1];
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}
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}
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/// Render the bitmap on the last column
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bool noBitsInColumn = true;
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for (uint8_t y = 1u; y < 8u; y++)
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{
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const uint32_t BitmapAddr = (currentChar - 32u) * 8u + y - 1u;
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const uint8_t Bit = 1u << *column;
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/// Retrieve bitmap
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if (currentChar == 'g')
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{
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state[y][7] = (GBitmap[y - 1u] & Bit) >> *column;
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}
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else
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{
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state[y][7] = (m3x6_16ptBitmaps[BitmapAddr] & Bit) >> *column;
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}
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/* (Slightly hacky): detect gaps (columns with no bits) to determine
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when the character ends, so that we can render this monospaced font
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without monospacing. This won't work for every character, but is good
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enough for our purposes. */
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if (state[y][7])
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{
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noBitsInColumn = false;
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}
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}
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/* If a gap is found, or the entire character is rendered, progress to the
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next character to render. */
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if ((noBitsInColumn && (currentChar != ' ')) || (*column == 6u))
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{
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if (++*index > sizeof(DemoText))
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{
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*index = 0;
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}
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*column = 0;
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}
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else
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{
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*column += 1;
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}
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}
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void initialize_demo(Demo currentDemo,
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bool ledState[8][8],
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uint32_t *index,
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uint32_t *column)
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{
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switch (currentDemo)
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{
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case Demo::GameOfLife:
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memcpy(ledState, Octagon2, sizeof(bool[8][8]));
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break;
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case Demo::ScrollingText:
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memset(ledState, 0u, sizeof(bool[8][8]));
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*column = 0u;
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*index = 0u;
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break;
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default:
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Debug::log("Unknown demo type to intialize: {}", currentDemo);
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break;
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}
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}
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/// Thread entry point.
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void __cheri_compartment("sense_hat_demo") test()
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{
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Debug::log("Starting Sense HAT test");
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Demo currentDemo = Demo::GameOfLife;
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// Initialise GPIO capability for joystick inputs
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auto gpio = MMIO_CAPABILITY(SonataGpioBoard, gpio_board);
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// Initialise the Sense HAT
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auto senseHat = SenseHat();
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// Initialise a blank LED Matrix.
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Colour fb[64] = {OffColour};
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senseHat.set_pixels(fb);
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// Initialise LED Matrix starting states
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bool ledState[8][8];
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uint32_t index = 0;
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uint32_t column = 0;
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bool joystickPrevPressed = false;
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initialize_demo(currentDemo, ledState, &index, &column);
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while (true)
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{
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/* If a joystick press is detected during an update, switch the demo
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type. This is not polled in a while waiting between updates, so a press
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can be missed between updates. */
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bool joystickIsPressed = static_cast<uint16_t>(gpio->read_joystick()) &
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static_cast<uint16_t>(SonataJoystick::Pressed);
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if (!joystickPrevPressed && joystickIsPressed)
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{
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currentDemo =
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static_cast<Demo>((static_cast<uint8_t>(currentDemo) + 1) % 2);
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thread_millisecond_wait(500);
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initialize_demo(currentDemo, ledState, &index, &column);
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joystickPrevPressed = true;
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}
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if (joystickPrevPressed && !joystickIsPressed)
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{
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joystickPrevPressed = false;
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}
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switch (currentDemo)
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{
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case Demo::GameOfLife:
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/// Every frame, update the game state and LED matrix.
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thread_millisecond_wait(GolFrameWaitMsec);
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update_image(ledState, fb);
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senseHat.set_pixels(fb);
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update_gol_state(ledState);
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break;
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case Demo::ScrollingText:
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/// Every frame, update the scrolling text and LED matrix
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thread_millisecond_wait(TextFrameWaitMsec);
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update_image(ledState, fb);
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senseHat.set_pixels(fb);
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update_text_state(ledState, &index, &column);
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break;
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default:
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thread_millisecond_wait(100UL);
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Debug::log("Unknown demo type: {}", currentDemo);
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}
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}
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}

‎examples/all/xmake.lua

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@@ -22,3 +22,7 @@ compartment("rgbled_lerp")
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compartment("proximity_sensor_example")
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add_deps("debug")
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add_files("proximity_sensor_example.cc")
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compartment("sense_hat_demo")
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add_deps("debug", "sense_hat")
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add_files("sense_hat_demo.cc", "../../third_party/display_drivers/core/m3x6_16pt.c")

‎examples/xmake.lua

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after_link(convert_to_uf2)
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-- Demo that uses a Sense HAT's LED Matrix
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firmware("sense_hat_leds")
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add_deps("freestanding", "led_walk_raw", "lcd_test", "rgbled_lerp", "sense_hat_demo")
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on_load(function(target)
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target:values_set("board", "$(board)")
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target:values_set("threads", {
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{
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compartment = "led_walk_raw",
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priority = 2,
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entry_point = "start_walking",
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stack_size = 0x200,
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trusted_stack_frames = 1
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},
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{
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compartment = "lcd_test",
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priority = 2,
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entry_point = "lcd_test",
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stack_size = 0x1000,
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trusted_stack_frames = 1
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},
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{
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compartment = "rgbled_lerp",
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priority = 2,
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entry_point = "lerp_rgbleds",
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stack_size = 0x200,
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trusted_stack_frames = 1
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},
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{
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compartment = "sense_hat_demo",
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priority = 2,
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entry_point = "test",
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stack_size = 0x1000,
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trusted_stack_frames = 1
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}
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}, {expand = false})
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end)
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after_link(convert_to_uf2)
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-- Demo that does proximity test as well as LCD screen, etc for demos.
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firmware("leds_and_lcd")
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add_deps("freestanding", "led_walk_raw", "lcd_test", "rgbled_lerp")

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