Category: Arduino

Fan controlled by humidity sensor – design technique

This article gives an outline of the process used in designing the Fan controlled by humidity sensor to use my Generic heating / cooling controller design (hcctl).

Arduino thermistor thermometer – a tutorial gave a method for designing a thermometer based on a formula predicting the behaviour of the sensor. This article explains a different approach where that is not possible.

HDS10-02

Above is a characteristic from the manufacturer’s data.

The curves to no lend themselves to simple curve fits, so a cubic spine interpolation will be made based on key points from the curve.

Four our purposes, the mean curve (green) is sufficient for design.

Screenshot - 24_07_16 , 08_16_07

 

Above, the mean curve was digitised to capture the shape of the curve, 17 points were used.
Continue reading Fan controlled by humidity sensor – design technique

Last update: 24th July, 2016, 9:26 AM

Arduino app to set DS1307 Real Time Clocks.

I use a number of implementations of the DS1307 or DS3231 Real Time Clock chip, preferably the latter these days as they are considerably more accurate and compatible with DS1307 code.

In some applications, it is necessary or sometimes just better to preset the clock before connecting it into the application, and the need arises to set the clock ‘stand alone’. The method I have used for this has been clumsy and not as accurate as one might want for the DS3231, so this article describes a new solution.

IMG_1563

The solution uses an Arduino as the engine if you like. Above is an Arduino Pro, but a range of similar Arduinos would be equally suitable. ALso pictured are three RTCs, one connected to pins A2, A3, A4 and A5 providing GND, VCC, SDA and CLK respectively. Continue reading Arduino app to set DS1307 Real Time Clocks.

Last update: 29th May, 2016, 7:28 PM

Fox flasher MkII – high power 2 LED solar powered beacon

Fox flasher MkII – owenduffy.net described an animal deterrent based on an STC 8051 microcontroller and running from a single LiPo cell.

This article describes a further development using a solar cell, shunt regulator, 1S LiPo cell with protection board, and two high power red LEDs.

FF100Above, the unit constructed in a medium size Jiffy box, and a 6V 0.6W PV panel fixed to the top with silicone adhesive. The LDR is fixed to one end with silicone adhesive.

Two SM 1W red LEDs are fitted to opposite sides. They are 120° LEDs, the holes are countersunk to provide for light dispersion and the LEDs clamped to the inside with small brass brackets and heat sink rubber, a little silicone adhesive seals the holes. Continue reading Fox flasher MkII – high power 2 LED solar powered beacon

Last update: 22nd June, 2016, 3:28 PM

USBTiny

I bought a USBTiny AVR programmer on eBay for about A$8 posted.

HOT NEW Usbtinyisp AVR ISP Programmer FOR Arduino Bootloader MEAG2560 UNO R3 | eBay - Mozilla Firefox firefox 06/08/2015 , 08:24:12

 

Above, the seller’s pic of the package.

It is almost always the case that the ISP headers on the programmer use the standard pinout published by Atmel, and in that case the supplied ISP cables need to be pinned pin for pin, ie pin 1 to pin 1 etc.

If you look carefully at the pic, the key is towards the top of the pic which means pin 1 on the right hand plug is towards the viewer and pin 1 on the left hand plug is away from the viewer. The cable does not connect pin 1 to pin 1, and as a consequence the package did not work.

6wayDil

There is more than one way to connect these plugs, and above is one way that does connect pin 1 to pin 1, and the cable and USBTiny work. Though the seller has been told of this defect, he continues to sell the item with the pic of the defective cable.

One wonders how many thousands of these things are and will be sold with this defect.

 

Last update: 8th August, 2015, 3:32 PM

A tale of two USB-RS232 adapters

There are a number of USB-RS232 adapters available, among them Silabs, FTDI, Prolific and WCH.

The Silabs CP series adapters have been reliable but not very widely used.

The Prolific adapters are, well, prolific… but given their major compatibility problems and poisoned drivers, they are not a good choice.

FTDI was a good choice until they distributed through Microsoft Windows Update their device poisoning trick to disable chips they thought counterfeit… though they seemed to have backed away from that action.

The new kid on the block is an adapter by Chinese company WCH, chips that appearing in lots of low cost devices, eg Arduino Nano clones with WCH adapters instead of FTDI selling for around A$3+ on eBay whereas the FTDI equipped Nanos are more like A$12.

This article compares the WCH  CH340G and  FTDI FT232RL.

2USBRS232Above are two inexpensive adapters for Arduino boards, the upper one is FTDI based at A$8 each (inc post), and the lower one WCH based at 3 for $3.60 (inc post). Continue reading A tale of two USB-RS232 adapters

Last update: 16th August, 2015, 4:22 PM

Arduino HMC5883 magnetometer – a tutorial

This tutorial shows how to explore an inexpensive HMC5883 3 axis magnetometer module with Arduino.

The magnetometer module can be purchased on eBay at very low cost (<$3), and is an ideal educational project for the budding Arduino practitioner.

It is an ideal low cost project for a first exploration of explore I2C, and the basis for a digital compass. This particular module breaks out DRDY which is useful for interrupt driven applications.

Fig 1
Fig 1

Fig 1 shows the test setup:

  • at the top is a Arduino Pro 328 with Opti bootloader and FTDI adapter for programming;
  • middle is the HMC5883L module; and
  • bottom is a Logic Shrimp for logic tracing.

Continue reading Arduino HMC5883 magnetometer – a tutorial

Last update: 20th June, 2016, 12:56 PM

Arduino stepper motor – a tutorial

This tutorial shows how to explore an inexpensive stepper motor and driver board using an Arduino and included stepper library.

The stepper motor and driver board can be purchased on eBay at very low cost, and is an ideal educational project for the budding Arduino practitioner.

Fig01
Fig 1

Fig 1 shows the test setup:

  • at the top is a Arduino Pro 328 with Opti bootloader and FTDI adapter for programming;
  • middle is a Logic Shrimp for logic tracing;
  • bottom left is a 28BYJ-48 stepper motor; and
  • bottom right is a driver module based on UNL2003.

Continue reading Arduino stepper motor – a tutorial

Last update: 27th November, 2016, 7:07 AM

Arduino thermistor thermometer – a tutorial

This project was designed ad-hoc as a learning exercise for a friend who ‘needed’ to acquaint himself with Arduino.

What better than a practical exercise that demonstrates some key advantages and disadvantages of the Arduino environment.

The project was a simple digital thermometer to display normal environment air temperature, say from -20° to 50° using common and inexpensive Arduino hardware with firmware developed on the free Arduino IDE, all using hardware that was on hand. Continue reading Arduino thermistor thermometer – a tutorial

Last update: 24th July, 2016, 9:35 AM

I2C – LCD interface – Type 2

A range of inexpensive serial to Hitachi style LCD interfaces are becoming available.

This article describes the settings for one sold by eshoppingcity1 (and others) on eBay (about A$6 for 5 inc post at the time of writing but they are getting cheaper). It uses the Philips PCF8574T I2C expander chip which is supported by the user developed Arduino LCD Library V1.2.

Lc2I2c10 Continue reading I2C – LCD interface – Type 2

Last update: 5th August, 2016, 5:24 PM