make it compile for esp32-wroom-32

.envrc

@@ -0,0 +1 @@
+use nix;

shell.nix

@@ -0,0 +1,57 @@
+{
+  pkgs ? import <nixpkgs> { },
+}:
+let
+  host-triple = "x86_64-unknown-linux-gnu";
+  gcc-arch = "xtensa-esp-elf";
+  gcc-release = "16.1.0_20260609";
+  toolchain-pkg = pkgs.stdenv.mkDerivation rec {
+    pname = "esp32-xtensa-rust-toolchain";
+    version = "1.97.0.0";
+    srcs = [
+      (pkgs.fetchurl {
+        url = "https://github.com/esp-rs/rust-build/releases/download/v${version}/rust-${version}-${host-triple}.tar.xz";
+        hash = "sha256-qZv+5pIh6f9thjiPaBHuaIzUBeagQAo80XhOjUY+nZk=";
+      })
+      (pkgs.fetchurl {
+        url =
+          let
+            gcc-file = "${gcc-arch}-${gcc-release}-x86_64-linux-gnu.tar.xz";
+          in
+          "https://github.com/espressif/crosstool-NG/releases/download/esp-${gcc-release}/${gcc-file}";
+        hash = "sha256-9wh1Lrs1yrIfGEsldBFO0Rh2GdsO24pLqRPAbKL6Z14=";
+      })
+      (pkgs.fetchurl {
+        url = "https://github.com/esp-rs/rust-build/releases/download/v${version}/rust-src-${version}.tar.xz";
+        hash = "sha256-Vo1oi5+PMy7E0EZXVE+tI+mc4R6ebPWDWXnmiijGi3M=";
+      })
+      # TODO maybe I need clang but so far it works without https://github.com/esp-rs/espup/blob/main/src/toolchain/llvm.rs
+    ];
+    sourceRoot = ".";
+    nativeBuildInputs = [ pkgs.autoPatchelfHook ];
+    buildInputs = [
+      pkgs.zlib
+      pkgs.stdenv.cc.cc.lib
+    ];
+    installPhase = ''
+      runHook preInstall
+
+      patchShebangs --build rust-nightly-x86_64-unknown-linux-gnu/install.sh rust-src-nightly/install.sh
+
+      rust-nightly-x86_64-unknown-linux-gnu/install.sh --destdir="$out" --prefix="" --without=rust-docs-json-preview,rust-docs --disable-ldconfig
+      rust-src-nightly/install.sh --destdir="$out" --prefix="" --disable-ldconfig
+
+      cp -pr --reflink=auto -- xtensa-esp-elf "$out";
+      # ensure linker is in PATH
+      ln -s $out/xtensa-esp-elf/bin/* "$out/bin/"
+
+      runHook postInstall
+    '';
+  };
+in
+(pkgs.mkShell {
+  packages = with pkgs; [
+    espflash
+    toolchain-pkg
+  ];
+})

src/bin/main.rs

@@ -60,24 +60,12 @@ fn main() -> ! {
     let config = esp_hal::Config::default().with_cpu_clock(CpuClock::max());
     let peripherals = esp_hal::init(config);
 
-    // The following pins are used to bootstrap the chip. They are available
-    // for use, but check the datasheet of the module for more information on them.
-    // - GPIO0
-    // - GPIO3
-    // - GPIO45
-    // - GPIO46
-    // These GPIO pins are in use by some feature of the module and should not be used.
-    let _ = peripherals.GPIO27;
-    let _ = peripherals.GPIO28;
-    let _ = peripherals.GPIO29;
-    let _ = peripherals.GPIO30;
-    let _ = peripherals.GPIO31;
-    let _ = peripherals.GPIO32;
-    let _ = peripherals.GPIO33;
-    let _ = peripherals.GPIO34;
-    let _ = peripherals.GPIO35;
-    let _ = peripherals.GPIO36;
-    let _ = peripherals.GPIO37;
+    let sck = peripherals.GPIO18;
+    let mosi = peripherals.GPIO23;
+    let miso = peripherals.GPIO19;
+    let cs_main = peripherals.GPIO5;
+    let dc = peripherals.GPIO17;
+    let reset_main = peripherals.GPIO16;
 
     esp_alloc::heap_allocator!(#[esp_hal::ram(reclaimed)] size: 73744);
 
@@ -96,16 +84,16 @@ fn main() -> ! {
             .with_mode(Mode::_0),
     )
     .unwrap()
-    .with_sck(peripherals.GPIO36)
-    .with_mosi(peripherals.GPIO35)
-    .with_miso(peripherals.GPIO37);
+    .with_sck(sck)
+    .with_mosi(mosi)
+    .with_miso(miso);
 
-    let cs_main = Output::new(peripherals.GPIO11, Level::High, OutputConfig::default());
+    let cs_main = Output::new(cs_main, Level::High, OutputConfig::default());
 
     let mut delay = Delay::new();
     let spi_dev = ExclusiveDevice::new(spi_bus, cs_main, delay).unwrap();
-    let reset_main = Output::new(peripherals.GPIO10, Level::High, OutputConfig::default());
-    let spi_dc = Output::new(peripherals.GPIO12, Level::High, OutputConfig::default());
+    let reset_main = Output::new(reset_main, Level::High, OutputConfig::default());
+    let spi_dc = Output::new(dc, Level::High, OutputConfig::default());
     let iface = SPIInterface::new(spi_dev, spi_dc);
 
     let mut display = Ili9341::new(