MicroMod Weather Carrier Board Hookup Guide

Contributors: El Duderino, MAKIN-STUFF
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Introducing the MicroMod Weather Carrier Board! This nifty little weather station board works with all SparkFun MicroMod Processors so you can customize your weather station project to fit your needs.

SparkFun MicroMod Weather Carrier Board

SparkFun MicroMod Weather Carrier Board


The Weather Carrier Board includes three sensors: the BME280 Temperature, Pressure and Humidity sensor, the VEML6075 UV light sensor and the AS3935 lightning detector. Along with these on-board sensors there is a 3-pin latch terminal to add an external soil moisture sensor as well as a pair of RJ11 jacks to plug in the wind and rain sensors included with our Weather Meter Kit. To top it all off there is a microSD card slot so you can plug in an SD card to log all of that glorious weather data!

Required Materials

Like all of our MicroMod Carrier Boards, there is no processor included but instead you can plug in a processor of your choice to the MicroMod M.2 connector on the carrier. Here are few options to choose for your processor:

SparkFun MicroMod ESP32 Processor

SparkFun MicroMod ESP32 Processor

SparkFun MicroMod nRF52840 Processor

SparkFun MicroMod nRF52840 Processor

SparkFun MicroMod SAMD51 Processor

SparkFun MicroMod SAMD51 Processor

SparkFun MicroMod Artemis Processor

SparkFun MicroMod Artemis Processor


You'll also need a USB-C cable to connect the Carrier Board to your computer and if you want to add some Qwiic breakouts to your MicroMod project you'll want at least one Qwiic cable to connect it all together. Below are some options for both of those cables:

SparkFun Qwiic Cable Kit

SparkFun Qwiic Cable Kit

Flexible Qwiic Cable - 100mm

Flexible Qwiic Cable - 100mm

USB 3.1 Cable A to C - 3 Foot

USB 3.1 Cable A to C - 3 Foot

Reversible USB A to C Cable - 2m

Reversible USB A to C Cable - 2m


If you want to take full advantage of the features of the Weather Carrier Board you will also need a SparkFun Soil Moisture Sensor, the Weather Meter Kit and a microSD card:

Weather Meter Kit

Weather Meter Kit

microSD Card - 16GB (Class 10)

microSD Card - 16GB (Class 10)

SparkFun Soil Moisture Sensor (with Screw Terminals)

SparkFun Soil Moisture Sensor (with Screw Terminals)

SparkFun Soil Moisture Sensor

SparkFun Soil Moisture Sensor


Suggested Reading

The SparkFun MicroMod ecosystem offers a unique way to allow users to customize their project to their needs. Do you want to send your weather data via a wireless signal (e.g. Bluetooth or WiFi)? There's a MicroMod Processor for that. Looking to instead maximize efficiency and processing power? You guessed it, there's a MicroMod Processor for that.

If you aren't familiar with the MicroMod ecosystem, we recommend reading here for an overview.

MicroMod Logo

Before you get started with the Weather Carrier Board, you may want to read through the Hookup Guide for your chosen MicroMod Processor. MicroMod Processor Hookup Guides can be found on the processors' product pages. We also recommend reading through the following tutorials if you are not familiar with the concepts covered in them:

Serial Peripheral Interface (SPI)

SPI is commonly used to connect microcontrollers to peripherals such as sensors, shift registers, and SD cards.


An introduction to I2C, one of the main embedded communications protocols in use today.

Serial Terminal Basics

This tutorial will show you how to communicate with your serial devices using a variety of terminal emulator applications.

Getting Started with MicroMod

Dive into the world of MicroMod - a compact interface to connect a microcontroller to various peripherals via the M.2 Connector!

If you're interested in learning more about each of the sensors included on the Weather Carrier Board, take a look at their dedicated Hookup Guides:

Qwiic UV Sensor (VEML6075) Hookup Guide

Learn how to connect your VEML6075 UV Sensor and figure out just when you should put some sunscreen on.

SparkFun AS3935 Lightning Detector Hookup Guide (v20)

Are you worried about the looming clouds in the distance, how far away is that storm exactly? Add lightning detection with the AS3935 to your next weather station or your next bike ride!

Qwiic Atmospheric Sensor (BME280) Hookup Guide

Measure temperature, humidity, barometric pressure with the SparkFun Atmospheric Sensor Breakout BME280 (Qwiic).

Hardware Overview

In this section we'll cover the various hardware, sensors and adjustable solder jumpers on the MicroMod Weather Carrier Board, the external sensor connections and the pinout of the Carrier Board for a detailed look at how it connects to your chosen MicroMod Processor.

