Are you ready? Really ready? Cause here comes the Adafruit Grand Central featuring the Microchip ATSAMD51. This dev board is so big, it's not named after a Metro train, it's a whole freakin' station!
5V USB power input, 500mA fuse, protected for PC USB ports
DC barrel jack input, 800mA on 5V/3.3V rails, 2A on Vin, no fuse, only affected by on/off switch
Higher of DC jack or USB voltage (9V if 9V DC plugged in; 5V if USB only)
5V regulator output (DC) or USB passthrough, ~500mA (USB) / ~800mA (DC)
3.3V regulator output, 500mA peak
Common ground
Green power LED, indicates 5V rail
Yellow USB serial TX activity LED
Yellow USB serial RX activity LED
Red LED connected to D13, user-controllable
I2C data pin, also D20, no internal pullup (add 2.2K-10K external)
I2C clock pin, also D21, no internal pullup (add 2.2K-10K external)
General purpose GPIO
General purpose GPIO, PWM capable
General purpose GPIO, PWM capable
General purpose GPIO, PWM capable
General purpose GPIO, PWM capable
General purpose GPIO, PWM capable
General purpose GPIO, PWM capable
General purpose GPIO, PWM capable
General purpose GPIO
General purpose GPIO, PWM capable
General purpose GPIO
General purpose GPIO, PWM capable, connected to red LED (L)
GPIO #0, Serial1 RX (hardware UART), not used by USB-Serial so free to use
GPIO #1, Serial1 TX (hardware UART), not used by USB-Serial so free to use
GPIO #14, SERCOM5 TX (Mega-compat)
GPIO #15, SERCOM5 RX (Mega-compat), also I2S MCK
GPIO #16, SERCOM1 TX (Mega-compat)
GPIO #17, SERCOM1 RX (Mega-compat)
GPIO #18, SERCOM4 TX (Mega-compat)
GPIO #19, SERCOM4 RX (Mega-compat)
GPIO #20, I2C data (same as top SDA)
GPIO #21, I2C clock (same as top SCL, original Mega had separate I2C)
ADC input + DAC0 (true analog output, 0-3.3V, independent of A1)
ADC input + DAC1 (true analog output, 0-3.3V, independent of A0, PWM capable)
ADC input + GPIO, 12-bit native resolution, PWM capable
ADC input + GPIO, 12-bit native resolution
ADC input + GPIO, 12-bit native resolution
ADC input + GPIO, 12-bit native resolution
ADC input + GPIO, 12-bit native resolution
ADC input + GPIO, 12-bit native resolution
ADC input + GPIO, 12-bit native resolution
ADC input + GPIO, 12-bit native resolution
ADC input + GPIO, 12-bit native resolution
ADC input + GPIO, 12-bit native resolution
ADC input + GPIO, 12-bit native resolution, PWM capable
ADC input + GPIO, 12-bit native resolution
ADC input + GPIO, 12-bit native resolution
ADC input + GPIO, 12-bit native resolution, PWM capable
Hardware SPI clock (2x3 header), shared with D52, keep free for high-speed SPI
Hardware SPI MOSI (2x3 header), shared with D51, keep free for high-speed SPI
Hardware SPI MISO (2x3 header), shared with D50, keep free for high-speed SPI
5V output (not 3.3V)
General purpose GPIO
General purpose GPIO
General purpose GPIO
General purpose GPIO
General purpose GPIO, also PCC DEN1 (camera)
General purpose GPIO, also PCC DEN2 (camera)
General purpose GPIO, also PCC CLK (camera)
General purpose GPIO, also PCC XCLK (camera)
General purpose GPIO, also PCC D7 (camera)
General purpose GPIO, also PCC D6 (camera), I2S DI
General purpose GPIO, also PCC D5 (camera), I2S DO
General purpose GPIO, also PCC D4 (camera), I2S FS
General purpose GPIO, also PCC D3 (camera)
General purpose GPIO, also PCC D2 (camera)
General purpose GPIO, also PCC D1 (camera)
General purpose GPIO, also PCC D0 (camera)
General purpose GPIO, also PCC D9 (camera)
General purpose GPIO, also PCC D8 (camera)
General purpose GPIO, also PCC D11 (camera)
General purpose GPIO, also PCC D10 (camera)
General purpose GPIO, also PCC D13 (camera)
General purpose GPIO, also PCC D12 (camera)
General purpose GPIO
General purpose GPIO, PWM capable
General purpose GPIO
General purpose GPIO
General purpose GPIO, PWM capable
General purpose GPIO
GPIO, shared with middle SPI header MISO
GPIO, shared with middle SPI header MOSI
