cleanup to do multiple test builds

examples/AutoProvision/platformio.ini

@@ -1,8 +1,9 @@
 ; Self-contained PlatformIO project for the AutoProvision example.
 ;
-; Two host boards are provided — pick one with -e:
+; Host boards are provided — pick one with -e:
 ;     pio run -e esp32-s3-devkitc-1 -t upload   # generic ESP32-S3 dev board
 ;     pio run -e xiao-esp32s3       -t upload   # Seeed XIAO ESP32-S3
+;     pio run -e xiao-esp32c3       -t upload   # Seeed XIAO ESP32-C3
 ;     pio device monitor
 ;
 ; The radio region is set via build flags — the same LORA_* defines you'd use
@@ -50,3 +51,14 @@ build_flags =
     ; the monitor sees output. (The devkit doesn't need this; it has a CP2102.)
     -D ARDUINO_USB_MODE=1
     -D ARDUINO_USB_CDC_ON_BOOT=1
+
+[env:xiao-esp32c3]
+extends = common
+board = seeed_xiao_esp32c3
+build_flags =
+    ${common.build_flags}
+    ; host UART pins to the companion (XIAO C3 pads D7=GPIO20 RX, D6=GPIO21 TX)
+    -D UART_RX_PIN=20
+    -D UART_TX_PIN=21
+    ; native USB only (USB-Serial/JTAG) — route Serial to USB-CDC for the monitor
+    -D ARDUINO_USB_CDC_ON_BOOT=1