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Mini Pearl Logger
mini-pearl-logger

The Mini Pearl Logger is a powerful and inexpensive device for logging environmental data. It is based on an Arduino Pro Mini in combination with a real time clock and a microSD card reader. Combining these common electronic components allows logging data from multiple sensors for multiple months. Three different kits to build a Mini Pearl Logger are available at the [KAPtery](http://kaptery.com/products/data-and-control). The [Mini Pearl Logger Kit](http://kaptery.com/product/mini-pearl-logger-kit) is a minimal version that requires soldering and runs a sketch that puts the logger to sleep between logging events to conserve battery power. The [Mini Pearl Pro Logger Kit](http://kaptery.com/product/mini-pearl-pro-logger-kit) includes a TPL5110 low power timer which turns the logger off between logging events and maximizes battery life. The [Mini Pearl Snap Logger Kit](http://kaptery.com/product/mini-pearl-snap-logger-kit) includes a TPL5110 timer, a BMP280 sensor, an FTDI converter, and snaps together with no soldering required. [![FeatureTable.PNG](https://publiclab.org/system/images/photos/000/023/322/large/FeatureTable.PNG)](https://publiclab.org/system/images/photos/000/023/322/original/FeatureTable.PNG) All three kits include a DS3231 real-time clock which has an integrated temperature sensor and timekeeping is automatically corrected for temperature. Data from this sensor can be read and logged. The Mini Pearl Snap Logger Kit includes an additional external sensor for barometric pressure and temperature, and many other sensors (including I²C, 1 Wire, and Grove) can be connected to any Mini Pearl Logger. [![miniGo_20180107-2413.JPG](https://publiclab.org/system/images/photos/000/023/319/medium/miniGo_20180107-2413.JPG)](https://publiclab.org/system/images/photos/000/023/319/original/miniGo_20180107-2413.JPG) _Above: The parts included in the Mini Pearl Snap Logger Kit. Everything needed to log temperature and barometric pressure for many months (except three AA batteries) is included. An FTDI converter (red) for connecting the logger to your computer is also included._ This logger is based on Ed Mallon's [Cave Pearl Logger](https://edwardmallon.wordpress.com/2015/10/24/diy-arduino-logger-build-instructions-part-1/) which uses a similar combination of components. Ed has done extensive testing to extend the field longevity to more than a year. [![miniGo_20180107-2448.JPG](https://publiclab.org/system/images/photos/000/023/318/medium/miniGo_20180107-2448.JPG)](https://publiclab.org/system/images/photos/000/023/318/original/miniGo_20180107-2448.JPG) _Above: An assembled Mini Pearl Snap Logger. The six components are connected with DuPont wires which slide onto header pins on the PCBs. It takes about 15 minutes to get one finished and logging data._ ###Parts Primary components: - **Arduino Pro Mini**. Pro Minis are available on [eBay from sellers in Asia for under $2.00](https://www.ebay.com/sch/i.html?_from=R40&_sacat=0&_nkw=Arduino+Pro+Mini&rt=nc&LH_BIN=1). At US retailers prices are between $4.00 and $20.00. Pro Minis come in 3.3v and 5v versions, and the 3.3v version is required. - **Adafruit TPL5110 Low Power Timer**. Available from [Adafruit for $4.95](https://www.adafruit.com/product/3435). - **DS3231 real time clock**. This module is available on [eBay for about $1.20](https://www.ebay.com/itm/Top-1-2PCS-Arduino-DS3231-AT24C32-IIC-Module-Precision-Real-Time-Clock-Memory/182840998778?hash=item2a922c3b7a:m:mkMwmF_bfaCkRIqfFG3yeTw) or from [US retailers for $4.00 to $15.00](https://www.amazon.com/Diymore-DS3231-AT24C32-Precision-Arduino/dp/B01IXXACD0/ref=sr_1_5?s=electronics&ie=UTF8&qid=1513187359&sr=1-5&keywords=ds3231+real+time+clock+module). Some DS3231 chips do not work at temperatures below 0°C, but these are not included in KAPtery kits. - **3.3 volt MicroSD card socket**. These modules are available on [eBay for less than $1.00](https://www.ebay.com/sch/sis.html?_nkw=10pcs+Mini+SD+Card+Module+Memory+Module+Micro+SD+Card+Module+for+Arduino+AVR+ARM&_id=331907413969&&_trksid=p2057872.m2749.l2658). There are many different microSD card modules, and some are better at low sleep current. Also required: - **Battery or battery case** for AA or AAA. The Mini Pearl Logger is a 3.3 volt device. Three alkaline batteries (3 x 1.5v = 4.5v) are adequate or four NiMH (4 x 1.2v = 4.8v). LiPo or LiPoly batteries (3.7v) are also good. - **MicroSD card**. Cards of 1 GB or smaller capacity are best if the logger will be slept (instead of turned off with a timer) because they tend to sleep better and at lower current. - **CR2032 coin cell** battery for real time clock. ###Assembly There are documents with guidance about assembling and getting started with the Mini Pearl Loggers at the [KAPtery Guides page](http://kaptery.com/guides/). ###Software A different Arduino sketch for each version of the Mini Pearl Logger can be downloaded at the [KAPtery Guides page](http://kaptery.com/guides/). Below are some research notes about activities done with Mini Pearl Loggers. Some of these notes include the sketch which was used in the activity described. ## Activities [activities:mini-pearl-logger] ## Questions [questions:mini-pearl-logger] ...


