Document UART as primary communication method

docs/uart.md

@@ -2,18 +2,18 @@
 
 ## Overview
 
-The first hardware version will use plain UART over CAT5 between the Pico dashboard and the ESP32 cargo controller.
+The first hardware version will use UART over CAT5 between the Pico dashboard and the ESP32 controller.
 
-UART is simpler than RS-485 and should be reliable enough for the short cable run inside the Xterra.
+UART is simpler than RS-485 and should be reliable for the short cable run inside the Xterra.
 
-RS-485 remains a fallback if UART proves unreliable.
+RS-485 remains a future fallback if testing reveals communication issues.
 
 ## Architecture
 
 Pico Dashboard
-↓
-UART over CAT5
-↓
+|
+| UART over CAT5
+|
 ESP32 Controller
 
 Backup:
@@ -26,60 +26,45 @@ RS-485 over CAT5
 
 Pico TX -> ESP32 RX
 Pico RX <- ESP32 TX
-Ground  <-> Ground
+Ground <-> Ground
 
 ## Planned Baud Rate
 
 Initial:
-115200 baud
+115200
 
-Future testing:
-- 57600 baud if noise becomes an issue
-- 230400 baud if higher update rates are needed
+Future Options:
+- 57600
+- 230400
 
 ## Message Format
 
-Messages will use newline-delimited JSON.
-
-Example request:
+Newline-delimited JSON
 
+Request:
 {"type":"status_request"}
 
-Example response:
-
-{"type":"status_response","data":{"battery":{"soc":82}}}
-
-Each message ends with a newline character.
+Response:
+{"type":"status_response"}
 
 ## Failure Handling
 
-If no valid response is received within the timeout:
+If communication is lost:
 
-- Dashboard shows communication warning
+- Dashboard shows warning
 - Last known values remain visible
 - Relay commands fail safely
-- WiFi backup may be attempted if enabled
+- WiFi backup may be attempted
 
-## Why UART First
-
-Advantages:
+## Advantages
 
 - Fewer parts
-- Easier wiring
 - Easier debugging
-- No direction-control pin
-- No transceiver modules required
-- Works well over short distances
+- Easier wiring
+- No transceivers
+- No direction control
+- Works well for short runs
 
-## Why RS-485 Is Still Available
+## Future RS-485 Option
 
-RS-485 may be used later if UART has issues caused by:
-
-- Alternator noise
-- Relay switching noise
-- Fridge compressor noise
-- Inverter noise
-- Long cable run
-- Ground noise
-
-The software should keep a transport abstraction so UART and RS-485 can be swapped without changing the application protocol.
+If vehicle electrical noise causes issues, the transport layer can be switched to RS-485 without changing application logic.