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The Digilent Pmod LED has four red LEDs controlled individually through GPIO, but it does not plug directly into an Arduino Uno R3: the Uno has no six-pin Pmod socket. Before connecting them, identify the Pmod’s pin order, provide its recommended 3.3 V supply rather than assuming the Uno’s 5 V rail is suitable, and use a cable or adapter whose connector gender and pin order match your hardware.

What the Pmod LED does

The Digilent Pmod LED is a four-channel indicator board. Its four high-brightness red LEDs are transistor-driven, so each LED is controlled by a GPIO signal; Digilent specifies a required driving current below 1 mA. The board uses a six-pin connector and complies with the Type 1 Pmod interface. See the Digilent Pmod LED product page.

Pmod LED pinout and recommended supply

Pin numbers matter: the connector carries four LED control signals, ground, and supply. Digilent’s PmodLED Reference Manual recommends operating the module at 3.3 V.

Pmod pin Connection Purpose
1 LD0 Controls LED 0
2 LD1 Controls LED 1
3 LD2 Controls LED 2
4 LD3 Controls LED 3
5 GND Ground
6 VCC Power input; recommended operation is 3.3 V

Use the manual’s pin numbering and the orientation marking on the actual board or cable to identify pin 1. Do not infer pin order from how a loose connector happens to face.

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Why the Uno needs a cable or adapter

The Arduino Uno R3 is a 5 V board with digital GPIO and separate power pins, but it does not have a native six-pin Pmod connector. The Uno documentation lists a recommended operating current of 20 mA per I/O pin and a maximum current of 50 mA for its 3.3 V pin; these are different specifications and neither establishes compatibility for every Pmod wiring arrangement. Consult the Arduino Uno R3 documentation.

Digilent’s Pmod guide discusses six-pin MTE cables and header or gender-changer accessories. Which accessory works depends on the Uno headers, cable, and adapter at hand. Confirm connector gender and, crucially, that each conductor lands on the intended numbered Pmod pin.

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Plan the electrical connection before wiring

Treat supply and signal connections as separate decisions. The Pmod LED manual recommends 3.3 V at VCC; do not casually connect that pin to the Uno’s 5 V rail. The Uno’s GPIO is in a 5 V board context, while the cited Pmod material does not establish the electrical protection or level translation provided by every cable or adapter. Check the electrical characteristics of the exact hardware combination before driving the Pmod control inputs from Uno GPIO.

  • Identify Pmod pins 1–6 using the manual and the board’s orientation marking.
  • Check that the adapter routes the four signal pins, ground, and supply to the corresponding positions rather than relying on connector fit alone.
  • Verify how the Pmod receives its recommended 3.3 V supply and whether the particular setup safely handles the Uno’s GPIO signal levels.
  • Do not treat a microcontroller damage limit as a target operating current; use the Uno’s documented recommended per-pin current when assessing GPIO loads.

The available product and board documentation establishes the Pmod pinout, the recommended supply, and general Uno specifications, but not one universal Uno-to-Pmod wiring recipe for every revision and accessory. A precise pin-to-pin hookup should therefore be based on the actual adapter’s wiring and confirmed electrical behavior, not just the connector shape.

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When to choose a different Pmod

If four red indicators are enough, the Pmod LED’s six-pin Type 1 interface is the relevant option. If the project needs eight indicators, Digilent’s Pmod 8LD provides eight green LEDs and a 2×6 GPIO connector. It has a different connector and interface arrangement, so it is not a drop-in replacement for the four-LED Pmod LED.

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  • [Ultra-Compact Size] Measuring just 23 x 18 mm, the Tang Primer 25K SOM board is perfect for space-constrained projects. When used with the expansion dock (64 x 40 mm), it provides easy access to 75 general-purpose I/O pins, a 2x20-pin 2.54 mm header for SDRAM modules, and three Pmod connectors for HDMI, PS2, or other expansion modules.
  • [On-Board Debugging] Tang Primer 25K dock board integrates a high-speed USB-JTAG debugger and supports UART communication via a single USB-C port, eliminating the need for an external programmer. This streamlines the development workflow, ensuring fast code uploads and debugging.
  • [Versatile Interfaces] Tang Primer 25K dock board includes a USB-A host port (USB 1.1) for connecting game controllers or HID devices, two onboard buttons, and full pin access (excluding the MIPI high-speed lanes). It is ideal for retro gaming projects, university lab courses, and open-source hardware experiments.
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