Common Components

Most SparkFun MicroMod Carrier Boards will have some common components and all MicroMod Carrier Boards will have the keyed M.2 MicroMod Connector to plug your processor into. The photo and list below outline some of the components you can expect on the Weather Carrier Board and most other SparkFun MicroMod Carrier Boards.

  • M.2 MicroMod Connector - This special keyed M.2 connector lets you install your MicroMod Processor of choice on your Weather Carrier Board.
  • USB-C Connector - Connect to your computer to program your processor and also can provide power to your MicroMod system.
  • 3.3V Regulator - Provides a regulated 3.3V and sources up to 1A.
  • Qwiic Connector - The standard Qwiic connector so you can add other Qwiic devices to your MicroMod system.
  • Boot/Reset Buttons - Push buttons to enter boot mode on processors and to reset your MicroMod circuit.
  • RTC Backup Battery & Charge Circuit - 1mAh backup battery for the Real-Time Clocks on MicroMod Processors that have a built-in RTC. Receives charge voltage from 3.3V.
  • microSD Slot - Insert a microSD card formatted to FAT32 here to log your weather data.

Annotated photo for common components on the Weather Carrier Board.

Weather Station Sensors and External Sensor Connections

As we mentioned in the introduction, the board comes with a BME280 Temperature, Pressure and Humidity Sensor, a VEML6075 UV Light Sensor and a AS3935 Lightning Detector. Along with those on board sensors there is a three pin latch terminal for a soil moisture sensor as well as a pair of RJ11 jacks for connecting wind and rain meters.

The three on board sensors paired with the external sensors allows for a powerful and customizable weather tracking tool.

BME280 Temperature, Pressure and Humidity Sensor

The BME280 Atmospheric Sensor from Bosch is the heavy lifter of the Weather Carrier Board. The BME280 is a highly-accurate, digital environmental sensor that measures ambient temperature, relative humidity and barometric pressure.

Weather Carrier Board with BME280 Highlighted.

The BME280 measures humidity from 0 to 100% with an absolute accuracy of ±3 %RH (from 20-80%RH), temperatures between 0°C to 65°C with an absolute accuracy of ±0.5-1.5°C (full temperature range is -40°C to 85°C) and atmospheric pressures between 300 to 1100hPa with an absolute accuracy of ±1hPa (relative accuracy of ±0.12hPa). The I2C address of the BME280 is 0x77.

For detailed information on the sensor's functionality and characteristics, refer to the BME280 Datasheet or our Hookup Guide for the SparkFun Qwiic Atmospheric Sensor (BME280).

VEML6075 UV Sensor

The VEML6075 UV light sensor from Vishay Semiconductors measures UVA (320-400 nm, peak @365 ±10nm ) and UVB (228-320 nm, peak @330 ±10nm) irradiance so you can calculate the UV Index at your Weather Station. Example 4 - Calculate UVI in the SparkFun VEML6075 Arduino Library demonstrates how to calculate that index using this sensor.

Weather Carrier Board with VEML6075 Highlighted.

The VEML6075 has a UVA resolution of 0.93 counts/µW/cm2 and a UVB resolution of 2.1 counts/µW/cm2. The I2C address is 0x10.

For more information about this UV sensor, refer to the VEML6075 datasheet or our Hookup Guide for the SparkFun Qwiic UV Sensor (VEML6075).

AS3935 Lightning Detector

The AS3935 Lightning Detector from AMS can detect lightning strikes up to 40km away with an accuracy of up to 1km from the storm front. The specially-tuned antenna picks up lightning events in the 500kHz band and a built-in algorithm helps check the incoming signal pattern to reject potential man-made disturbers such as DC/DC converters in large appliances.

Weather Carrier Board with AS3935 and Antenna Highlighted.

The AS3935 Lightning Detector is connected to the primary SPI bus and Chip Select (CS) for the AS3935 is tied to G1/Bus1 (MicroMod pad 42).

For in-depth information about the sensor, refer to the AS3935 Datasheet or our Hookup Guide for the SparkFun Lightning Detector Breakout.

Soil Moisture Sensor Latch Terminal

The three-pin latch terminal makes it easy to connect a Soil Moisture Sensor to your Weather Carrier Board. The soil moisture sensor is a handy addition to the Weather Carrier Board if you are using it in something like a greenhouse environment to keep an eye on your soil and, with some slick coding, you could even turn an irrigation system on or off depending on the sensor's measurements.

Weather Carrier Board with Soil Moisture Latch Terminal Highlighted.

