Milk-V · Single-board computer

Milk-V Duo (CV1800B)

A five dollar board that boots Linux on a RISC-V core, in the Raspberry Pi Pico footprint. USB-C at the top, pin 1 top-left.

Cheat sheet (SVG)

Logic level: 3.3 V GPIO, 1.8 V ADC
Package: 2x20 castellated / 2.54 mm, 21 x 51 mm

1.Pinout diagram

Highlight a signalhover to preview, click to keep

Pins 1-20

MILK-V DUO

Pins 21-40

Pin detail

Hover a pin for its mappings and gotchas. Click to keep it here.

Logic level: 3.3 V GPIO, 1.8 V ADC
Package: 2x20 castellated / 2.54 mm, 21 x 51 mm

Fig. 1. Milk-V Duo (CV1800B), 2x20 castellated. Hover or tap a signal to light up every pin that carries it.

2.Watch out

The ADC pins are 1.8 V, not 3.3 V. GP26 and GP27 will be damaged by a 3.3 V signal. This is the sharpest edge on the board and it is easy to miss because every other pin is 3.3 V.
It is the Pico footprint but not a Pico drop-in. Pins 34 and 35 are unpopulated where a Pico has GP28 and ADC_VREF, and the peripheral mapping behind every GP number is completely different.
GP16 to GP21 are the SPI NOR and NAND flash lines. Boot from microSD and leave the flash unused and you get them back; otherwise they are spoken for.
There is 100 Mbps Ethernet on five pads along the bottom edge: TX+, TX-, GND, RX+, RX-. They need an external magnetics module or an RJ45 jack with magnetics built in.
The serial console is UART0 on GP12 and GP13 at 3.3 V. With no display output, that console is how you talk to the board before networking comes up.
It boots from microSD. There is no on-board eMMC on the base Duo, so the card is not optional.
The CV1800B pairs a 1 GHz C906 RISC-V core with a 700 MHz one and a small 8051, and there is a camera socket on board. The later Duo 256M and Duo S use the SG2002 and change both the memory and some pin functions.
GPIO numbers in sysfs are the XGPIO and PWR_GPIO values listed per pin, not the GP number on the silkscreen. GP0 is 508, not 0.

3.Full pin reference

Every pin, alias and mapping. This is the table that prints.

Table 1. Pin assignments.

Complete pin reference for Milk-V Duo (CV1800B)
Pin	Name	Also called	Functions	Notes
1	GP0I²CUART	XGPIOA[28], 508	I2C0 SCL, UART1/2 TX, JTAG TDI
2	GP1I²CUART	XGPIOA[29], 509	I2C0 SDA, UART1/2 RX, JTAG TDO
3	GND	-	Ground
4	GP2PWMUART	PWR_GPIO[26], 378	PWM10, UART4 TX, SD1 GP1
5	GP3PWMUART	PWR_GPIO[25], 377	PWM11, UART4 RX, SD1 GP0
6	GP4PWMI²CUART	PWR_GPIO[19], 371	PWM5, I2C1 SCL, UART2/3 TX, SD1 D2
7	GP5PWMI²CUART	PWR_GPIO[20], 372	PWM6, I2C1 SDA, UART2/3 RX, SD1 D1
8	GND	-	Ground
9	GP6SPIPWMI²CClock	PWR_GPIO[23], 375	SPI2 SCK, PWM9, I2C3 SDA, SD1 CLK
10	GP7SPIPWMI²C	PWR_GPIO[22], 374	SPI2 SDO, PWM8, I2C3 SCL, SD1 CMD
11	GP8SPIPWMI²C	PWR_GPIO[21], 373	SPI2 SDI, PWM7, I2C1 SDA, SD1 D0
12	GP9SPIPWMI²C	PWR_GPIO[18], 370	SPI2 CS, PWM4, I2C1 SCL, SD1 D3
13	GND	-	Ground
14	GP10I²C	XGPIOC[9], 425	I2C1 SDA
15	GP11I²C	XGPIOC[10], 426	I2C1 SCL
16	GP12PWMUART	XGPIOA[16], 496	UART0/1 TX, PWM4, JTAG TMS	UART0 is the serial console by default, at 3.3 V.
17	GP13PWMUART	XGPIOA[17], 497	UART0/1 RX, PWM5, JTAG TCK	The other half of the console.
18	GND	-	Ground
19	GP14	XGPIOA[14], 494	GPIO
20	GP15	XGPIOA[15], 495	GPIO
21	GP16SPI	XGPIOA[23], 503	SPI NOR MISO, SPI NAND MISO	Wired to the on-board SPI NOR / NAND flash. Free only if you boot from microSD and leave the flash alone.
22	GP17SPI	XGPIOA[24], 504	SPI NOR CS, SPI NAND CS	Wired to the on-board SPI NOR / NAND flash. Free only if you boot from microSD and leave the flash alone.
23	GND	-	Ground
24	GP18SPIClock	XGPIOA[22], 502	SPI NOR SCK, SPI NAND SCK	Wired to the on-board SPI NOR / NAND flash. Free only if you boot from microSD and leave the flash alone.
25	GP19SPI	XGPIOA[25], 505	SPI NOR MOSI, SPI NAND MOSI	Wired to the on-board SPI NOR / NAND flash. Free only if you boot from microSD and leave the flash alone.
26	GP20	XGPIOA[27], 507	SPI NOR WP, SPI NAND WP	Wired to the on-board SPI NOR / NAND flash. Free only if you boot from microSD and leave the flash alone.
27	GP21	XGPIOA[26], 506	SPI NOR HOLD, SPI NAND HOLD	Wired to the on-board SPI NOR / NAND flash. Free only if you boot from microSD and leave the flash alone.
28	GND	-	Ground
29	GP22	PWR_GPIO[4], 356	GPIO
30	RUN	RESET	Chip enable / reset	Pull low to reset, same position as the Pico's RUN pin.
31	GP26ADC	XGPIOB[3], 451, ADC1	ADC channel 1	1.8 V MAXIMUM, not 3.3 V. Feeding it a 3.3 V signal damages the input. Divide everything.
32	GP27ADC	XGPIOB[6], 454, ADC2	ADC channel 2	1.8 V MAXIMUM, not 3.3 V.
33	GND	-	Ground
34	NC	-	Not connected	Unpopulated. The Pico has GP28 here, which is why a Pico carrier does not map one to one.
35	NC	-	Not connected	Unpopulated. The Pico has ADC_VREF here.
36	3V3(OUT)3.3 V	-	3.3 V supply out
37	3V3_EN	-	Regulator enable	Pulled high on board. Pull low to shut the 3.3 V rail down.
38	GND	-	Ground
39	VSYS5 V	-	System supply in
40	VBUS5 V	-	USB bus voltage

Primary sources

Found a wrong pin? The whole board is one file, data/boards/milk-v-duo.json.

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