feat: add support Arduino UNO Q

BoardSupport.md

@@ -113,6 +113,24 @@ static inline void attachInterrupt(pin_size_t interruptNumber, voidFuncPtr callb
 #define PIN_TO_SERVO(p)         (p)
 ```
 
+## Arduino UNO Q
+
+The Arduino UNO Q is a Zephyr RTOS-based board built on the STMicroelectronics STM32U585AI (Cortex-M33). It uses the [arduino/ArduinoCore-zephyr](https://github.com/arduino/ArduinoCore-zephyr) core (FQBN `arduino:zephyr:unoq`), which is installed through the Arduino IDE Boards Manager after adding the package index `https://downloads.arduino.cc/packages/package_zephyr_index.json`.
+
+Unlike the classic Uno, sketches on the UNO Q are compiled to a freestanding ELF that is loaded dynamically by a precompiled Zephyr firmware. Any pin that does not appear in the variant's `pwm-pin-gpios`, `adc-pin-gpios`, `i2cs`, or `spis` devicetree properties will not be driven by the corresponding peripheral, so Firmata only exposes the Arduino R3 header pins plus the onboard RGB LED.
+
+| Property | Value |
+| ----------- | ------------------------------------ |
+| Number of Pins  | 22 user-addressable (14 digital D0-D13 + 6 analog A0-A5 as D14-D19 + 2 dedicated I2C D20/D21), plus the onboard RGB LED at `LED_BUILTIN` (pin 51) |
+| Number of analog inputs | 6 (14-bit ADC) |
+| Flash Memory | 2 MB |
+| RAM | 786 KB |
+| PWM capable pins | D2, D3, D5-D13, D20, D21, `LED_BUILTIN` (D0/D1 are reserved for USART1 and not PWM-enabled in the default variant) |
+| Built-in LED | Yes, the `led3_green` RGB channel exposed as `LED_BUILTIN`; no LED is wired to D13 |
+| I2C, Bus 0 | D20 SDA (PB11), D21 SCL (PB10) on I2C2 |
+| SPI, Bus 0 | D10 SS (PB9), D11 MOSI (PB15), D12 MISO (PB14), D13 SCK (PB13) on SPI2 |
+| Serial1 | D0 RX (PB7), D1 TX (PB6) on USART1 |
+
 ### I2C
 
 The Raspberry Pi Pico [datasheet](https://datasheets.raspberrypi.org/pico/Pico-R3-A4-Pinout.pdf) states that the

examples/ConfigurableFirmata/ConfigurableFirmata.ino

@@ -16,9 +16,10 @@ const int NETWORK_PORT = 27016;
 
 // #define ENABLE_ONE_WIRE
 
-// Note that the SERVO module currently is not supported on ESP32. So either disable this or patch the library
-#ifndef ESP32
-#define ENABLE_SERVO 
+// Note that the SERVO module currently is not supported on ESP32 or on the Zephyr-based Arduino cores
+// (e.g. Arduino UNO Q), which do not ship a Servo library. So either disable this or patch the library.
+#if !defined(ESP32) && !defined(ARDUINO_ARCH_ZEPHYR)
+#define ENABLE_SERVO
 #endif
 
 // #define ENABLE_ACCELSTEPPER
@@ -166,7 +167,12 @@ void initTransport()
 	}
 	Firmata.begin(serverStream);
 	Firmata.blinkVersion(); // Because the above doesn't do it.
-#else 
+#elif defined(ARDUINO_UNO_Q)
+	// On the Arduino UNO Q, the STM32's Serial1 is bridged to /dev/ttyHS1 on the
+	// Linux side. The default `Serial` is USB-CDC and is not reachable from Linux.
+	Serial1.begin(115200);
+	Firmata.begin(Serial1);
+#else
 	Firmata.begin(115200);
 #endif
 }

src/ConfigurableFirmata.cpp

@@ -24,6 +24,40 @@ extern "C" {
 #include <stdlib.h>
 }
 
+#if defined(ARDUINO_ARCH_ZEPHYR)
+// The Zephyr Arduino core builds sketches as LLEXTs against picolibc. libc's vsnprintf
+// is not reliably resolvable by the LLEXT loader, but Zephyr's cbvprintf is exported
+// (see ArduinoCore-zephyr loader/llext_exports.c). Wrap it to provide a drop-in
+// vsnprintf with matching semantics.
