Add hsync and vsync signals for 480x640 resolution

.gitignore

@@ -2,3 +2,4 @@ build/
 .cache
 .direnv
 pico_sdk_import.cmake
+compile_commands.json

flake.lock

@@ -1,5 +1,23 @@
 {
   "nodes": {
+    "flake-utils": {
+      "inputs": {
+        "systems": "systems"
+      },
+      "locked": {
+        "lastModified": 1731533236,
+        "narHash": "sha256-l0KFg5HjrsfsO/JpG+r7fRrqm12kzFHyUHqHCVpMMbI=",
+        "owner": "numtide",
+        "repo": "flake-utils",
+        "rev": "11707dc2f618dd54ca8739b309ec4fc024de578b",
+        "type": "github"
+      },
+      "original": {
+        "owner": "numtide",
+        "repo": "flake-utils",
+        "type": "github"
+      }
+    },
     "nixpkgs": {
       "locked": {
         "lastModified": 1771369470,
@@ -18,8 +36,8 @@
     },
     "root": {
       "inputs": {
-        "nixpkgs": "nixpkgs",
-        "systems": "systems"
+        "flake-utils": "flake-utils",
+        "nixpkgs": "nixpkgs"
       }
     },
     "systems": {
@@ -32,8 +50,9 @@
         "type": "github"
       },
       "original": {
-        "id": "systems",
-        "type": "indirect"
+        "owner": "nix-systems",
+        "repo": "default",
+        "type": "github"
       }
     }
   },

flake.nix

@@ -1,51 +1,41 @@
 {
-  inputs.nixpkgs.url = "github:nixos/nixpkgs/nixos-unstable";
+  inputs = {
+    nixpkgs.url = "github:nixos/nixpkgs/nixos-unstable";
+    flake-utils.url = "github:numtide/flake-utils";
+  };
 
   outputs =
-    inputs @ { nixpkgs
-    , systems
+    { nixpkgs
+    , flake-utils
     , ...
     }:
+    flake-utils.lib.eachDefaultSystem (system:
     let
-      inherit (nixpkgs) lib;
-      eachSystem = lib.genAttrs (import systems);
-      pkgsFor = eachSystem (system:
-        import nixpkgs {
-          localSystem = system;
-        });
+      pkgs = import nixpkgs { inherit system; };
+      pico-sdk = pkgs.pico-sdk.override {
+        withSubmodules = true;
+      };
+      PICO_SDK_PATH = "${pico-sdk}/lib/pico-sdk";
     in
     {
-      devShells =
-        eachSystem
-          (system: {
-            default =
-              let
-                pkgs = pkgsFor.${system};
-                pico-sdk = pkgs.pico-sdk.override {
-                  withSubmodules = true;
-                };
-                PICO_SDK_PATH = "${pico-sdk}/lib/pico-sdk";
-              in
-              pkgs.mkShell {
-                name = "PicoVGA dev shell";
-                inputsFrom = [ pico-sdk ];
-                packages = with pkgs;
-                  [
-                    gcc-arm-embedded
-                    python3
+      devShell = pkgs.mkShell {
+        name = "PicoVGA dev shell";
+        inputsFrom = [ pico-sdk ];
+        packages = with pkgs; [
+          gcc-arm-embedded
+          python3
+          pico-sdk
 
-                    usbutils
-                    picotool
-                    picocom
-                  ]
-                  ++ [ pico-sdk ];
+          picocom
 
-                shellHook = ''
-                  ln -sf ${PICO_SDK_PATH}/external/pico_sdk_import.cmake pico_sdk_import.cmake
-                '';
+          usbutils
+          picotool
+        ];
+        shellHook = ''
+          ln -sf ${PICO_SDK_PATH}/external/pico_sdk_import.cmake pico_sdk_import.cmake
+        '';
 
-                inherit PICO_SDK_PATH;
-              };
-          });
-    };
+        inherit PICO_SDK_PATH;
+      };
+    });
 }

src/main.cpp

@@ -1,25 +1,42 @@
 #include "hardware/gpio.h"
 #include "pico/stdlib.h"
+#include <pico/time.h>
+
+#include <concepts>
 #include <cstdint>
 #include <cstdio>
-#include <pico/time.h>
 
 constexpr static uint start_pin = 2;
 constexpr static uint pin_mask = (0xFFF) << start_pin;
 
+template <std::integral T> constexpr bool between(T x, T min, T max) {
+  return (x >= min) && (x < max);
+}
+
 int main() {
   stdio_init_all();
 
   for (uint offset{}; offset != 14; ++offset) {
     auto const pin = start_pin + offset;
+    std::printf("Initializing GPIO %d\n", pin);
     gpio_init(pin);
     gpio_set_dir(pin, GPIO_OUT);
   }
 
-  for (uint16_t pixel{};; ++pixel) {
-    auto const set_mask = (pixel & 0xFFF) << start_pin;
-    printf("Set mask=%03x", pixel);
-    gpio_put_masked(pin_mask, set_mask);
-    sleep_ms(100);
+  for (uint32_t y{}; y != 525; ++y) {
+    for (uint32_t x{}; x != 800; ++x) {
+      const auto is_blanking = y >= 480 || x >= 640;
+      const auto hsync = between(x, 656ul, 752ul);
+      const auto vsync = between(y, 490ul, 492ul);
+
+      auto const pixel = (0u << 8) | ((y & 0xF) << 4) | (x & 0xF);
+      auto const set_mask =
+          (((uint32_t)vsync << 13) | ((uint32_t)hsync << 12) | (pixel & 0xFFF))
+          << start_pin;
+
+      std::printf("Set mask=%04X\n", set_mask >> start_pin);
+      gpio_put_masked(pin_mask, set_mask);
+      sleep_ms(10);
+    }
   }
 }