Version: Nano

Design:

This version is a size reduction over the Uno. It is significantly smaller, somewhat more power efficient and more flexible. This system is based around the Arduino Nano Micro Controller, which is essentially just a shrunk down version of the Uno. For this one, you need to physically add in the SD reader and RTC components (there are also some available data logger shields online for the Nano. They may be good, but I've never tested to see). This means more wiring / soldering and therefore more initial work. But it also means you have full control over what parts are used and the layout of the logger system.

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Parts:

1. Arduino Nano (or one of its many cheaper clones)

2. SD reader breakout board (there are tons of these. This is linking to one of the smaller / cheaper ones you can get on Amazon)

3. DS3231 RTC breakout board (Again, This is linking to a cheaper one I know works, but there are tons of these out there)

4. Optional Screw terminal board (This can help with keeping wiring clean / simple, but you don't need this. You can just solder everything directly to the Nano)

5. DC-DC converter / voltage regulator (optional if you want to control the voltage source to the board)

5. FAT 16 / 32 micro SD card, and whatever coin battery is needed to power your RTC module

6. Various colors of 22 awg wire (for soldering to the breakout boards)

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After this you will need whatever sensors you wish to use, along with some wiring to connect a power source (battery, wall, solar, etc).

 

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Assembly:

Before you begin wiring everything, you'll need to decide how big of a footprint you want this logger to have. The smallest footprint would be to solder everything directly to the Nano, using the shortest length of wire. This will end up looking messy, but will allow you to fit this into some pretty tight places (you could also connect everything through a prototyping board as well). If you'd like more flexibility with changing parts, I'd recommend using the Screw Terminal shield. This will allow you to change out parts if they fail, or if you want to change sensors, and it can be better for wire management. 

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If using the screw terminal; begin by soldering in the headers for the Nano (small metal pins). Then insert the Nano into the screw terminal board. 

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For the SD reader: Solder some length of wire to the following pins and connect to the Nano as follows - 

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​3v (or VCC) pin of SD - to - 3.3v pin of Nano*

Ground of SD - to - Ground of Nano

CLK of SD - to - pin 13 of Nano

DO (or MISO) of SD - to - pin 12 of Nano

DI (or MOSI) of SD - to - pin 11 of Nano

CS of SD - to - pin 10 of Nano

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For the RTC Module: Solder some length of wire to the following pins and connect to the Nano as follows -

 

​3v (or VCC) pin of RTC - to - 3.3v pin of Nano*

Ground of RTC - to - Ground of Nano

SCL of RTC - to - A5 of Nano

SDA of RTC - to - A4 of Nano

SQW of RTC - t0 - pin 2 of Nano

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Once everything is connected, you should be good to go. Just make sure you add in the micro SD card and appropriate coin battery for the RTC module. 

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*You'll notice that the SD and RTC modules both use the 3.3v pin (and ground pin) of the Nano. You will need to 'tie' these wires together somehow; either by soldering them together and then running a single wire to the Nano. Or, if using the screw terminal, you will need to twist the wires together before connecting to the terminal. Also; the RTC board is communicating via I2C. This is only important to know if you plan on using a sensor that is also working via I2C. If that is the case, you will need to tie the sensor and RTC module's I2C pins together. 

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Adding Sensors and Uploading Code:

To add sensors, simply follow the wiring diagrams / design provided by the manufacturer. Refer to the Sensors page of this site for further guidance in selecting sensors, and wiring them in to your DIY system. 

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For code, you can find some simple code for this system at the linked GitHub page. Under the "Version Nano" folder you will find a "Blank" code that is a generic logger code that works with this setup. Make sure to add in the additional code needed to power and record your sensors, and modify the timing interval. If that seems unclear, there are some example code of sensor systems built in the past also in that folder. Feel free to use these as guidance. If you are totally new to Arduino, I recommend reading / watching some of the many amazing online tutorials for getting started with connecting your Arduino and uploading code. Minimally, you'll need to download the Arduino IDE (code interface) and probably read through the "Getting Started" documentation. 

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​Arduino Nano Data Logger Specs:

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Internal Operating Voltage:  5 V

Digital output pins power: 5 V and up to 40 mA

Base Operating power consumption (with out anything running): 19 mA

Lower power sleep power consumption (average in my tests, with LED's removed): 5 -7 mA

Dimensions (Using the Screw Terminal and no components): 4.5 cm W x 5.5 cm L x 3 cm T

Dimensions (Without Screw Terminal and no components): 2 cm W x 4.5 cm L x 1 cm T

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A Note on Power:

​For all the system in this website, you will need to supply them with some sort of power. All the Arduino boards used here are 5v boards, which means that at a minimum they need a 5 v power source supplied. For optimal power efficiently (lowest current draw) I recommend suppling around  5-6v directly to the Arduino boards via their VCC / Vin pins. By doing this, you limit the need for the Arduino to lower the voltage coming in, which is a more efficient way to power the board. 

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If you wish to deploy these without any connection to land, I recommend using some rechargeable batteries that are 6- 12 v. Run those batteries through the DC-DC converter / external voltage regulator and set the incoming voltage to the Arduino to 5 - 6v. DigiKey is a great resource for finding various battery types. If you are running off of solar or some sort of 'land' power, then I still recommend going through a converter to regulate the voltage, but you won't have to be as concerned with power efficiency. One note though: many of the more inexpensive DC-DC converters will end up consuming more power by itself then the rest of the logger uses while in sleep mode. If you really need to stretch your system life, I recommend looking for efficient power converters, or feeding the power source directly to the Arduino. Just be aware that directly feeding a higher voltage source (6v or more) to the Arduino will cause the Arduino to generate heat. This may cause the system to overheat, especially if using sensors that pull a lot of power. 

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If you want to learn more about conserving power with regards to Arduinos, there is a really good blog post that runs through all the different coding and physical things that can be done to lower the power consumption of the boards, as well as some documentation from Arduino themselves.  For the designs on this site, the Arduinos are being put to low power sleep in-between measurements, and all LED's are removed from the boards.