Update display details and communication decision

hardware/pico-pinout.md

@@ -1,17 +1,48 @@
 # Pico Pinout (Planned)
 
-Display:
-- SPI Touchscreen
+## Display
 
-Communications:
-- RS-485 Interface
+3.5 inch SPI capacitive touchscreen
 
-Inputs:
-- Touchscreen
+Resolution:
+- 320x480
 
-Future:
-- Physical Wake Button
-- Rotary Encoder
+Display Driver:
+- ST7796S
+
+Touch Controller:
+- FT6336U
+
+Display Communication:
+- SPI
+
+Touch Communication:
+- I2C
+
+Voltage:
+- 3.3V / 5V compatible
+
+## Communications
+
+Primary:
+- UART over CAT5
+
+Backup/Future:
+- RS-485 over CAT5 if UART proves unreliable
+- WiFi HTTP backup
+
+## Inputs
+
+- Capacitive touchscreen
+
+## Outputs
+
+- Active 5V buzzer for audible alarms
+- Display backlight control if supported
+
+## Future
+
+- Physical wake button
 - Status LED
 
-Final pin assignments pending touchscreen testing.
+Final pin assignments pending display wiring test.