The Soil Moisture Sensor has two large coated pads that act as prongs for what is essentially a large variable resistor. The sensor takes advantage of a simple concept of moist soil being more conductive than dry soil so as more water is added to the soil, the resistance of the circuit drops and the SIG output increases.

Power (3.3V) for the sensor is provided by G0 (MicroMod pad 40) allowing you to turn it on and off easily (continuous power is not recommended for the soil moisture sensor) and the Signal output is tied to A0 (MicroMod pad 34).

If you are looking for some inspiration for an automated watering project, check out our Product Showcase Video and the Soil Moisture Sensor Hookup Guide.

Wind and Rain RJ11 Connectors

The two RJ11 connectors allow you to connect the wind and rain sensors included with our Weather Meters Kit to monitor wind speed, wind direction and rainfall. These two sensors are great additions to an outdoor Weather Carrier Board setup to get a more complete view of weather in the area.

Weather Carrier Board with Wind and Rain RJ11 Jacks Highlighted.

The Weather Meters Kit includes an anemometer to measure wind speed, a wind vain to determine wind direction and a self-emptying tipping bucket collector to monitor rainfall. The anemometer outputs a digital signal tied to D0 (MicroMod pad 10). The wind vain outputs an analog signal relative to its position tied to A1 (MicroMod pad 38). The rainfall detector outputs a digital signal to D1 (MicroMod pad 18).

For help assembling and testing your Weather Meters Kit, check out our Weather Meter Hookup Guide.

Plated Through-Hole Headers

The Weather Carrier Board also routes several pins from a connected MicroMod Processor to a pair of plated through-hole (PTH) headers.

Weather Carrier Board with PTH Headers highlighted

On the "North"/Top of the board, the primary SPI bus is routed to a PTH header (the CS pin on this header is routed to G2/BUS2), a trio of Ground pins and both PWM1 & PWM0 if users wish to solder components that can use pulse-width modulation.

The "South"/Bottom of the board features both Serial UARTs (UART1 & UART2), another pair of Ground pins as well as 3.3V and SDA/SCL from the primary I2C bus if users prefer to have a soldered connection for I2C devices instead of the Qwiic connector.

Solder Jumpers

If you have never worked with solder jumpers and PCB traces before or would like a quick refresher, check out our How to Work with Solder Jumpers and PCB Traces tutorial for detailed instructions and tips.

There are a total of seven adjustable solder jumpers on the MicroMod Weather Carrier Board labeled I2C, MEAS, BYP, VE, UV, 5V and 3V3. The table below briefly outlines their functionalities:

Jumper Name/Label Description Default State
I2C Pull-Up/I2C Pulls the SDA/SCL lines to 3.3V via two 2.2K Ohm resistors CLOSED
Measure/MEAS Open this jumper to probe the current draw at the 3.3V output of the regulator. For help measuring current, take a look at our How to Use a Multimeter tutorial. CLOSED
Bypass/BYP The "penny-in-the-fuse" jumper. Bypasses the 6V/2A fuse and nets VIN and V_USB together. Close only if you know what you are doing! OPEN
Voltage Regulator Enable/VE Voltage regulator control. Close this jumper to control the VREG in low-power applications. OPEN
UV Sensor Power/UV Connects VDD of the VEML6075 UV Sensor to 3.3V. Open the jumper to disable power to the UV Sensor. CLOSED
VIN LED Power/VIN LED Connects the 5V/VIN LED to 5V via a 1K Ohm resistor. Open to disable the LED. CLOSED
3.3V LED Power/3V3 LED Connects the 3.3V LED to 3.3V via a 1K Ohm resistor. Open to disable the LED. CLOSED
Highlighting the solder jumpers on the front of the Data Logging Carrier Board Highlighting the solder jumpers on the back of the Data Logging Carrier Board

Having trouble viewing the detail in these photos? Click on them for a larger view.

MicroMod Pinout

Since this carrier board is designed to work with all of the MicroMod Processors we've included the table below to outline which pins are used so, if you would like, you can compare them to the pinout tables in their respective Hookup Guides.

