docs: build using Nix

README.md

@@ -1,12 +1,12 @@
-# raspi demo for oled(ssd1306)
+# raspi demo for oled ssd1306 display
-
-in rust
 
 ## Quick start
 
-> docker pull ragnaroek/rust-raspberry:1.39.0
+> nix-shell
 >
-> ./build.sh
+> rustup target add arm-unknown-linux-musleabihf
+>
+> cargo build --release --target arm-unknown-linux-musleabihf
 
 Then scp the release file to your raspi.
 

build.sh

@@ -1,6 +0,0 @@
-#! /bin/sh
-docker run \
-  --volume $PWD:/home/cross/project \
-  --volume $HOME/.cargo/registry:/home/cross/.cargo/registry \
-    ragnaroek/rust-raspberry:1.39.0 \
-    build --release

shell.nix

@@ -0,0 +1,7 @@
+with (import <nixpkgs> {});
+mkShell {
+  nativeBuildInputs = [
+    pkgsCross.muslpi.stdenv.cc
+  ];
+  CARGO_TARGET_ARM_UNKNOWN_LINUX_MUSLEABIHF_LINKER = "${pkgsCross.muslpi.stdenv.cc}/bin/armv6l-unknown-linux-musleabihf-ld";
+}