diff --git a/pico/.gitignore b/pico/.gitignore
index bea566b..e3974e3 100644
--- a/pico/.gitignore
+++ b/pico/.gitignore
@@ -1,3 +1,4 @@
+build
 .venv
 typings
 src/secret.py
\ No newline at end of file
diff --git a/pico/Makefile b/pico/Makefile
index 24842cd..beac495 100644
--- a/pico/Makefile
+++ b/pico/Makefile
@@ -1,6 +1,27 @@
+SRC_DIR := src
+BUILD_DIR := build
+
+SRC_FILES := $(wildcard $(SRC_DIR)/*.py) $(wildcard $(SRC_DIR)/**/*.py)
+BUILD_FILES := $(patsubst $(SRC_DIR)/%.py,$(BUILD_DIR)/%.mpy, $(SRC_FILES))
+	
+$(BUILD_DIR)/%.mpy: $(SRC_DIR)/%.py
+	@mkdir -p `dirname $@`
+	mpy-cross $< -o $@
+
+.PHONY: build
+build: $(BUILD_FILES)
+
+.PHONY: clean
+clean:
+	rm -rf $(BUILD_DIR)
+
 .PHONY: deploy
-deploy:
-	mpremote fs cp src/* :
+deploy: $(BUILD_FILES)
+	mpremote fs cp -r $(BUILD_DIR)/* :
+	
+.PHONY: purge
+purge:
+	mpremote run purge.py
 
 .PHONY: run
 run: deploy
diff --git a/pico/README.md b/pico/README.md
index 08eba16..af5b628 100644
--- a/pico/README.md
+++ b/pico/README.md
@@ -1,6 +1,20 @@
 # Setup:
-```
-$ python -m venv .venv
-$ source .venv/bin/activate
-$ pip install -U micropython-rp2-pico_w-stubs --no-user --target typings
-```
+1. Set up the virtual environment:
+   ```
+   $ python -m venv .venv
+   $ source .venv/bin/activate
+   ```
+
+2. Install the type stubs:
+   ```
+   $ pip install -U micropython-rp2-pico_w-stubs --no-user --target typings
+   ```
+
+3. Ensure `mpy-cross` is available:
+   ```
+   $ git clone https://github.com/micropython/micropython.git /tmp/micropython
+   $ pushd /tmp/micropython/mpy-cross
+   $ make
+   $ mv build/mpy-cross ~/.local/bin/
+   $ popd
+   ```
\ No newline at end of file
diff --git a/pico/purge.py b/pico/purge.py
new file mode 100644
index 0000000..a0bea29
--- /dev/null
+++ b/pico/purge.py
@@ -0,0 +1,14 @@
+import os
+
+def rm(p: str, cwd: str = "/"):
+    path = cwd+p
+    print(f"rm {path=}")
+    try:
+        os.unlink(path)
+    except OSError:
+        for f in os.listdir(path):  # pyright: ignore[reportAny]
+            rm(f, path+"/")  # pyright: ignore[reportAny]
+        os.unlink(path)
+
+for f in os.listdir():  # pyright: ignore[reportAny]
+    rm(f)  # pyright: ignore[reportAny]