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A minimal library for binary data logging in ESP8266 systems
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bitmario/SPIFFSLogger
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A minimal library for binary data logging in ESP8266 systems.
- Easy to use
- Stores data in binary along with a UTC timestamp
- Results in about 50% space spavings when compared to logging the same data in CSV
- Splits data into daily files, allowing for efficient search
- Automatically rotates files, deleting the ones that exceed the specified age
- Uses built-in ESP/newlib time functions
- Download thelatest release
- Extract it into your libraries folder
- Rename the folder from
SPIFFSLogger-x.x.xtoSPIFFSLogger
See the summary below and try theexample. You may also want to take a peek at ourdocumentation.
#include<SPIFFSLogger.h>
This struct represents the data as stored in SPIFFS (including the timestamp). It is returned in any logger read operations.
Definition:
template<classT>structSPIFFSLogData{time_t timestampUTC;/** creation time in UTC*/ T data;/** data of type T*/};
This is the core of the library. You can create your logger like so:
// store ints, saving files in /log/ and keeping today + 7 days of historySPIFFSLogger<int>logger("/log",7);
We can also store a struct (which is probably more useful!):
structEnvData {float temperature;float humidity;uint16_t pressure;};SPIFFSLogger<EnvData>logger("/log",7);
This library uses the ESP8266 SPIFFS and built-in time functions so you must initialize those components and then calllogger.init().
Yoursetup() should look something like this:
voidsetup() {// configure time however you like, we use NTP herewifiSetup();// ommitted for brevityconfigTime(0,0,"pool.ntp.org");// initialize SPIFFS SPIFFS.begin();// initialize our logger logger.init();}
You must calllogger.process() in your loop to run the required operations (file updates and rotation). E.g.:
voidloop() {// your code is here logger.process();}
Simply calllogger.write() and the data will be logged with the current timestamp:
structEnvData data = {23.54,50.67,1020 };logger.write(data);
Reading the first row of today's logfile:
SPIFFSLogData<EnvData> data;logger.readRows(&data, time(nullptr),0,1);Serial.printf("TS: %d, T: %.2f, H: %.2f, %u\n", data.timestampUTC, data.data.temperature, data.data.humidity, data.data.pressure);
Or the last row:
consttime_t now = time(nullptr);constsize_t rowCount = logger.rowCount(now);logger.readRows(&data, now, rowCount -1,1);
Or 25 rows starting at the 50th:
SPIFFSLogData<EnvData> data[25];logger.readRows(data, time(nullptr),49,25);
Retrieving data from the last 20 minutes:
SPIFFSLogData<EnvData> data[25];size_t count = logger.readRowsBetween( &data,// output now - (60 *20),// time start (inclusive) now,// time end (inclusive)0,// start index within results25// max number of rows to fetch);for (int i=0; i<count; i++) { Serial.printf("TS: %d, T: %.2f, H: %.2f, %u\n", data[i].timestampUTC, data[i].data.temperature, data[i].data.humidity, data[i].data.pressure);}
Licensed under the GNU LGPLv3, see theLICENSE file.
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A minimal library for binary data logging in ESP8266 systems