Adafruit Grand Central M4

• Quick overview
• Connections
  • Switches
    • Analog inputs
  • Rotary encoders
  • Potentiometers
  • FSRs
  • PWM outputs
  • Traffic indicators
  • I2C
  • DIN MIDI
  • Touchscreen
  • Bootloader switch
• Flashing

Quick overview

• OpenDeck target name: grand_central_m4
• Power: Micro USB or 6-12V via barrel jack
• MCU: ATSAMD51P20A
• MIDI: USB, DIN
• OSC: No
• Traffic indicators: 2
• Digital inputs: 20
• Outputs: 20 (PWM / level control)
• Analog inputs: 16
• Board docs: Adafruit Grand Central M4 Express
• Buy links:
  • Adafruit

Connections

Pinout to use as an reference to pins in later sections:

Switches

Switch #	Pin 1	Pin 2
0	PC16	GND
1	PC17	GND
2	PC20	GND
3	PC21	GND
4	PD20	GND
5	PD21	GND
6	PB18	GND
7	PB22	GND
8	PB0	GND
9	PA17	GND
10	PA18	GND
11	PA19	GND
12	PA22	GND
13	PA23	GND
14	PC4	GND
15	PC5	GND
16	PC6	GND
17	PC7	GND
18	PC10	GND
19	PC11	GND

Analog inputs

Switch #	Pin 1	Pin 1	Pin 2
20	PA2	GND with 10k resistor	3V
21	PA5	GND with 10k resistor	3V
22	PB3	GND with 10k resistor	3V
23	PC0	GND with 10k resistor	3V
24	PC1	GND with 10k resistor	3V
25	PC2	GND with 10k resistor	3V
26	PC3	GND with 10k resistor	3V
27	PB4	GND with 10k resistor	3V
28	PB5	GND with 10k resistor	3V
29	PB6	GND with 10k resistor	3V
30	PB7	GND with 10k resistor	3V
31	PB8	GND with 10k resistor	3V
32	PB9	GND with 10k resistor	3V
33	PA4	GND with 10k resistor	3V
34	PA6	GND with 10k resistor	3V
35	PA7	GND with 10k resistor	3V

Rotary encoders

Encoder #	Pin 1	Pin 2	Pin 3
0	PC16	GND	PC17
1	PC20	GND	PC21
2	PD20	GND	PD21
3	PB18	GND	PB22
4	PB0	GND	PA17
5	PA18	GND	PA19
6	PA22	GND	PA23
7	PC4	GND	PC5
8	PC6	GND	PC7
9	PC10	GND	PC11

Potentiometers

Potentiometer #	Pin 1	Pin 2	Pin 3
0	3V	PA2	GND
1	3V	PA5	GND
2	3V	PB3	GND
3	3V	PC0	GND
4	3V	PC1	GND
5	3V	PC2	GND
6	3V	PC3	GND
7	3V	PB4	GND
8	3V	PB5	GND
9	3V	PB6	GND
10	3V	PB7	GND
11	3V	PB8	GND
12	3V	PB9	GND
13	3V	PA4	GND
14	3V	PA6	GND
15	3V	PA7	GND

FSRs

FSR #	Pin 1	Pin 2	Pin 2
0	3V	PA2	GND with 1k resistor
1	3V	PA5	GND with 1k resistor
2	3V	PB3	GND with 1k resistor
3	3V	PC0	GND with 1k resistor
4	3V	PC1	GND with 1k resistor
5	3V	PC2	GND with 1k resistor
6	3V	PC3	GND with 1k resistor
7	3V	PB4	GND with 1k resistor
8	3V	PB5	GND with 1k resistor
9	3V	PB6	GND with 1k resistor
10	3V	PB7	GND with 1k resistor
11	3V	PB8	GND with 1k resistor
12	3V	PB9	GND with 1k resistor
13	3V	PA4	GND with 1k resistor
14	3V	PA6	GND with 1k resistor
15	3V	PA7	GND with 1k resistor

PWM outputs

Note: current-limiting resistors for LEDs are required in order to avoid damage to the board.

Output #	Anode	Cathode
0	PB16	GND
1	PB17	GND
2	PC22	GND
3	PC23	GND
4	PB12	GND
5	PB13	GND
6	PD12	GND
7	PA15	GND
8	PC18	GND
9	PC19	GND
10	PA12	GND
11	PA13	GND
12	PA14	GND
13	PB19	GND
14	PB2	GND
15	PA16	GND
16	PA20	GND
17	PA21	GND
18	PB14	GND
19	PB15	GND

Traffic indicators

Indicator	LED
USB input	RX LED / PC31
USB output	TX LED / PC30
DIN input	RX LED / PC31
DIN output	TX LED / PC30

I2C

Signal	Pin
Vcc	3V
GND	GND
SDA	PB20
SCL	PB21

DIN MIDI

This board doesn't have DIN MIDI connectors, so they have to be added to the board with the corresponding circuitry. Use this schematic:

MIDI In	MIDI out
PB25	PB24

Touchscreen

Screen	Pin
Vcc	5V
GND	GND
Rx	PC13
Tx	PC12

Bootloader switch

Hold OpenDeck switch 0 / PC16 low while resetting or powering the board to enter the OpenDeck bootloader.

Flashing

To flash this board with the OpenDeck firmware, go to the OpenDeck configurator and follow the instructions.