Search found 18 matches

by qwerty
Sun Nov 03, 2013 10:59 pm
Forum: LCDK: LCD & Keypad Shield
Topic: Live buttons on LCD shield!
Replies: 2
Views: 2694

Live buttons on LCD shield!

Is it normal for the metal buttons on the Freetronics LCD shield to be electrically 'live'? Well, some of the buttons on mine are live, and some not, apparently depending on the orientation of the button switch when soldered to the board. I have just gone to a lot of trouble, carefully machining the...
by qwerty
Sun Oct 20, 2013 7:58 am
Forum: Project Showcase
Topic: Improving ADC resolution
Replies: 17
Views: 16042

Re: Improving ADC resolution

It turns out that the achievable performance is even a bit better than I thought. As per the program examples provided within the Arduino IDE, I have allowed a 1 mS delay between analog reads, supposedly to allow the ADC readings to stabilize. However, in fact the averaged voltage reading seems to b...
by qwerty
Sun Oct 20, 2013 7:08 am
Forum: Project Showcase
Topic: Improving ADC resolution
Replies: 17
Views: 16042

Re: Improving ADC resolution

I must have been calculating the the bits wrong in my spread sheet ... oh well lol And i guess i was after a bit bigger range not quite to the level your talking about just a bit more but thanks for the input will get on with my build and keep an eye on this anyway may be able use it in something e...
by qwerty
Sat Oct 19, 2013 12:07 am
Forum: Project Showcase
Topic: Improving ADC resolution
Replies: 17
Views: 16042

Re: Improving ADC resolution

here is the figures i borrowed of the a forum and my tests in an oven confirm the results. using a 22K resistor the working range would be from 40ºC to about 260ºC and 33K 10ºC to 220ºC assuming 1 bit per 1ºC ... so that is why I would like a bit more accuracy mainly due to the large working range ...
by qwerty
Fri Oct 18, 2013 9:47 pm
Forum: Project Showcase
Topic: Improving ADC resolution
Replies: 17
Views: 16042

Re: Improving ADC resolution

hello qwerty, i'm not so much after ultra high accuracy but an increase in effective temperature range of the controller. I'm working with 1M thermistors from a maverick ET732 because i have them and there is a fair bit of info out there already. like this: http://hruska.us/tempmon/ I have also fou...
by qwerty
Fri Oct 18, 2013 8:35 pm
Forum: Project Showcase
Topic: Improving ADC resolution
Replies: 17
Views: 16042

Re: Improving ADC resolution

So how stable is the voltage reading of the dithered ADC, over time and with changes in room temperature? Naturally, I will run the circuit overnight, and see what it reads in the morning. To put the results gained so far into perspective, good-quality general purpose metal-film resistors specify a...
by qwerty
Fri Oct 18, 2013 11:34 am
Forum: Project Showcase
Topic: Improving ADC resolution
Replies: 17
Views: 16042

Re: Improving ADC resolution

So how stable is the voltage reading of the dithered ADC, over time and with changes in room temperature? It is certainly useful to be able to detect a change of say 1 part in 50,000, but it is a lot more useful still if the voltage readings are highly stable and reproducible over minutes, hours or ...
by qwerty
Fri Oct 18, 2013 8:07 am
Forum: Project Showcase
Topic: Improving ADC resolution
Replies: 17
Views: 16042

Re: Improving ADC resolution

Hi there are people interested like me for example please continue. It looks very interesting can't wait for the rest so i can build some thing... Sorry, I originally forgot to attach the circuit to the previous email, but it is there now. You are building a BBQ controller, so of course you need mi...
by qwerty
Fri Oct 18, 2013 6:04 am
Forum: Project Showcase
Topic: Improving ADC resolution
Replies: 17
Views: 16042

Re: Improving ADC resolution

Finally, the simple circuit for dithering an analog input, thus increasing the resolution from a painfully low 1023 counts to an equivalent of 50,000 counts or more, depending on how many readings are taken and averaged. For my case of 500 averaged readings taken at a 1 kHz read rate, the update rat...
by qwerty
Wed Oct 16, 2013 1:09 am
Forum: Project Showcase
Topic: Improving ADC resolution
Replies: 17
Views: 16042

Re: Improving ADC resolution

There doesn't seem to be that much interest in this stuff, but I'll press ahead anyway. Eventually I might post a summary on the Arduino forum. The first attachment shows the triangular dither waveform, derived from a 50% duty cycle square wave generated as a PWM signal on one of the digital output ...