Arduino Projects of note

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I have some zs-042 RTC , it has a DS3231 RTC and what looks like an ATmega32 on it.

20141201 214606.jpg very good writing. also notes on using the eeprom are linked. <- this worked.

used this: ( worked )

also on board "AT24C32 EEPROM" ... a place to store data.

/rtc set


Liquid Crystal Display

Some notes:

Voltage Comparator Based Sensor

Picked up a soil moisture sensor from Deal Extreme ad 2.23 USD$

Sku 200142 1.jpg

It's based on a lm393 voltage comaparator. Many variation exist, for things like sound and light aswell.

This is an analog to digital sensor NOT a 1 wire sensor, so it soaks up an analog pin.


Arduino Code example:

LM 393 Datasheet:

This chip is a voltage comparator.

The board has d0 digital out and A0 Analog out.

Using the variable potetiomenter you can set the threshold where D0 goes high ( presmably ).

this is a good exmaple of how to "do" this circuit.

From analog to digital

So you got a bunch of cheap sensors, but they are all voltage oriented, like lm 939 and tmp36 and lm35, but you want to hook up a pile of them. wouldn't it be great if you could "convert" the voltage changing sensors to 1 wire or I2C ?

By using a buss ( like I2C ) you can attach many sensors to a single pair of arduino digital pins.

You can! Some notes so far below.

Analog to I2C

I2C What resistor

level shifting :

one I2C device many outputs

  • pca9685 ic

Working with data structure and EEProm

Measurting electrical usage with arduino

Amps with Arduino

  • use 0.01 Ohm Shunt resistor
  • arduino can measure 0 to 5 v in 4.9 mVa resolution. ( 1024 setps )
  • use op amp AD623ANZ to get volts up for arduino measurement.

YHDC SCT013-000 CT

measure amp and volts, non-invasively


multi tasking

other projects

Simple AD8307 rf power meter for sweeper using ad9850 dds and arduino for testing crystals etc

My Projects