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4291  General Category / General Discussion / Bootloader and FLASH / PROGMEM on: November 25, 2011, 09:58:24 am
Often the answer to huge variable constants is moving them to PROGMEM.  Sometimes people then ask if they can modify the data at runtime.  Ignoring for just a moment if this should be done, I have wondered what is the bootloader doing (or enabling) at allows it to write to PROGMEM that other running programs can't?
4292  Using Arduino / Programming Questions / Re: Writing to Flash Memory on: November 24, 2011, 11:30:50 pm
No, the running program cannot write to PROGMEM.

You might want to look into an external RAM or EEPROM chip.
4293  Community / Bar Sport / Re: Pin layout preferences on breakout boards on: November 24, 2011, 11:28:18 pm

4294  Using Arduino / General Electronics / Re: Breadboard to PCB on: November 24, 2011, 10:58:50 pm
SInce this subject never comes up and google doesn't have any results either, let me add that I've been using Seeedstudio since year 2009. Very happy with the quality of the boards, options, and price. They only test 5 of the 10 boards, but I have yet to find a failed one.

My only dislike is all boards have to be retangular. Some services will route shapes for you, Seeed does not.
4295  Using Arduino / General Electronics / Re: Capacitor Sizing on: November 24, 2011, 10:51:25 pm

I'm also thinking: How do car manufacturers do it? They have heaps of crap running that probably utilises 5V..  Clocks, radios, etc.  - Voltage regulator to reduce to 5V - but then these continually waste power through the drop.

Heaps?  Look at the size of your car battery and then look at the size of a AA.  Notice a difference?

Leave a car sitting for 2 or 3 weeks, it probably won't start.
4296  Using Arduino / Programming Questions / Re: Virtual Latching Relay. on: November 24, 2011, 12:18:39 am
A good start is to post the code you have now. State what works, and what doesn't.  In describing what doesnt it is useful to explain what happened versus what you expected.

That said, why are you using the analog inputs to read a high or low?  That sounds very digital.
4297  Using Arduino / Installation & Troubleshooting / Re: arduino pro mini 3.3v cant upload on: November 23, 2011, 10:41:12 pm
What is your USB TTL programmer?
4298  Using Arduino / Sensors / Re: Arduino Uno doesn't work properly when NOT powered through USB on: November 23, 2011, 12:39:41 am
Use Lithium if you can.  2-3 times the capacity of alkaline, and they hold their output voltage for longer.  Alkaline drops off relatively quickly.
4299  Using Arduino / Sensors / Re: Arduino Uno doesn't work properly when NOT powered through USB on: November 22, 2011, 11:29:02 pm
Is the 9V battery one of those small rectangle batteries?

If so, it is probably dead or close to it. Their current capacity is so low one would be exhausted in a matter of minutes with a high current draw device like a motor.

Also are the motors powered directly from the battery or through a regulator (like the 5v reg used when you aren't powered through USB. )
4300  Using Arduino / Programming Questions / Re: digitalRead/if error: runs through code, despite if's on: November 22, 2011, 09:48:33 pm
However, when I add a resistor the Arduino goes in a high to low, then low to high cycle, even when no current is being passed through. Without a resistor the arduino still does that, but is not as fast of cycles as with a resistor.  smiley-roll-sweat

Is that resistor connected to 5V, GND, or just in series with the wire? It needs to "pull up" or "pull down" to a high or low.
4301  Using Arduino / Installation & Troubleshooting / Re: Arduino UNO won't connect to computer (I've already read the forums!) on: November 22, 2011, 09:43:40 pm
Are you connecting to a USB Hub?  UNO and OSX don't always get along in that case.  Since some of the ports on a Mac are actually on an internal hub, try all the other ports.

Look at System Profiler (refreshing when you connect or disconnect the Uno) to see if OSX sees anything.

Also, drop into the terminal and run "sudo dmesg" after connecting, to see if the kernel is giving any hints.
4302  Using Arduino / Programming Questions / Re: summing sensor readings on: November 22, 2011, 09:39:11 pm
What do you mean "select your code and press a button #"?

First, edit your post. Then wrap your code in code tags, the "#" button in the editor's toolbar.
4303  Using Arduino / General Electronics / Re: Starting a golf cart using Arduino (EZ-Go) - powering a LARGE DC motor on: November 22, 2011, 09:33:24 pm
Look at the size of wires on the batteries and the size of the wires on the key switch. This will quickly confirm the switch is a low voltage, low current path.

The key doesn't start (or run) the motor. It simply enables it to function.
4304  Using Arduino / Installation & Troubleshooting / Re: Flashing Arduino 2560 with AVRdude and Eclipse on: November 22, 2011, 01:59:23 pm
Have you tried using -carduino?
4305  Using Arduino / General Electronics / Re: 3.3v logic to 5v logic on: November 22, 2011, 01:17:15 pm
3.3 > 5v smiley

(3.3 from a LPC microcontroller)

Okay, so that's more cryptic than what you said before.  Can you use words this time?

3.3 from a LPC to what?

If you want the outputs of a 3V3 device to connect to the inputs of a 5V device, no shift is probably necessary.  The high threshold of the 5V device is probably low enough to detect a high for 3V3 logic.
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