M.2 Connector Pin# MicroMod Pin Name Weather Station Connection Description
1 GND GND Ground plane.
2 3.3V 3.3V Regulated 3.3V via USB-C.
3 USB_D+ Passthrough USB D+ connection for Processor Board.
4 3.3V_EN 3.3V Enable Voltage regulator enable input.
5 USB_D- Passthrough USB D- connection for Processor Board.
6 RESET RESET Button Connected to RESET Button. Reset is active LOW
9 USB_VIN VIN Input voltage from USB.
10 D0 WSPEED Digital pin for wind speed.
11 BOOT BOOT Button Connected to BOOT Button. Boot is active LOW.
12 I2C_SDA I2C_SDA I2C data signal for BME280, VEML6075 and other Qwiic/I2C devices.
14 I2C_SCL I2C_SCL I2C clock signal for BME280, VEML6075 and other Qwiic/I2C devices.
17 UART_TX1 TX1 UART1 data output. Tied to TX1 PTH header pin.
18 D1/CAM_TRIG RAIN Digital pin for rain meter signal.
19 UART_RX1 RX1 UART1 data input. Tied to RX1 PTH header pin.
20 UART_RX2 RX2 UART2 data input. Tied to RX2 PTH header pin.
21 SWDCK SWDCK Serial Wire Debug Clock.
22 UART_TX2 TX2 UART2 data output. Tied to TX2 PTH header pin.
23 SWDIO SWDIO Serial Wire Debug I/O
32 PWM0 PWM0 Dedicated PWM0 pin. Broken out to PTH header pin.
34 A0 SOIL_MOIST_SIG Analog input from soil mositure sensor.
38 A1 WDIR Analog input for wind direction.
40 G0/BUS0 SOIL_MOIST_PWR General purpose pin configured for 3.3V output.
42 G1/BUS1 LIGHTNING_CS AS3935 Chip Select.
44 G2/BUS2 HEADER_CS General chip select pin. Tied to SPI PTH header.
46 G3/BUS3 LIGHTNING_INT AS3935 interrupt pin.
47 PWM1 PWM1 Dedicated PWM1 pin. Broken out to PTH header pin.
49 BATT_VIN/3 VIN/3 Divided input voltage for monitoring power supply.
55 SPI_CS SD_CS µSD Chip Select.
57 SPI_SCK SPI_SCK SPI clock signal.
59 SPI_COPI SPI_COPI SPI Controller Out/Peripheral In signal.
61 SPI_CIPO SPI_CIPO SPI Controller In/Peripheral Out signal.
72 RTC_3V RTC_3V 3V output for backup battery charging.
Function Bottom
(Not Connected) 75 GND
3.3V 74 73 G5 / BUS5
RTC_3V_BATT 72 71 G6 / BUS6
SPI_CS1# SDIO_DATA3 (I/O) 70 69 G7 / BUS7
SDIO_DATA2 (I/O) 68 67 G8
PDM_CLK PCM_CLK I2S_SCK AUD_BCLK 50 49 BATT_VIN / 3 (I - ADC) (0 to 3.3V)
G4 / BUS4 48 47 PWM1
G3 / BUS3 46 45 GND
G2 / BUS2 44 43 CAN_TX
G1 / BUS1 42 41 CAN_RX
G0 / BUS0 40 39 GND
A1 38 37 USBHOST_D-
A0 34 33 GND
PWM0 32 31 Module Key
Module Key 30 29 Module Key
Module Key 28 27 Module Key
Module Key 26 25 Module Key
Module Key 24 23 SWDIO
UART_TX2 (O) 22 21 SWDCK
UART_RX2 (I) 20 19 UART_RX1 (I)
CAM_TRIG D1 18 17 UART_TX1 (0)
I2C_INT# 16 15 UART_CTS1 (I)
I2C_SCL (I/0) 14 13 UART_RTS1 (O)
I2C_SDA (I/0) 12 11 BOOT (I - Open Drain)
D0 10 9 USB_VIN
SWO G11 8 7 GND
RESET# (I - Open Drain) 6 5 USB_D-
3.3V_EN 4 3 USB_D+
3.3V 2 1 GND
Signal Group Signal I/O Description Voltage
Power 3.3V I 3.3V Source 3.3V
GND Return current path 0V
USB_VIN I USB VIN compliant to USB 2.0 specification. Connect to pins on Processor Board that require 5V for USB functionality 4.8-5.2V
RTC_3V_BATT I 3V provided by external coin cell or mini battery. Max draw=100μA. Connect to pins maintaining an RTC during power loss. Can be left NC. 3V
3.3V_EN O Controls the carrier board's main voltage regulator. Voltage above 1V will enable 3.3V power path. 3.3V
BATT_VIN/3 I Carrier board raw voltage over 3. 1/3 resistor divider is implemented on carrier board. Amplify the analog signal as needed for full 0-3.3V range 3.3V
Reset Reset I Input to processor. Open drain with pullup on processor board. Pulling low resets processor. 3.3V
Boot I Input to processor. Open drain with pullup on processor board. Pulling low puts processor into special boot mode. Can be left NC. 3.3V
