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Open Source Pmod Designs

August 23, 2020 - sam210723

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 Manufacturer FPGA Price Buy
iCESugar MuseLab Lattice ICE40UP5K $35 USD MuseLab AliExpress Store
Mimas V2 Numato Lab Xilinx XC6SLX9 $50 USD Numato Lab Store
iCEBreaker 1BitSquared Lattice iCE40UP5K $65 USD 1BitSquared Store
ULX3S Radiona Lattice LFE5U-12F / LFE5U-85F $115 / $155 USD Radiona Crowd Supply Store
ECPIX-5 LambdaConcept Lattice LFE5U-45F / LFE5U-85F €99 / €149 LambdaConcept Store
Arty A7 Digilent Xilinx XC7A35T / XC7A100T $129 / $249 USD Digilent Store


SFP Pmod

Interface for Small Form-factor Pluggable (SFP) modules


Interface for the TOSLINK fibre optic connector

Raspberry Pi Pico Pmod Adaptor

Connect Pmods to a Raspberry Pi Pico microcontroller

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.


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 Active high output indicating optical power level is below receiver threshold.
FLT Transmitter Fault Active high output indicating low optical output at the transmitter.
Toggling DIS will reset the transmitter to recover from the fault condition.
DIS Transmitter Disable Enable the transmitter by pulling this pin LOW.
If left floating or HIGH the transmitter will be disabled.
DET Module Detect Pulled low by the SFP module after successful startup
SDA Serial Data Data line of two-wire diagnostic and monitoring (MOD_DEF) interface
SCL Serial Clock Clock line of two-wire diagnostic and monitoring (MOD_DEF) interface
VCC Supply Power supply from host board (3.3V DC)
GND Ground Common ground with host board. The SFP cage is also connected to ground.

Manufacturer / Model Nominal Data Rate Wavelength Lowest Stable Rate
(50% duty cycle)
Cisco GLC-SX-MM 1.25 Gbps (1000BASE-SX 1GbE) 850 nm 50 kHz
Finisar FTLF8524P2BNL 1.062, 1.25, 2.125, 4.25 Gbps 850 nm 50 kHz
Cisco Compatible GLC-FE-100FX 125 Mbps (100BASE-FX 100MbE) 850 nm N/A

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.