S. Marsanne

STMod+ Connector

Discussion created by S. Marsanne Employee on Jan 4, 2017
Latest reply on Apr 11, 2017 by S. Marsanne

A 2x10 pin, 2mm pitch header, carrying 3.3V signals and a +5V typical supply (USB or battery)



Some coming STM32 boards will offer this STMod+ connector. A "Fan-Out" board will be provided to enable its use :


Developers will get access to a broad selection of add-on HW modules types from the retail market.


As a bonus, users with soldering skills will be able to populate the missing headers depending on the needs:


For example, let's say we'd like to use one of these bread-boards:



The main difference between both of them is on the horizontal supply vias shifted locations.


Solder the right male pin headers on the back side of the Fan-Out board, then plug it firmly onto your breadboard. No jumper wires needed and ready to make something new.



And to make life a little bit easier, Fan-Out board comes with a built-in 3.3V @150mA regulation and a simple 3.3V to 5V I2C level shifter footprint.


The signals on the connector can be used to connect with various small form factor modules such as:


or or


Generally, besides I2C Bus signals, STMod+ signals are different than Arduino Uno's which enables Shield coexistence with an ESP-01, Click Boards , or Seeed Grove, while stacking more than a single Arduino Shield may cause HW conflict rework.


STM32 Boards with STMod+ connector


STM32F723E-DISCO Quick Reference Pinout, Handy and Printable Table:


STM32L496GDISCOVERY Quick Reference Pinout, Handy and Printable Table:



STM32L4R9I-DISCO Quick Reference Pinout Handy and Printable Table:

Preliminary Table  32L4R9IDISCOVERY




STMod+ Add-on Extensions

General note about STMod+ add-on module extensions:

1- Should have its own voltage regulation from +5V rail

==> To avoid the STM32 board voltage regulator overstress

==> To allow the add-on module decide the most power efficient regulating method (linear, DC-DC)

==> The add-on module can have its own power source (USD or else)

2- Should have its own signal level shifting mecanism to 3.3V

==> To make the add-on generic and swappable with others

==> Bi-directional shifters acts as protection agains shorts (mimic serial resistor)

3- When I2C lines are available, add an I2C EEPROM such as M24128DWMN

==> I2C Polling regularly for the EEPROM slave address acknowledge enable plug-unplug event

==> Using the OTP page in the EEPROM to store the Name of the Add-on for auto-detection (ASCII)


Available add-on modules:


P-L496G-CELL01  - STM32L496 2G/3G Cellular to Cloud Discovery Pack

Quick Reference Pinout (add-on board side) vs. STM32L496 Discovery as base board



P-L496G-CELL02- STM32L496G LTE Cat M1/NB1/2G Cellular to Cloud Discovery Pack

Quick Reference Pinout (add-on board side) vs. STM32L496 Discovery as base board


Tech details for cellular add-on board:

- Micro USB connector used to beef up 5V and upgrade the modem's software

- Modem signals going to STMod+ connector are level shifted (and protected) through level shifter bi-dir buffers

- 2 STMod+ signals (simselect 0:1) used to select (mux) MicroSIM or soldered embedded SIM configuration