GPIO, shared with middle SPI header SCK
GPIO, legacy Mega SPI secondary-select
Parallel capture camera data enable 1 (fixed mapping to D26)
Parallel capture camera data enable 2 (fixed mapping to D27)
Parallel capture camera clock (fixed mapping to D28)
Parallel capture camera external clock (fixed mapping to D29)
Parallel capture camera data bit 0 (fixed mapping to D37)
Parallel capture camera data bit 1 (fixed mapping to D36)
Parallel capture camera data bit 2 (fixed mapping to D35)
Parallel capture camera data bit 3 (fixed mapping to D34)
Parallel capture camera data bit 4 (fixed mapping to D33)
Parallel capture camera data bit 5 (fixed mapping to D32)
Parallel capture camera data bit 6 (fixed mapping to D31)
Parallel capture camera data bit 7 (fixed mapping to D30)
Parallel capture camera data bit 8 (fixed mapping to D39)
Parallel capture camera data bit 9 (fixed mapping to D38)
Parallel capture camera data bit 10 (fixed mapping to D41)
Parallel capture camera data bit 11 (fixed mapping to D40)
Parallel capture camera data bit 12 (fixed mapping to D43)
Parallel capture camera data bit 13 (fixed mapping to D42)
I2S master clock (fixed mapping to D15)
I2S frame sync (fixed mapping to D33)
I2S serial clock (fixed mapping to D14)
I2S data out (fixed mapping to D32)
I2S data in (fixed mapping to D31)
8 MB QSPI flash, 6 dedicated pins (4x data lines), not accessible on GPIO headers
Single RGB LED (pin 88 Arduino / board.NEOPIXEL CircuitPython), used for bootloader/CircuitPython status
Micro SD card slot on dedicated SPI port (SPI1 in Arduino)
Reset button, double-tap to enter UF2 bootloader
| Pin | Position | Type | Function | Voltage |
|---|---|---|---|---|
| USB | usb | power | 5V USB power input, 500mA fuse, protected for PC USB ports | 5V |
| DC Jack | dc-jack | power | DC barrel jack input, 800mA on 5V/3.3V rails, 2A on Vin, no fuse, only affected by on/off switch | 6-12V |
| Vin | vin | power | Higher of DC jack or USB voltage (9V if 9V DC plugged in; 5V if USB only) | 5-12V |
| 5V | 5v | power | 5V regulator output (DC) or USB passthrough, ~500mA (USB) / ~800mA (DC) | 5V |
| 3V | 3v | power | 3.3V regulator output, 500mA peak | 3.3V |
| GND | gnd | ground | Common ground | 0V |
| ON | on-led | led | Green power LED, indicates 5V rail | 5V |
| TX | tx-led | led | Yellow USB serial TX activity LED | 3.3V |
| RX | rx-led | led | Yellow USB serial RX activity LED | 3.3V |
| L | l-led | led | Red LED connected to D13, user-controllable | 3.3V |
| SDA | sda-top | digital io | I2C data pin, also D20, no internal pullup (add 2.2K-10K external) | 3.3V |
| SCL | scl-top | digital io | I2C clock pin, also D21, no internal pullup (add 2.2K-10K external) | 3.3V |
| D2 | d2 | digital io | General purpose GPIO | 3.3V |
| D3 | d3 | digital io | General purpose GPIO, PWM capable | 3.3V |
| D4 | d4 | digital io | General purpose GPIO, PWM capable | 3.3V |
| D5 | d5 | digital io | General purpose GPIO, PWM capable | 3.3V |
| D6 | d6 | digital io | General purpose GPIO, PWM capable | 3.3V |
| D7 | d7 | digital io | General purpose GPIO, PWM capable | 3.3V |
| D8 | d8 | digital io | General purpose GPIO, PWM capable | 3.3V |
| D9 | d9 | digital io | General purpose GPIO, PWM capable | 3.3V |
| D10 | d10 | digital io | General purpose GPIO | 3.3V |
| D11 | d11 | digital io | General purpose GPIO, PWM capable | 3.3V |
| D12 | d12 | digital io | General purpose GPIO | 3.3V |
| D13 | d13 | digital io | General purpose GPIO, PWM capable, connected to red LED (L) | 3.3V |
| D0/RX | d0 | digital io | GPIO #0, Serial1 RX (hardware UART), not used by USB-Serial so free to use | 3.3V |
| D1/TX | d1 | digital io | GPIO #1, Serial1 TX (hardware UART), not used by USB-Serial so free to use | 3.3V |
| D14/TX3 | d14 | digital io | GPIO #14, SERCOM5 TX (Mega-compat) | 3.3V |
| D15/RX3 | d15 | digital io | GPIO #15, SERCOM5 RX (Mega-compat), also I2S MCK | 3.3V |
