Skip to main content

Interfaces

A DUELink module receives simple text commands over a physical bus — USB, I2C, or UART — and sends responses back the same way. The bus is the interface.

For example, sending StatLed(200,200,5) over the interface blinks the on-board STAT LED five times. Every module understands a common set of commands like this, plus its own module-specific ones — see Get Started for the full picture and each product's Commands tab for what it supports.

Any host that can write text can drive a module: a PC, Raspberry Pi, Arduino, micro:bit, phone, or another DUELink microcomputer.

Interfaces

Every module has two JST connectors — Uplink (white, marked U) and Downlink (blue, marked D) — that work together to let many modules be chained into a Daisylink.

The Uplink connector is the module's input port. It accepts commands from either a host or the previous module in a chain.

Arduino UNO with DUELink modules

Uplink supports all three buses — USB, I2C, and UART — through the same physical connector. The module detects which one is active on power-up (see Interface Detection below).

Microcomputer variants​

Some modules — the microcomputer form factor — replace the JST Uplink with a direct USB connector. These can only use the USB interface.

DueDuino

Modules with only a JST Uplink can still connect to a PC through a small adapter like USB Hook.

USB Hook with an RGB3 module

The Downlink connector is the module's output port for adding more modules. Plug the Uplink of the next module into the Downlink of the current one, and commands flow through.

Uplink to Downlink

The pattern is: host → Uplink of module 1 → Downlink of module 1 → Uplink of module 2 → Downlink of module 2 → ... Each module is a signal repeater along the way, and each one gets its own address (1, 2, 3, ...) assigned automatically on power-up. The host selects which module a command targets with Sel(n).

Downlink is handled automatically by the internal engine. For the full picture — addresses, broadcast, multi-select, and host mode — see Daisylink.

Daisylinked modules

Wireless​

The chain doesn't have to be physical — a wireless link can carry commands between segments of the same Daisylink.

Wireless daisylink

Interface Detection​

On power-up, a module checks its interface pins. If both are pulled high, it configures itself for I2C. Otherwise it watches for activity on USB or UART and selects whichever wakes first.

Connector safety​

Proper connection

See Connector Safety for how to handle JST connectors without damaging them.