Arduino Datalogger With RTC, Nokia LCD and Encoder

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)