USB USB_D± I/O USB Data ±. Differential serial data interface compliant to USB 2.0 specification. If UART is required for programming, USB± must be routed to a USB-to-serial conversion IC on the processor board.
USB Host USBHOST_D± I/O For processors that support USB Host Mode. USB Data±. Differential serial data interface compliant to USB 2.0 specification. Can be left NC.
CAN CAN_RX I CAN Bus receive data. 3.3V
CAN_TX O CAN Bus transmit data. 3.3V
UART UART_RX1 I UART receive data. 3.3V
UART_TX1 O UART transmit data. 3.3V
UART_RTS1 O UART ready to send. 3.3V
UART_CTS1 I UART clear to send. 3.3V
UART_RX2 I 2nd UART receive data. 3.3V
UART_TX2 O 2nd UART transmit data. 3.3V
I2C I2C_SCL I/O I2C clock. Open drain with pullup on carrier board. 3.3V
I2C_SDA I/O I2C data. Open drain with pullup on carrier board 3.3V
I2C_INT# I Interrupt notification from carrier board to processor. Open drain with pullup on carrier board. Active LOW 3.3V
I2C_SCL1 I/O 2nd I2C clock. Open drain with pullup on carrier board. 3.3V
I2C_SDA1 I/O 2nd I2C data. Open drain with pullup on carrier board. 3.3V
SPI SPI_COPI O SPI Controller Output/Peripheral Input. 3.3V
SPI_CIPO I SPI Controller Input/Peripheral Output. 3.3V
SPI_SCK O SPI Clock. 3.3V
SPI_CS# O SPI Chip Select. Active LOW. Can be routed to GPIO if hardware CS is unused. 3.3V
SPI/SDIO SPI_SCK1/SDIO_CLK O 2nd SPI Clock. Secondary use is SDIO Clock. 3.3V
SPI_COPI1/SDIO_CMD I/O 2nd SPI Controller Output/Peripheral Input. Secondary use is SDIO command interface. 3.3V
SPI_CIPO1/SDIO_DATA0 I/O 2nd SPI Peripheral Input/Controller Output. Secondary use is SDIO data exchange bit 0. 3.3V
SDIO_DATA1 I/O SDIO data exchange bit 1. 3.3V
SDIO_DATA2 I/O SDIO data exchange bit 2. 3.3V
SPI_CS1/SDIO_DATA3 I/O 2nd SPI Chip Select. Secondary use is SDIO data exchange bit 3. 3.3V
Audio AUD_MCLK O Audio master clock. 3.3V
AUD_OUT/PCM_OUT/I2S_OUT/CAM_MCLK O Audio data output. PCM synchronous data output. I2S serial data out. Camera master clock. 3.3V
AUD_IN/PCM_IN/I2S_IN/CAM_PCLK I Audio data input. PCM syncrhonous data input. I2S serial data in. Camera periphperal clock. 3.3V
AUD_LRCLK/PCM_SYNC/I2S_WS/PDM_DATA I/O Audio left/right clock. PCM syncrhonous data SYNC. I2S word select. PDM data. 3.3V
AUD_BCLK/PCM_CLK/I2S_CLK/PDM_CLK O Audio bit clock. PCM clock. I2S continuous serial clock. PDM clock. 3.3V
SWD SWDIO I/O Serial Wire Debug I/O. Connect if processor board supports SWD. Can be left NC. 3.3V
SWDCK I Serial Wire Debug clock. Connect if processor board supports SWD. Can be left NC. 3.3V
ADC A0 I Analog to digital converter 0. Amplify the analog signal as needed to enable full 0-3.3V range. 3.3V
A1 I Analog to digital converter 1. Amplify the analog signal as needed to enable full 0-3.3V range. 3.3V
PWM PWM0 O Pulse width modulated output 0. 3.3V
PWM1 O Pulse width modulated output 1. 3.3V
Digital D0 I/O General digital input/output pin. 3.3V
D1/CAM_TRIG I/O General digital input/output pin. Camera trigger. 3.3V
General/Bus G0/BUS0 I/O General purpose pins. Any unused processor pins should be assigned to Gx with ADC + PWM capable pins given priority (0, 1, 2, etc.) positions. The intent is to guarantee PWM, ADC and Digital Pin functionality on respective ADC/PWM/Digital pins. Gx pins do not guarantee ADC/PWM function. Alternative use is pins can support a fast read/write 8-bit or 4-bit wide bus. 3.3V
G1/BUS1 I/O 3.3V
G2/BUS2 I/O 3.3V
G3/BUS3 I/O 3.3V
G4/BUS4 I/O 3.3V
G5/BUS5 I/O 3.3V
G6/BUS6 I/O 3.3V
G7/BUS7 I/O 3.3V
G8 I/O General purpose pin 3.3V
G9/ADC_D-/CAM_HSYNC I/O Differential ADC input if available. Camera horizontal sync. 3.3V
G10/ADC_D+/CAM_VSYNC I/O Differential ADC input if available. Camera vertical sync. 3.3V
G11/SWO I/O General purpose pin. Serial Wire Output 3.3V

