Thursday, 14 July 2011

Laser/IR code catcher

I put together a 'special' box to grab some IR laser coded transmissions (eg like TV remotes)

I needed something easily fieldable, so grabbing the defunct camera trigger box (with built in power switch, status LED and signal LED :) ) I velcro'ed a mini breadboard and ATMega328 board in.

The breadboard consists of a regulated 5V supply, a regulated 3V3 supply (for the SD card), an IR phototransistor/amplifier (nabbed from an old TV tuner box) and some voltage level shifters to allow the 5V MCU to talk with the SD card

Code after the break...

Monday, 11 July 2011

Back to square one... SD card gives up the ghost!

After leaving the 'weather station' running for 24 hrs (with an added light meter LDR :) ) I return to find the batteries flat and the memory card acting strangely (can see files but not read them or copy them!)

The whole card appears to be kaput! Windows cannot format and a quick google for this app:

doesn't work either. It appears that the card is NS. oh well. time to get on ebay for some replacement transflash!


Found a 2Gb micro SD in an old phone :) have installed it and updated my code so it opens, writes and closes the file on each write operation (hopefully this will prevent SD card corruption!)

Sunday, 10 July 2011

Weather station -improvements inc SD card data storage

Having an instant pressure and temperature readout on an LCD is kinda cool, but not hugely useful...

So I popped in an SD card using the SPI comms interface on the ATMega (plus a few resistors to drop the 5v signal down to 3.3V that the SD card uses) and can log CSV data that can be read by a PC later.

Next step - adding a real time clock so the board logs the current time/date rather than milliseconds from power on!

Code after the jump

Friday, 8 July 2011

weather station code

Basic weather station
Measures pressure and temperature from a BMP085 sparkfun sensor board
Power to the 3V3 regulator is sourced from digital pin 8
Readings are output on serial and to a 2x16 LCD (using a 595 latch to reduce the pincount needed to control the LCD)

Matt Wright 2011

Assorted code from various sources including:
SparkFun Electronics


Really simple 'weather station'

Stand alone BMP085 based weather station - measures pressure and temperature

Tuesday, 5 July 2011

New toys

Today I got an NCP1400 5V step-up board that takes any 1-4V source and ups it to 5V DC... Great for my supercap/solar PV cell power supply!

Also got the Sparkfun barometric pressure/temperature break out board BMP085

A little soldering of male headers and these boards are in action already! The pressure/temp board uses I2C, which is a bit more of a pain to code for than say analogue... However the example code gets the board up and running easily. Here's an example of the output in a spreadsheet...

The 5V step up board is great too - at the moment it's running from a dual-supply solar cell and supercap. The supercap is a bit underpowered, but a 60Watt lamp gives off enough juice to keep an LED going and charge the cap :)

##UPDATE - Got the 5V step up and 10F cap to power 'blink' sketch for about 2 minutes. Am now looking at low power methods with the ATMEGA chip so it wakes up, checks a sensor (stores the result) then drops to sleep again...

Monday, 4 July 2011

A closer look at the funky power regulator board. Vin and GND from the power source (7-12V - ideal for 9V batteries) goes in the top - 5V regulated and GND comes out the bottom. The capacitors are across the input and output lines to smooth out fluctuations.

The idea behind this board was to make a modular power system separate from the microcontroller board. This would mean different voltage supplies could be used for different projects (although variable voltage supplies could be an option... However I had a bunch of L7805CV ICs, so this is wot i made)
Hmmm... not many updates since I knocked together this camera flash trigger

Update on the flash trigger - its on hold until I can be bothered to find a cheap/free replacement laser diode for the one I fried with my cheap/nasty soldering iron...

Lots of other projects have started - most are still W.I.P. but I will try to document some of them here!

Here's a taster - my first microcontroller board sporting an ATMega328 and 5V power regulator in separate module. Currently runs the 'blink' sketch :]

Monday, 14 March 2011

Camera flash trigger project - circuit design

So my flash trigger is getting a nice box, and I'm ditching the breadboard in favour of stripboard (old habits picked up in AS level electronics die hard), but I want to keep the box innards as flexible as possible so I can put in new projects. To that end, I'm making the flash circuit separate to the power, input and output boards.

Two big issues with the current system - one, you can't easily align the laser without triggering the flash! This can be fixed by having an 'alignment mode' built in with a pushswitch to toggle between this mode and the flash mode. Another LED in the case will indicate which mode you're in :)

Problem two, you can only change the flash timing by uploading a new program. Not good in the field (netbook notwithstanding). Hence a plan to use the mode switch as a primitive timing selector by press-hold, tap out delay in 10's ms (say) and press-hold to set... The mode LED then flashes out the delay count (in 10's ms again) to confirm. My strategy is that of most modern hardware manfs - build in the bits in the box, then worry about writing software later on and release a patch :-] I'm looking at you Apple...

In the future I might look at using a segment display, but I reckon my 1990's digital watch approach should be workable :D

Oh, also I'm adding another circuit that can trigger my Canon SLR shutter to make the system more flexible. That kinda makes the flash delay bit make more sense I guess :-/

Camera flash trigger project - Boxing up

So my first try at boxing up involved an old network switch box (literally a switch to change between two networks). The metal box was OK for holding the arduino and a breadboard, but a bit rubbish when it came to power (required a USB source) and the wires were selotaped to the case... deffo dodge.

Quick trip to Maplin and I've now got a shiny ABS box for the arduino and circuit, plus a power pack, cable connectors (simple phono types) and a 1/0 switch to turn the whole thing on.

After a bit of drilling, hacking and hot glue, I have the following in-progress box:
Arduino box (top), laser remote (left) and LDR remote (right)
Main box with mounting point for the Arduino (from a motherboard mounting kit ;))

Phono jacks and holes for arduino USB and power

Saturday, 26 February 2011

Camera flash trigger project

When drops collide

OK so I've seen a few camera flash projects based on the Arduino, but here's my take on the problem: How to fire the flash to capture a very quick action on camera?

The first problem was 'how do I trigger a flash without frying my Arduino board and/or USB port?'...

Some digging around on the web and I eventually found that a camera flash simply works when its trigger pins/terminals are connected together, so no fancy digital signal generators etc required - unless you're talking to a modern flash with zoom, TTL etc :-/  That might be another project...

For my flash trigger I went wireless both for flexibility on where the flash can be positioned and because it meant I could trigger a nice low voltage wireless flash master instead of a buzzing, IC-melting, kilovolt flash unit :) My wireless trigger set is the el-cheapo Chinese type you can get from Amazon and Ebay.