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451  Using Arduino / Microcontrollers / Re: Attiny85 Invalid device signature... on: February 03, 2013, 05:22:56 pm
I presume you have just the one ATTiny85 so can't swap in a 2nd to see if the problem is common to both.

Nick Gammon has a sketch for detecting the signatures of all manner of Atmel processors, available for download here.  It needs the same connections as the ISP (explained in full on this page using an ATMega).

Does it find your ATTiny?

452  Using Arduino / Project Guidance / Re: Shift Registers on: February 02, 2013, 08:24:31 am

As dc42 pointed out, you sound like you have enough IO pins if you use the analog pins as digitals.  They're addressed as  A0=D14 through to A5 = D19.  If that's not enough for you, there are also other alternative to shift registers such as the MCP23008 or MCP23017 IO expanders which will give you 8 or 16 additional IO ports via I2C (using A4 & A5 on the Arduino, but you can have up to 8 of these without consuming any more than those two IO pins)
The 74HC595 can only output.
You can make it read too.
Are you certain?  I've always thought the 74HC165 was for shifting in (but I've been wrong often, and recently smiley )? 

Cheers  ! Geoff
453  Using Arduino / LEDs and Multiplexing / Re: Help with PWM led setup 7X2 on: January 30, 2013, 05:12:47 am

Which method did you run with in the end, and did you try them at 1/10th duty cycle at 1kHz PWM with 75mA current ?  How do they look?

454  Using Arduino / Microcontrollers / Re: Starting Out On AVR Programming on: January 29, 2013, 07:42:19 am
Someone was listening.  The latest episode of The Ben Heck Show (youtube) explains the difference between ICSP and serial bootloader programming before he launches into the day's project.
455  Using Arduino / Project Guidance / Re: Automotive datalogging - Lots of analog inputs needed. on: January 29, 2013, 07:15:40 am
Can someone also please confirm that if USB is plugged then it does not need a separate AC/DC adapter to get its power from ?
Confirmed.  It can draw its own power supply from USB when plugged into that, however be mindful it's only got limited capability to drive other devices so best you plan to drive all these sensors from an independent supply.
And what do you guys think of the PoE version ?
Great, if you have ethernet handy that you can power it from.  In a car there's probably simpler sources than setting up a LAN though.
Other vendors don't post them online it seems, but I expect it to be similar, that is with 0V, 5V and one signal pin.
That's the typical configuration for analog devices such as those.  Digital ones may need more connections (I2C has +5V, GND a data and a clock line for example) but multiple devices can share the same bus, only consuming 2 pins on your Arduino (in the case of the I2C example).

Looks like MoTeC knows they can charge a premium for their particular vertical market. 

Cheers ! Geoff
456  Using Arduino / Microcontrollers / Re: Starting Out On AVR Programming on: January 28, 2013, 03:42:07 pm

You have choices - you can leave the bootloader on there, and use it to help you get the program onto the chip via serial.  That's the way the IDE does it for your Arduino, and the bootloader is left in place on the chip ready to load further hex files ongoing.  Or you can overwrite the bootloader in the way that Sparkfun tutorial did and program the microcontroller that way.  The bootloader way is convenient if you use the IDE as your programming environment, and using the serial interface allows easy comms back to your PC for debugging and other output via FTDI whereas the other way gives you more flash to store your program in as there's no bootloader there taking up space and your program will start without the bootloader's small delay.

Buying bare ATMega chips is typically cheaper than buying them with the bootloader, and there are lots of sketches out there to load a bootloader on the bare uC too.

Here's some more good reading which includes some more background to this:
This one on loading and using the bootloader on a bare uC
And this one on updating a bootloader on another Arduino

Basically, there's no right or wrong way - it really is your choice.  HTH
457  Using Arduino / Programming Questions / Re: calendar/date maths - do any of the existing libraries do this well? on: January 28, 2013, 05:06:46 am
Thanks Bob - sometimes I can't see past my nose.
void breakTime(time_t time, tmElements_t &tm);  // break time_t into elements
time_t makeTime(tmElements_t &tm);  // convert time elements into time_t
There was my answer right there.  And, no 100th February 2013 now smiley
#include <Time.h>
  tmElements_t tmE;
  time_t atime;

void setup() {
  tmE.Second = 00;
  tmE.Minute = 00;
  tmE.Hour = 00;
  tmE.Day = 28;
  tmE.Month = 01;
  tmE.Year = 43;

void loop() {
  atime = makeTime(tmE);
  Serial.print(" ");
  Serial.print(", ");
  Serial.print (" is a ");
results in
29 1, 2013 is a Tuesday
30 1, 2013 is a Wednesday
31 1, 2013 is a Thursday
1 2, 2013 is a Friday
2 2, 2013 is a Saturday
3 2, 2013 is a Sunday
4 2, 2013 is a Monday
Thanks for the nudge in the right direction,
458  Using Arduino / Programming Questions / calendar/date maths - do any of the existing libraries do this well? on: January 28, 2013, 02:29:00 am

I've been looking at the Adafruit RTC library, the Arduino Time library and associated TimeAlarms library but none of these directly helps.