Board Dimensions

The Weather Carrier Board measures 2.65" x 2.30" (67.31mm x 58.42mm) and has four mounting holes that fit a standard 4-40 screw.

MicroMod Weather Carrier Board Dimensions

Hardware Assembly

Now that we are familiar with the hardware and sensors on the Weather Carrier Board, it's time to assemble it with your chosen MicroMod Processor and get it connected to your computer.

Inserting your Processor

With the M.2 MicroMod connector, connecting your processor board is a breeze. Simply match up the key on your processor's beveled edge connector to the key on the M.2 connector. At a 45° angle, insert the processor board to the M.2 connector. The processor board will stick up at an angle as seen here:

nRF52840 Processor is inserted to M.2 connector on Weather Carrier board at 45 degree angle.

Once the board is in the socket, gently press the processor board down, grab the set screw and tighten it with a Phillip's head screwdriver:

Securing nRF52840 Processor into place with the MicroMod set screw and a screwdriver.

Once the processor board is secure, your assembled MicroMod system should look similar to the image below!

MicroMod nRF52840 Processor secured to the Weather Carrier Board.

Note: There is technically no way to insert the processor backward since the key prevents it from mating with the M.2 connector. As an extra safeguard to prevent inserting a processor improperly or with a poor connection, the mounting screw will not match up if the processor is not plugged in entirely.

Assembling External Sensors

For users with the Soil Moisture Sensor and/or the Weather Meters Kit some extra assembly is required. We have detailed assembly instructions for both of these peripherals in their respective Hookup Guides. You can find them here:

Soil Moisture Sensor Hookup Guide

A quick hookup guide and project to get you started with the Soil Moisture Sensor from SparkFun.

Weather Meter Hookup Guide

How to assemble your very own weather meter!

Once your external sensors are assembled, connecting them is a snap (literally). To connect the Soil Moisture Sensor, simply plug in the three wires to the three-pin latch terminals taking care to match the signals. For the Weather Meters, just plug the connectors for the Wind & Rain signals into their matching RJ11 jacks on the Weather Carrier Board.

Connecting Everything Up

With your processor inserted and secured it's time to connect your MicroMod Weather Carrier Board to your computer using the USB-C connector. Depending on which processor you choose and which drivers you already have installed, you may need to install drivers for your board. Refer to your processor's hookup guide for detailed instructions on how to install them.

Fully assembled MicroMod Weather Carrier Board with external sensors

With your MicroMod Weather Carrier Board, Processor Board, and any external sensors assembled we can now move on to uploading some code to monitor your environment! Head on to the next section for an example to test all the sensors the Weather Carrier Board features.

Weather Station Arduino Example

Note:These examples assume you are using the latest version of the Arduino IDE on your desktop. If this is your first time using Arduino, please review our tutorial on installing the Arduino IDE. If you have not previously installed an Arduino library, please check out our installation guide.

We've written a few examples to get started with the Weather Carrier Board. They can be found in the "Examples" folder of Hardware GitHub Repository and will work with any SparkFun MicroMod Processor you choose. In this section we'll only cover the comprehensive Weather Station example, but you can use the other examples to test each sensor on the Weather Carrier along with the additional soil moisture and weather meter sensors.

Note: Make sure that for whichever MicroMod Processor you choose, you have the correct board definitions installed.

For this particular example, we are using the Artemis MicroMod Processor. Board definitions for this processor board can be found in the Software Setup and Programming section of the Artemis MicroMod Processor Board Hookup Guide.

If you are using a different processor, go to our MicroMod Processor Boards landing page, find your Processor, and head on over to its tutorial for help installing your board definition.