| D16/TX2 | d16 | digital io | GPIO #16, SERCOM1 TX (Mega-compat) | 3.3V |
| D17/RX2 | d17 | digital io | GPIO #17, SERCOM1 RX (Mega-compat) | 3.3V |
| D18/TX1 | d18 | digital io | GPIO #18, SERCOM4 TX (Mega-compat) | 3.3V |
| D19/RX1 | d19 | digital io | GPIO #19, SERCOM4 RX (Mega-compat) | 3.3V |
| D20/SDA | d20 | digital io | GPIO #20, I2C data (same as top SDA) | 3.3V |
| D21/SCL | d21 | digital io | GPIO #21, I2C clock (same as top SCL, original Mega had separate I2C) | 3.3V |
| A0 | a0 | analog | ADC input + DAC0 (true analog output, 0-3.3V, independent of A1) | 3.3V |
| A1 | a1 | analog | ADC input + DAC1 (true analog output, 0-3.3V, independent of A0, PWM capable) | 3.3V |
| A2 | a2 | analog | ADC input + GPIO, 12-bit native resolution, PWM capable | 3.3V |
| A3 | a3 | analog | ADC input + GPIO, 12-bit native resolution | 3.3V |
| A4 | a4 | analog | ADC input + GPIO, 12-bit native resolution | 3.3V |
| A5 | a5 | analog | ADC input + GPIO, 12-bit native resolution | 3.3V |
| A6 | a6 | analog | ADC input + GPIO, 12-bit native resolution | 3.3V |
| A7 | a7 | analog | ADC input + GPIO, 12-bit native resolution | 3.3V |
| A8 | a8 | analog | ADC input + GPIO, 12-bit native resolution | 3.3V |
| A9 | a9 | analog | ADC input + GPIO, 12-bit native resolution | 3.3V |
| A10 | a10 | analog | ADC input + GPIO, 12-bit native resolution | 3.3V |
| A11 | a11 | analog | ADC input + GPIO, 12-bit native resolution | 3.3V |
| A12 | a12 | analog | ADC input + GPIO, 12-bit native resolution, PWM capable | 3.3V |
| A13 | a13 | analog | ADC input + GPIO, 12-bit native resolution | 3.3V |
| A14 | a14 | analog | ADC input + GPIO, 12-bit native resolution | 3.3V |
| A15 | a15 | analog | ADC input + GPIO, 12-bit native resolution, PWM capable | 3.3V |
| SCK | sck | digital io | Hardware SPI clock (2x3 header), shared with D52, keep free for high-speed SPI | 3.3V |
| MOSI | mosi | digital io | Hardware SPI MOSI (2x3 header), shared with D51, keep free for high-speed SPI | 3.3V |
| MISO | miso | digital io | Hardware SPI MISO (2x3 header), shared with D50, keep free for high-speed SPI | 3.3V |
| 5V (middle) | 5v-middle | power | 5V output (not 3.3V) | 5V |
| D22 | d22 | digital io | General purpose GPIO | 3.3V |
| D23 | d23 | digital io | General purpose GPIO | 3.3V |
| D24 | d24 | digital io | General purpose GPIO | 3.3V |
| D25 | d25 | digital io | General purpose GPIO | 3.3V |
| D26 | d26 | digital io | General purpose GPIO, also PCC DEN1 (camera) | 3.3V |
| D27 | d27 | digital io | General purpose GPIO, also PCC DEN2 (camera) | 3.3V |
| D28 | d28 | digital io | General purpose GPIO, also PCC CLK (camera) | 3.3V |
| D29 | d29 | digital io | General purpose GPIO, also PCC XCLK (camera) | 3.3V |
| D30 | d30 | digital io | General purpose GPIO, also PCC D7 (camera) | 3.3V |
| D31 | d31 | digital io | General purpose GPIO, also PCC D6 (camera), I2S DI | 3.3V |
| D32 | d32 | digital io | General purpose GPIO, also PCC D5 (camera), I2S DO | 3.3V |
| D33 | d33 | digital io | General purpose GPIO, also PCC D4 (camera), I2S FS | 3.3V |
| D34 | d34 | digital io | General purpose GPIO, also PCC D3 (camera) | 3.3V |
| D35 | d35 | digital io | General purpose GPIO, also PCC D2 (camera) | 3.3V |
| D36 | d36 | digital io | General purpose GPIO, also PCC D1 (camera) | 3.3V |
| D37 | d37 | digital io | General purpose GPIO, also PCC D0 (camera) | 3.3V |
| D38 | d38 | digital io | General purpose GPIO, also PCC D9 (camera) | 3.3V |
| D39 | d39 | digital io | General purpose GPIO, also PCC D8 (camera) | 3.3V |
| D40 | d40 | digital io | General purpose GPIO, also PCC D11 (camera) | 3.3V |
| D41 | d41 | digital io | General purpose GPIO, also PCC D10 (camera) | 3.3V |
| D42 | d42 | digital io | General purpose GPIO, also PCC D13 (camera) | 3.3V |
| D43 | d43 | digital io | General purpose GPIO, also PCC D12 (camera) | 3.3V |