What I'm wanting to do is to choose an arbitrary period, add it to the current date and feed this into a variable (of DateTime or time_t etc) such that the month, year etc rollovers are taken account of.  If I do this with the Adafruit library for example
    now = DateTime(ayear, amonth, aday, ahour, aminute, asecond);
it will be quite happy to increment the day value out to the 100th of the month and beyond without complaining, so adding 7 to the day to construct a variable containing 5pm on the same day in a weeks' time can't be done this way (though curiously the unixtime() returned does appear to be correct, so it's possible I could reverse it back from that).

I'm happy to code around this, but thought it best first to check if it's already present somewhere.

459  Using Arduino / Project Guidance / Re: Automotive datalogging - Lots of analog inputs needed. on: January 27, 2013, 04:26:18 pm
Thanks for your clarification.  Typically shields can be stacked, though the caveat is that you need to assess the pin usage for each to ensure there are no clashes.  The website is very useful for determining this.  If you have a need that's not addressed by a single shield there is the other option of creating your own, by soldering components on a protoshield.  A further option is to use one or more breakout boards, or create your own and wire the Arduino to it/those.

Do you have a link to the datasheets for the sensors you will be using?  If they must be all analog there are a couple of ways to address them, either by switching many possible inputs and reading them via a smaller number of Arduino analog pins (eg 74hc4051 can switch up to 8 analog sources - the data sheet states switching time in the nanosecond scale); or using external ADC ICs you read the sensors with them, and pick up the values via digital pins on the Arduino.

There may also be digital variants of your analog sensors which would avoid needing additional intermediary ICs nor shields.  It's typical for accelerometers to be interfaced via I2C or SPI, and there are many digital temperature sensor types so I expect the number of analog channels you will need is actually less than the 64 you initially specified.

Cheers! Geoff
460  Topics / Science and Measurement / Re: Beginner with Chicken Project - Willing to pay for help on: January 26, 2013, 09:00:13 pm
Hi Stephen

Perhaps you could combine this with a load sensor so you can tell if the chicken leaves the nesting box but leaves it heavier than when she arrived there?

461  Using Arduino / Project Guidance / Re: 12 LED Charlieplexed Snowfall with AtTiny85 on: January 26, 2013, 05:47:22 am
I've been having quite a bit of fun with this ATTiny charlieplexing.  Aside from the KITT Larson scanner thing, most recently have made a little EMF detector (originally showcased here for Arduino)

With apologies for the lame iPad photo quality, here's that one constructed, and another take on the 20 LEDs, arranged in a square which runs a sketch that loops around changing direction every 0.5 to 5sec.

Dave thanks again for the original inspiration.
462  Community / Exhibition / Gallery / Re: 64 knob MIDI controller prototype on: January 26, 2013, 02:58:58 am
Wow.  I'm subbing here for the eventual link to your performance video  : )
Next step will be coming up with ideas for a nice enclosure.
I'm a fan of the Cisco router case featured in those photos - does it all fit back in there?

463  Using Arduino / Project Guidance / Re: frequency counter using optoisolator,arduino uno on: January 25, 2013, 05:28:05 pm
yea till 100 Mhz max.
Earlier you said 100Hz (100 cycles per second) and now you're asking for 100MHz (100 Million cycles per second) so that M makes a significant difference.  There is nothing in that circuit you posted that indicates it could get up to megahertz ranges either so did it work at all?

What is it you're measuring?  If you can provide a link to the datasheet for it that would be useful also. 
464  Using Arduino / Microcontrollers / Re: ATTiny85 tone() core? on: January 25, 2013, 05:11:14 pm
That clears it up perfectly - thanks !

465  Using Arduino / Project Guidance / Re: frequency counter using optoisolator,arduino uno on: January 25, 2013, 09:36:04 am
PIC16F628 is capable of measuring frequency only in 16Hz to 100Hz range.What about atmega 328p?
Is there any way to increase this range sir?

The first paragraph in the 2nd link above says it can give accurate measurements below 20kHz (20,000Hz) so is that sufficient for what you need?

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