MicroMod Weather Carrier Board Test Example

Before getting started with the Weather Carrier Board Example you will need to install the Board Definitions for your chosen MicroMod Processor (outlined above) as well as the BME280, VEML6075 and AS3935 Arduino Libraries. You can install them using the Arduino Library manager and searching 'SparkFun BME280', 'SparkFun VEML6075' and 'SparkFun AS3935'. Alternatively, you can download the libraries from their respective GitHub repositories linked above or you can download the .ZIP for each of them by clicking the buttons below:

With the libraries and processor board definitions installed we can go ahead and move on to opening the MicroMod Weather Example sketch and uploading it to our MicroMod Processor. You can open a new blank sketch and copy the code from below or you can download the entire GitHub repository for the Weather Carrier Board which includes all of the examples by clicking the button below:

Navigate to the location the repository downloaded to and open the Examples folder. In that folder you'll find examples for each sensor as well as MM_Weather_CB_Test. Open that example in the Arduino IDE or copy the code below into a blank sketch, select your Board and Port and click "Upload".

 * MicroMod Weather Carrier Board Example
 * This sketch tests all of the weather sensors on the carrier board:
 * atmospheric sensor - BME280, UV sensor - VEML6075, lightning detector - AS3935,
 * soil moisture sensor, wind and rain meters.
 * Priyanka Makin @ SparkX Labs
 * Original Creation Date: August 20, 2020
 * This code is Lemonadeware; if you see me (or any other SparkFun employee) at the
 * local, and you've found our code helpful, please buy us a round!
 * Hardware Connections:
 * Insert MicroMod Processor Board of your choice into the M.2 connector of the SparkFun Weather carrier
 *  Screw into place
 * Connect Weather carrier board to power useing USB-C cable
 * Connect SparkFun Soil Moisture Sensor to Weather carrier using latching terminals
 * Connect both wind and rain meters to Weather carrier using the RJ11 connectors

#include <Wire.h>
#include <SPI.h>
#include "SparkFunBME280.h"
#include <SparkFun_VEML6075_Arduino_Library.h>
#include "SparkFun_AS3935.h"

BME280 tempSensor;
VEML6075 uv;
SparkFun_AS3935 lightning;

#define INDOOR 0x12 
#define OUTDOOR 0xE
#define LIGHTNING_INT 0x08
#define DISTURBER_INT 0x04
#define NOISE_INT 0x01

#if defined(ESP_PLATFORM)
int LED_BUILTIN = 5;
//int A0 = 34;
int G0 = 4;
int D0 = 23;
//int A1 = 35;
int D1 = 27;
const int G3 = 17;
int G1 = 12;
#elif defined(ARDUINO_ARCH_SAMD)
int G0 = 2;
int D0 = 0;
int D1 = 1;
//const int lightningInt = G3;  //SPI does not currently work on the SAMD51 proto
//int spiCS = G1;

int soilPin = A0;  //Pin number that measures analog moisture signal
int soilPower = G0;  //Pin number that will power the soil moisture sensor
int WSPEED = D0; //Digital I/O pin for wind speed
int WDIR = A1; //Analog pin for wind direction
int RAIN = D1;   //Digital I/O pin for rain fall
const int lightningInt = G3; // Interrupt pin for lightning detection
int spiCS = G1; //SPI chip select pin

volatile bool rainFlag = false;
volatile bool windFlag = false;

//Function is called every time the rain bucket tips
void rainIRQ()
  rainFlag = true;

//Function is called when the magnet in the anemometer is activated
void wspeedIRQ()
  windFlag = true;

// This variable holds the number representing the lightning or non-lightning
// event issued by the lightning detector. 
int intVal = 0;
int noise = 2; // Value between 1-7 
int disturber = 2; // Value between 1-10

void setup() {
  while (!Serial);

  Serial.println("MicroMod Weather Carrier Board Test");


  if (tempSensor.beginI2C() == false) { //Begin communication over I2C
    Serial.println("BME280 did not respond.");
    while(1); //Freeze
  if (uv.begin() == false) {
    Serial.println("VEML6075 did not respond.");

  pinMode(soilPower, OUTPUT);
  digitalWrite(soilPower, LOW);
  // When lightning is detected the interrupt pin goes HIGH.
  pinMode(lightningInt, INPUT);

  //Initialization for weather meter
  pinMode(WSPEED, INPUT_PULLUP);  //Input from wind meters windspeed sensor
  pinMode(RAIN, INPUT_PULLUP);    //Input from wind meters rain gauge sensor
  //attach external interrupt pins to IRQ functions
  attachInterrupt(digitalPinToInterrupt(RAIN), rainIRQ, FALLING);
  attachInterrupt(digitalPinToInterrupt(WSPEED), wspeedIRQ, FALLING);
  //turn on interrupts

  if(lightning.beginSPI(spiCS, 2000000) == false){ 
    Serial.println ("Lightning Detector did not start up, freezing!"); 
    Serial.println("Schmow-ZoW, Lightning Detector Ready!");

