MicroMod Weather Carrier Board Hookup Guide

Contributors: El Duderino, MAKIN-STUFF
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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 request 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