Xpress demo board: stacking click boards


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Stacking SPI click boards

Well, that’s the big no-no. All the click boards using SPI communication need the CS pin, and that pin is the same position for all the click boards using SPI communication. So, one can use only one SPI click board in the stack.

The only way to use two SPI click boards is to place one click board in the mikroBUS socket and the second click board on a breadboard, routing the CS pin of the second click board to an unused microcontroller pin.

SPI and I2C click boards

As long as there are no pin conflicts, one can use one SPI click board and a stack of click boards that use I2C communication. As an example, the GSM2 click uses almost all pins but SDA and SCL – it can be used with an I2C click board that has no interrupt pins, such as the SHT1x Click. In the picture in this blog post you can see one of the possible I2C and SPI combinations: a thermometer/humidity meter made with one SHT1x click and OLED W click.

Serial communication boards

Only one board using serial communication can be used in a stack. It can be combined with SPI and I2C click boards as long as there are no conflicting pins.

As an example I would give the GSM3 click which uses the RX, TX pins plus AN, RST, PWM, CS – this click board can be combined with an I2C click board that uses only the SDA and SCL pins.

The WiFi3 click uses RX, TX, AN and RST pins, It will work fine for example with the Weather click to make an Internet-enabled weather station.

If you live in Europe, LoRa click uses RX, TX, RST and INT pins. It can also work fine with the Weather click. However, if you live in US, Canada, Australia or New Zealand you have to rely on the LoRa2 click, which uses RX, TX, RST, INT plus the CS pin. You can’t use it with SPI click boards, but it will work fine with the above weather click.

The 3.3V version of the RS-485 click uses only the RX and TX lines – it will work will almost all other click boards.


There are two relay click boards, one using the PWM and CS pins, the other using the AN and PWM pins. As long there are no pin conflicts you can use them in a stack – combine them with an SHT click to make a room thermostat, for example.

Motion sensor click

This one uses RST and INT pins. It can be combined with the relay click boards. You can combine the motion sensor with an RS-485 click in a motion controlled DMX lighting project.

Bottom line

Stacking click boards can provide a relatively easy way to expand the use of the MPLAB Xpress board, allowing us to create complex projects, while still keeping a low cost of implementation.

While I have written this post initially with the Xpress board in mind, there are other boards that can benefit from click stacking – everything from the Microchip Curiosity up to the MikroElektronika clicker boards or even the Arduino Uno plus Arduino Uno click shield.

There are over 200 click boards at this moment, so I can’t think of all possible combinations. In this blog post I gave some ideas on how to combine click boards, but I’m also curious to know what others have done. So, if you have a working project made by stacking click boards – please share it in the comments section.

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