LinkSprite pcDuino3 Nano

The LinkSprite pcDuino v3 Nano is an A20 development board with Arduino-compatible headers.

= Identification =

A white, credit-card-sized PCB with an A20 chip. "PCDUINO_NANO" is marked on the board to the right of the A20.

= Sunxi support =

Current status
The pcDuino3 Nano is supported by the mainline U-Boot and kernel; it's not supported by the legacy sunxi U-Boot or kernel.

Images
The Ubuntu 14 image that LinkSprite provides uses a modified linux-sunxi 3.4 kernel. Their patches and build scripts are available on GitHub.

The most important modification is in the GMAC driver, to set the GMAC_TX_DELAY parameter to 3. This adjusts the relative timing of the clock and data signals to the PHY in order to compensate for differing trace lengths on the PCB (details; the Banana Pi has the same problem). Without this modification, the Ethernet port will work at 100Mbit but not at 1000Mbit. Upstream U-Boot now sets this parameter itself, so the kernel patch isn't needed any more (patch).

Mainline U-Boot
For building mainline u-boot, use the Linksprite_pcDuino3_Nano target. (Patch should be merged in U-Boot v2015.04.)

Mainline kernel
Use the sun7i-a20-pcduino3-nano.dtb device-tree file for the mainline kernel. (Patch should be merged in Linux 3.21.)

= Tips, Tricks, Caveats =

FEL mode
The "UBOOT" button triggers FEL mode.

= Adding a serial port =



Locating the UARTs
The pcDuino3 Nano provides access to two of the A20's UARTs. See the UART howto for more details.

The 3-pin header labelled "UART" sticking out from the side of the board is the A20's UART0. Pin 1 (with a square pad, closest to the IR receiver) is RX, pin 2 is ground, pin 3 is TX.

UART2 is available on the Arduino-style J11 connector. Pin 1 (closest to the Ethernet socket) is RX, and pin 2 is TX. Ground is available on pin 7 of J8.

Note that the labelling in LinkSprite's diagram is a bit confusing -- UART2 is described from the A20's point of view but UART0 from the serial cable's point of view, i.e. RX and TX are reversed for UART0.

= Pictures =

= Also known as =

This device has not been rebadged.

= See also =


 * LinkSprite pcDuino
 * LinkSprite pcDuino V2
 * LinkSprite pcDuino V3
 * Diagram of pcDuino v3 Nano connectors and header pinouts
 * LinkSprite's pcDuino kernel repository on GitHub
 * pcDuino3 Nano ubuntu and android images