+#include <zephyr/sys/cbprintf.h>
+
+static int firmata_zephyr_vsnprintf_cb(int c, void *ctx_raw)
+{
+  struct { char *buf; size_t size; size_t pos; } *ctx =
+    (decltype(ctx))ctx_raw;
+  if (ctx->pos + 1 < ctx->size) {
+    ctx->buf[ctx->pos] = (char)c;
+  }
+  ctx->pos++;
+  return c;
+}
+
+static int firmata_zephyr_vsnprintf(char *str, size_t size, const char *fmt, va_list ap)
+{
+  struct { char *buf; size_t size; size_t pos; } ctx = { str, size, 0 };
+  // Older Zephyr headers shipped with the Arduino core declare cbprintf_cb as a
+  // K&R-style (untyped) function pointer, so cast explicitly to satisfy C++.
+  int written = cbvprintf((cbprintf_cb)firmata_zephyr_vsnprintf_cb, &ctx, fmt, ap);
+  if (size > 0) {
+    size_t term = ctx.pos < size ? ctx.pos : size - 1;
+    str[term] = '\0';
+  }
+  return written;
+}
+
+#define vsnprintf firmata_zephyr_vsnprintf
+#endif
+
 //******************************************************************************
 //* Support Functions
 //******************************************************************************

src/utility/Boards.h

@@ -802,6 +802,37 @@ static inline void attachInterrupt(pin_size_t interruptNumber, voidFuncPtr callb
 #define PIN_TO_PWM(p)           (p)
 #define PIN_TO_SERVO(p)         (p)
 
+// Arduino UNO Q (Zephyr-based, STM32U585AI, Arduino R3 pinout)
+// FQBN: arduino:zephyr:unoq (arduino/ArduinoCore-zephyr)
+#elif defined(ARDUINO_UNO_Q)
+#define TOTAL_ANALOG_PINS       6
+// LED_BUILTIN (led3_green on PH11) is index 51 in the variant's digital-pin-gpios list,
+// so TOTAL_PINS is sized to cover it even though only a subset are user-addressable.
+#define TOTAL_PINS              52
+#define TOTAL_DEFAULT_PINS      22 // 14 digital (D0-D13) + 6 analog (A0-A5 as D14-D19) + 2 I2C (D20 SDA, D21 SCL)
+#define VERSION_BLINK_PIN       LED_BUILTIN
+#define PIN_SERIAL1_RX          0
+#define PIN_SERIAL1_TX          1
+#define IS_PIN_DIGITAL(p)       (((p) >= 2 && (p) < TOTAL_DEFAULT_PINS) || (p) == LED_BUILTIN)
+#define FIRMATA_IS_PIN_ANALOG(p) ((p) >= 14 && (p) < 14 + TOTAL_ANALOG_PINS)
+// PWM-capable pins per the variant overlay's pwm-pin-gpios; D0/D1 are disabled due to the USART1 conflict.
+#define FIRMATA_IS_PIN_PWM(p)   ((p) == 2 || (p) == 3 || ((p) >= 5 && (p) <= 13) || (p) == 20 || (p) == 21 || (p) == LED_BUILTIN)
+#define IS_PIN_SERVO(p)         (IS_PIN_DIGITAL(p) && (p) - 2 < MAX_SERVOS)
+#define IS_PIN_I2C(p)           ((p) == 20 || (p) == 21) // SDA = D20 (PB11), SCL = D21 (PB10) on I2C2
+// The Zephyr Arduino core does not expose the standard PIN_SPI_* / SS / MOSI / MISO / SCK symbols,
+// so provide them here pointing at SPI2 (the bus exposed on the R3 header).
+#define PIN_SPI_SS              10
+#define PIN_SPI_MOSI            11
+#define PIN_SPI_MISO            12
+#define PIN_SPI_SCK             13
+#define IS_PIN_SPI(p)           ((p) == PIN_SPI_SS || (p) == PIN_SPI_MOSI || (p) == PIN_SPI_MISO || (p) == PIN_SPI_SCK)
+#define IS_PIN_SERIAL(p)        ((p) == 0 || (p) == 1) // USART1 on D0 (RX) / D1 (TX)
+#define PIN_TO_DIGITAL(p)       (p)
+#define PIN_TO_ANALOG(p)        ((p) - 14)
+#define PIN_TO_PWM(p)           PIN_TO_DIGITAL(p)
+#define PIN_TO_SERVO(p)         ((p) - 2)
+#define DEFAULT_ADC_RESOLUTION  14 // STM32U5 ADC runs at 14 bits per the variant devicetree
+
 // Arduino UNO R4 Minima and Wifi
 // The pinout is the same as for the classical UNO R3
 #elif defined(ARDUINO_UNOR4_MINIMA) || defined(ARDUINO_UNOR4_WIFI)