| D44 | d44 | digital io | General purpose GPIO | 3.3V |
| D45 | d45 | digital io | General purpose GPIO, PWM capable | 3.3V |
| D46 | d46 | digital io | General purpose GPIO | 3.3V |
| D47 | d47 | digital io | General purpose GPIO | 3.3V |
| D48 | d48 | digital io | General purpose GPIO, PWM capable | 3.3V |
| D49 | d49 | digital io | General purpose GPIO | 3.3V |
| D50/MISO | d50 | digital io | GPIO, shared with middle SPI header MISO | 3.3V |
| D51/MOSI | d51 | digital io | GPIO, shared with middle SPI header MOSI | 3.3V |
| D52/SCK | d52 | digital io | GPIO, shared with middle SPI header SCK | 3.3V |
| D53/SS | d53 | digital io | GPIO, legacy Mega SPI secondary-select | 3.3V |
| PCC DEN1 | d26 | digital input | Parallel capture camera data enable 1 (fixed mapping to D26) | 3.3V |
| PCC DEN2 | d27 | digital input | Parallel capture camera data enable 2 (fixed mapping to D27) | 3.3V |
| PCC CLK | d28 | digital input | Parallel capture camera clock (fixed mapping to D28) | 3.3V |
| PCC XCLK | d29 | digital input | Parallel capture camera external clock (fixed mapping to D29) | 3.3V |
| PCC D0 | d37 | digital input | Parallel capture camera data bit 0 (fixed mapping to D37) | 3.3V |
| PCC D1 | d36 | digital input | Parallel capture camera data bit 1 (fixed mapping to D36) | 3.3V |
| PCC D2 | d35 | digital input | Parallel capture camera data bit 2 (fixed mapping to D35) | 3.3V |
| PCC D3 | d34 | digital input | Parallel capture camera data bit 3 (fixed mapping to D34) | 3.3V |
| PCC D4 | d33 | digital input | Parallel capture camera data bit 4 (fixed mapping to D33) | 3.3V |
| PCC D5 | d32 | digital input | Parallel capture camera data bit 5 (fixed mapping to D32) | 3.3V |
| PCC D6 | d31 | digital input | Parallel capture camera data bit 6 (fixed mapping to D31) | 3.3V |
| PCC D7 | d30 | digital input | Parallel capture camera data bit 7 (fixed mapping to D30) | 3.3V |
| PCC D8 | d39 | digital input | Parallel capture camera data bit 8 (fixed mapping to D39) | 3.3V |
| PCC D9 | d38 | digital input | Parallel capture camera data bit 9 (fixed mapping to D38) | 3.3V |
| PCC D10 | d41 | digital input | Parallel capture camera data bit 10 (fixed mapping to D41) | 3.3V |
| PCC D11 | d40 | digital input | Parallel capture camera data bit 11 (fixed mapping to D40) | 3.3V |
| PCC D12 | d43 | digital input | Parallel capture camera data bit 12 (fixed mapping to D43) | 3.3V |
| PCC D13 | d42 | digital input | Parallel capture camera data bit 13 (fixed mapping to D42) | 3.3V |
| I2S MCK | d15 | digital io | I2S master clock (fixed mapping to D15) | 3.3V |
| I2S FS | d33 | digital io | I2S frame sync (fixed mapping to D33) | 3.3V |
| I2S SCK | d14 | digital io | I2S serial clock (fixed mapping to D14) | 3.3V |
| I2S DO | d32 | digital output | I2S data out (fixed mapping to D32) | 3.3V |
| I2S DI | d31 | digital input | I2S data in (fixed mapping to D31) | 3.3V |
| QSPI Flash | qspi | other | 8 MB QSPI flash, 6 dedicated pins (4x data lines), not accessible on GPIO headers | 3.3V |
| NeoPixel | neopixel | led | Single RGB LED (pin 88 Arduino / board.NEOPIXEL CircuitPython), used for bootloader/CircuitPython status | 3.3V |
| Micro SD | sd | other | Micro SD card slot on dedicated SPI port (SPI1 in Arduino) | 3.3V |
| RESET | reset | reset | Reset button, double-tap to enter UF2 bootloader | 3.3V |
USB · 3.3 V
Confirm the data interface matches your host board.
Module pins: USB, DC Jack, Vin, 5V, 3V, 5V (middle), GND, TX. Schematik maps them to your board in the app.
Specialists: Teensy for high-clock audio and USB, Adafruit SAMD boards running CircuitPython or the Arduino IDE, proper STM32 eval kits, and the micro:bit classroom ecosystem. Schematik builds target ESP32, Arduino Uno, and Pico; come here when you have a specific reason to.
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