Author Comment Last activity Moderation
cfastie "I have not heard of anyone using a microcontroller (Arduino or ESP board) to read data from an SD card. But maybe it is possible. A more common str..." | Read more » almost 3 years ago
amir_hudsonconsulting "My goal is to log data to an SD card, and store the data locally on the SD card. Is it possible to connect a mobile device via Bluetooth and read t..." | Read more » almost 3 years ago
yp1080030 "CLICK HERE " | Read more » almost 3 years ago
cfastie "I haven't tried that Feather combination. I have also never seen a list of Feather-Featherwing combinations that are incompatible. So I assume it w..." | Read more » almost 3 years ago
amir_hudsonconsulting "Hi I'm wondering does anyone know if you can stack the Adafruit Feather M0 Bluefruit LE with the Adalogger featherwing? My reason for wanting to do..." | Read more » almost 3 years ago
cfastie "It looks like the PIC12LF will do what you need. There is also a low power 555 timer (TLC555) but it is not as low power as the PIC12LF. " | Read more » almost 3 years ago
tcpipchip "cfastie First of all, many thanks about your answer! And time to answer! You said "But if the microcontroller can send a DONE signal as soon as the..." | Read more » almost 3 years ago
cfastie "The TPL5110 depends on getting a signal to the DONE pin, so I am not sure it can just send a pulse every eight seconds. The TPL5111 sets an enable ..." | Read more » almost 3 years ago
tcpipchip "Hi, excelent post! Is there some config without use of DONE gpio, that make the DRV make a pulse each 8 seconds ? I want to send a pulse to a gpi..." | Read more » almost 3 years ago
cfastie "Low power operation: To run your data logger for a long time on small batteries, you can put the Arduino and other components to sleep between log..." | Read more » over 3 years ago
pdhixenbaugh "@cfastie I have 6 weeks (weekends) to get this set up and running for the lake at my summer camp. I don't have the low power timer, but I am going ..." | Read more » over 3 years ago
cfastie " The link was finally fixed on May 16, 2019 when the view count was 1005. " | Read more » over 3 years ago
marsh_jasonh " Oh, that's awesome - That gives me the info I was looking for, thank you very much, really helpful! " | Read more » over 3 years ago
cfastie "The specs for the TPL-5110 timer IC say it can time intervals up to 7200 seconds (2 hours). It seems unlikely that it could be extended beyond that..." | Read more » over 3 years ago
marsh_jasonh " Obviously kind of an old article, but I am just getting into arduino and electronics in general. My question is I have a similar project to this ..." | Read more » over 3 years ago
cfastie "Thanks, I have pinged the editor. The views on this research note have doubled since December. I wonder what they would be if the link had been co..." | Read more » over 3 years ago
warren " Indeed, that's cool! Thanks! I did notice their link seems broken though - did you want to reach out to the editor? It links to: https://makezi..." | Read more » over 3 years ago
cfastie " I just noticed that Limor Fried wrote an article for Make Magazine in January citing this research note and using one of the images. An editor ask..." | Read more » over 3 years ago
liz "This is so useful! Another imaginative concept brought to real world utility by Chris Fastie. If I ever have a well, I will install this to learn a..." | Read more » about 4 years ago
warren "Tremendous! :tada: " | Read more » about 4 years ago
MadTinker "Just a quick update on the status of this project. Willow Creek is going through a couple of serious events. First, the stretch of the stream where..." | Read more » over 4 years ago
MadTinker "@cfastie FWIW I used a Kalman filter algorithm for my TDS analyses with data from a similar setup data logger setup. I believe that my original im..." | Read more » over 4 years ago
cfastie "What do you guys think, is it okay to use the mean instead of the median? @pdhixenbaugh, @MadTinker, @Shanlter, @rockets " | Read more » over 4 years ago
hpprinter1995 "Nice And Informative Website. Please Keep Continue Such Kind Of Effort. Contact Us And Get On-Site HP Printer Support & HP Scanner Support. Our..." | Read more » over 4 years ago