  // The lightning detector defaults to an indoor setting at 
  // the cost of less sensitivity, if you plan on using this outdoors 
  // uncomment the following line:

// the loop function runs over and over again forever
void loop() {
  digitalWrite(LED_BUILTIN, HIGH);   // turn the LED on (HIGH is the voltage level)

  Serial.print("Temperature: ");
  Serial.println(tempSensor.readTempF(), 2);
  Serial.print("Humidity: ");
  Serial.println(tempSensor.readFloatHumidity(), 0);
  Serial.print("Pressure: ");
  Serial.println(tempSensor.readFloatPressure(), 0);
  Serial.print("Altitude: ");
  Serial.println(tempSensor.readFloatAltitudeFeet(), 1);

  Serial.print("UV A, B, index: ");
  Serial.println(String(uv.uva()) + ", " + String(uv.uvb()) + ", "+ String(uv.index()));

  Serial.print("Soil Moisture = ");

  Serial.print("Wind direction: ");
  Serial.println(" degrees");
  //Check interrupt flags
  if (rainFlag == true){
    Serial.println("Rain click!");
    rainFlag = false;
  if (windFlag == true){
    Serial.println("Wind click!");
    windFlag = false;

  // Hardware has alerted us to an event, now we read the interrupt register
  if(digitalRead(lightningInt) == HIGH){
    intVal = lightning.readInterruptReg();
    if(intVal == NOISE_INT){
      // Too much noise? Uncomment the code below, a higher number means better
      // noise rejection.
    else if(intVal == DISTURBER_INT){
      // Too many disturbers? Uncomment the code below, a higher number means better
      // disturber rejection.
    else if(intVal == LIGHTNING_INT){
      Serial.println("Lightning Strike Detected!"); 
      // Lightning! Now how far away is it? Distance estimation takes into
      // account any previously seen events in the last 15 seconds. 
      byte distance = lightning.distanceToStorm(); 
      Serial.print("Approximately: "); 
      Serial.println("km away!"); 

  digitalWrite(LED_BUILTIN, LOW);    // turn the LED off by making the voltage LOW


int readSoil() {
  int moistVal = 0;  //Variable for storing moisture value
  //Power Senor
  digitalWrite(soilPower, HIGH);
  moistVal = analogRead(soilPin);  //Read the SIG value from sensor
  digitalWrite(soilPower, LOW); //Turn the sensor off
  return moistVal; //Return current moisture value

int getWindDirection()
  unsigned int adc;
  adc = analogRead(WDIR); //get the current readings from the sensor

  if (adc < 380) return (113);
  if (adc < 393) return (68);
  if (adc < 414) return (90);
  if (adc < 456) return (158);
  if (adc < 508) return (135);
  if (adc < 551) return (203);
  if (adc < 615) return (180);
  if (adc < 680) return (23);
  if (adc < 746) return (45);
  if (adc < 801) return (248);
  if (adc < 833) return (225);
  if (adc < 878) return (338);
  if (adc < 913) return (0);
  if (adc < 940) return (293);
  if (adc < 967) return (315);
  if (adc < 990) return (270);
  return (-1);

The code begins by checking which MicroMod Processor was selected in Arduino and adjusts a few pin settings accordingly so it will work with any SparkFun MicroMod Processor. Next, it initializes all the on board sensors and checks for proper responses as well as checking for external sensors (wind, rain and soil).

Once all the sensors initialize, the code prints out data from each sensor. Open your serial monitor and set the baud to 115200 to watch the data print out.

Resources and Going Further

For more information about the MicroMod Weather Carrier Board, check out the following links:

For more information about the SparkFun MicroMod Ecosystem, take a look at the links below:

Looking for some project inspiration using your Weather Station Carrier? The tutorials below can help you get started!

Si4707 Hookup Guide

Instructions on hooking up to and communicating with the Si4707 Weather Band Radio Breakout using an Arduino.

Photon Remote Water Level Sensor

Learn how to build a remote water level sensor for a water storage tank and how to automate a pump based off the readings!

micro:climate Kit Experiment Guide

A weather station kit that is built on top of the inexpensive, easy-to-use micro:bit and Microsoft MakeCode.

SparkFun gator:soil Hookup Guide

The gator:soil is analog soil moisture sensor. This tutorial will get you started using the gator:soil with the micro:bit platform.