1 files changed, 68 insertions, 0 deletions
diff --git a/src/xwing_sensor/main.py b/src/xwing_sensor/main.py
new file mode 100644
index 0000000..41402e6
--- /dev/null
+++ b/src/xwing_sensor/main.py
@@ -0,0 +1,68 @@
+#!/usr/bin/env python3
+"""
+Reads temperature and humidity from an SI7021 sensor (I2C) and renders
+the values to a Waveshare 2.13 inch e-Paper HAT.
+
+The Waveshare EPD library (waveshare_epd) is not bundled in this repo.
+See README.md for setup instructions.
+"""
+import time
+
+from smbus2 import SMBus
+from PIL import Image, ImageDraw, ImageFont
+from waveshare_epd import epd2in13_V4  # adjust module name for your HAT version
+
+I2C_BUS = 1
+I2C_ADDR = 0x40
+POLL_INTERVAL = 120  # seconds between display refreshes
+
+
+def read_si7021(bus: SMBus) -> tuple[float, float]:
+    """Return (temp_c, humidity_pct) from the SI7021 sensor."""
+    rh_raw = bus.read_i2c_block_data(I2C_ADDR, 0xE5, 2)  # measure RH, hold master
+    time.sleep(0.1)
+    humidity = ((rh_raw[0] * 256 + rh_raw[1]) * 125 / 65536.0) - 6
+
+    temp_raw = bus.read_i2c_block_data(I2C_ADDR, 0xE3, 2)  # measure temp, hold master
+    time.sleep(0.1)
+    temp_c = ((temp_raw[0] * 256 + temp_raw[1]) * 175.72 / 65536.0) - 46.85
+
+    return temp_c, humidity
+
+
+def render(epd: epd2in13_V4.EPD, temp_c: float, humidity: float) -> None:
+    """Draw sensor readings on the e-paper display.
+
+    The 2.13in HAT is 122×250 px (portrait). We create a landscape image
+    (250×122) by swapping width/height, which matches the typical Waveshare
+    example convention of passing (epd.height, epd.width) to Image.new.
+    """
+    image = Image.new("1", (epd.height, epd.width), 255)  # 255 = white background
+    draw = ImageDraw.Draw(image)
+
+    font_large = ImageFont.load_default(size=40)
+    font_small = ImageFont.load_default(size=22)
+
+    draw.text((10, 8), f"{temp_c:.1f} \u00b0C", font=font_large, fill=0)
+    draw.text((10, 62), f"{humidity:.1f} % RH", font=font_small, fill=0)
+
+    epd.display(epd.getbuffer(image))
+
+
+def main() -> None:
+    epd = epd2in13_V4.EPD()
+    epd.init()
+    epd.Clear()
+
+    bus = SMBus(I2C_BUS)
+    try:
+        while True:
+            temp_c, humidity = read_si7021(bus)
+            render(epd, temp_c, humidity)
+            time.sleep(POLL_INTERVAL)
+    except KeyboardInterrupt:
+        epd.sleep()
+
+
+if __name__ == "__main__":
+    main()