Open Source Pmod Designs

Open Source Pmod Designs

The Pmod Standard developed by Digilent is a peripheral protocol, interconnect and form-factor guideline supported by various FPGA and microcontroller development boards. Digilent manufacture a wide variety of modules which conform to the Pmod standard. Some development boards which support the standard are listed below.

Board FPGA Price Purchase
MuseLab iCESugar Lattice ICE40UP5K $35 USD AliExpress
Numato Lab Mimas V2 Xilinx XC6SLX9 $50 USD Numato Lab
1BitSquared iCEBreaker Lattice iCE40UP5K $65 USD 1BitSquared
Radiona ULX3S Lattice LFE5U-12F / -85F $115 / $155 USD Crowd Supply
LambdaConcept ECPIX-5 Lattice LFE5U-45F / -85F €99 / €149 LambdaConcept
Digilent Arty A7 Xilinx XC7A35T / 100T $129 / $249 USD Digilent

Small Form-factor Pluggable (SFP) Pmod

Small Form-factor Pluggable (SFP) transceivers typically convert bi-directional electrical signalling to a pair of optical fibres for transmission over long distances. These modules are commonly found in telecommunications and networking applications where they carry various protocols including Ethernet and Fibre Channel.

Some SFP modules are capable of drawing over 100mA. The Pmod standard assumes a maximum current draw per Pmod of 100mA. Check your development board is capable of supplying the required current through the Pmod connectors before plugging in a SFP module.


The PCB is a 4-layer impedance controlled board which uses the JLC7628 stackup and JLCPCB design rules. Project files and gerbers were built with Autodesk EAGLE 9.6.2. A bill of materials is available on Octopart.


This module uses a single 12-pin 0.1" header to interface with the host board.

Pin Name Description
TXD Transmit Data Single-ended input to differential transmitter
RXD Receive Data Single-ended output of differential receiver
LOS Loss of Signal HIGH when optical power level is below receiver threshold.
FLT Transmitter Fault HIGH when optical output level at the transmitter is low.
DIS Transmitter Disable Transmitter is enabled when this pin is LOW.
DET Module Detect Pulled low by the SFP module after successful startup
SDA Serial Data Data line of two-wire MOD_DEF interface
SCL Serial Clock Clock line of two-wire MOD_DEF interface
VCC Supply Power supply from host board (3.3V DC)
GND Ground Digital ground (including SFP cage)

Toggling DIS will reset the transmitter to recover from a fault condition, as indicated by the FLT pin.

Further Reading

SFP Design Guide
SFP Diagnostic Monitoring Interface Specification

TOSLINK is a connector standard which is used to carry S/PDIF digital audio over an optical fibre. Transmitters are cheap as they use an LED instead of a laser to emit light into the fibre. This pair of Pmods use the Cliff OTJ-5 (RS 805-1680) and ORJ-5 (RS 805-1671) transmitter and receiver which are capable of up to 16 Mbps.


Raspberry Pi Pico Pmod Adaptor

The Raspberry Pi Pico is a development board based on the RP2040 microcontroller. This PCB design adds a Pmod compatible host connector to the Raspberry Pi Pico. The 3.3v regulator on the Raspberry Pi Pico can supply about 300mA which is sufficient for the 100mA limit specified in the Pmod Standard.