Introduction: Arduino Datalogger With RTC, Nokia LCD and Encoder

By www.youtube.com/channel/UCFo2uTu

Parts:

  • Arduino Nano or Arduino Pro Mini
  • Nokia 5110 84x48 LCD
  • DHT11 temperature/humidity sensor
  • DS1307 or DS3231 RTC module with built-in AT24C32 EEPROM
  • Cheap encoder with 3 debouncing capacitors

Features:

  • GUI based on Nokia LCD and encoder
  • temperature, humidity, date and time can be stored every 1 to 120 minutes
  • each record is compressed to 39 bitfield only so 32kbit flash (4KB) can fit 819 records
  • optional AT24C256 chip can store even 6553 records
  • deep sleep used to save battery, ATMEGA is woken up by interrupts mainly
  • DHT11 is powered only during measurements
  • powered by single 18650 or other lithium cell
  • a few display "faces"
  • 6 fonts
  • battery level meter
  • data review and graphs
  • min/max with date/time
  • all recorded data dump via serial port in CSV format
  • LCD back light
  • own fast and low resource N5110 library used
  • own low level DHT11 data reading
  • own DS1307, DS3231 and AT24C32 I2C EEPROM handling code
  • the code uses almost all 32KB Arduino flash
  • all internal registers can be stored in external EEPROM or DS1307 internal RAM

Data compression

Following values are recorded:

  • time (hr,min)
  • date (d,m,y)
  • temperature
  • humidity

Above data is compressed to 39-bit bitfield:

  • hr 0..23 -> 5b
  • min 0..59 -> 6b
  • d 1..31 -> 5b
  • m 1..12 -> 4b
  • y 2018..2021 -> 2b
  • temp -40.0..64.0 -> 1024values = 10b
  • hum 0..100 -> 7b
  • total 39 bits

Only 5 bytes are used for 1 record:

bits   76543210    
byte0  hhhhhmmm    
byte1  mmmddddd  
byte2  mmmmyytt  
byte3  tttttttt  
byte4  hhhhhhh0

Step 1: Watch Videos

If you are interested in project features and development watch above videos

Step 2: Connections

Nokia 5110:

  1. RST to D9
  2. CS/CE to D10
  3. DC to D8
  4. MOSI/DIN to D11
  5. SCK/CLK to D13
  6. VCC to Arduino VCC
  7. LIGHT to D6
  8. GND to GND

DHT11:

  1. VCC to VCC
  2. DATA to D14
  3. NC
  4. GND to GND

RTC DS1307/DS3231 and AT24C32 EEPROM:

  • Arduino I2C (A4/A5)

Encoder:

  • PinA to D2
  • PinB to D4
  • Button to D3

Step 3: RTC Modules "LowPower" Modifications (optional)

In DS1307 cut 2 traces, remove R6 and make solder joint

In DS3231 cut 2 traces

Step 4: Firmware

Arduino sketch:

https://github.com/cbm80amiga/N5110_DHT11_logger_G...

N5110 library:

https://github.com/cbm80amiga/N5110_SPI

Configuration options:

#define USE_DS3231 -> to use DS3231 instead of DS1307

#define REG_IN_RTCRAM -> registers are stored in RTC RAM (only for DS1307)