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61  Using Arduino / Microcontrollers / Re: 6 pin male header for Arduino Pro Mini on: September 14, 2012, 06:44:44 pm
I think this is the one you need:
http://proto-pic.co.uk/break-away-headers-right-angle/
62  Using Arduino / Microcontrollers / Re: Problems with Serial Programming on: September 14, 2012, 09:43:42 am
Bad serial data will not cause flickering (aside from the regular 3 flashes after a reset).  You've got a bad contact somewhere, possibly on the CP2102 interface.  You tested the RX/TX loopback already, so it may be just the 5V output pin that's dodgy.  Try powering the breadboard from a separate 5V supply (not forgetting to common the grounds).
63  Using Arduino / Microcontrollers / Re: Optiboot with FTDI breakout removed on: September 13, 2012, 02:52:24 pm
Oscilloscope on pin 3
64  Using Arduino / Microcontrollers / Re: Optiboot with FTDI breakout removed on: September 12, 2012, 04:00:13 pm
I took your sketch, commented out the initial delay, and put it on a 16MHz Arduino Pro (essentially just an ATmega328 with a crystal and power supply).  With the FTDI interface connected or disconnected I couldn't get the sketch to fail -- it ran fine after a power-on reset or an external reset.  So I'm afraid I don't know what was causing the symptoms you describe.
65  Using Arduino / Microcontrollers / Re: Atmega328 custom bootloader on: September 11, 2012, 10:25:19 am
In addition to Ninoscript's comments, Pin 10 on the Duemilanove should be connected to Reset on the ArduPilot, not the other way around.  Are the grounds connected?
66  Using Arduino / Microcontrollers / Re: Leonardo 3x faster than the Duemillinove? on: September 11, 2012, 01:17:41 am
The Leonardo's instruction set is the same, so the calculation should run at the same speed.  However the USB "serial" interface is much faster: the data is never actually sent as old-fashioned serial, and the effective transmission rate is much higher than 9600 baud.

On the Duemillanove the serial conversion is a bottleneck.
If I run your code on an Uno at 9600 baud I get the same result as you: Found 1785 primes in 30 seconds
If I bump the baud up to 115200 I get: Found 4298 primes in 30 s
67  Using Arduino / Microcontrollers / Re: Watchdog oscillator frequency on: September 11, 2012, 12:55:27 am
The accuracy of the 8MHz RC oscillator is rated as +/-10%.  If the same applies to the Watchdog oscillator, then it might be that the design frequency is chosen so that the real frequency never (or rarely) exceeds 128kHz.
68  Using Arduino / Microcontrollers / Re: Optiboot with FTDI breakout removed on: September 10, 2012, 01:09:59 pm
It does sound more like the hang is happening in your code, and not in Optiboot.  If you'd care to post it somebody might be able to find the reason.
69  Using Arduino / Microcontrollers / Re: Optiboot with FTDI breakout removed on: September 10, 2012, 10:17:07 am
So does the Blink sketch run properly after reset with the FTDI removed?
70  Using Arduino / Microcontrollers / Re: Optiboot with FTDI breakout removed on: September 10, 2012, 05:47:51 am
I have not encountered this problem, although I've used Optiboot in many projects and I usually leave the RX/TX pins free to permit uploading new code.  Which version of Optiboot are you using?  Does this problem occur with the "blink" sketch?  Does it occur after a power-on reset?  Does it also occur after briefly grounding the reset pin?  Does it still occur if you ground Pin 0 before resetting?  After a reset does an LED on pin-13 blink 3-times?

A sharp photo of your setup would be helpful.
71  Using Arduino / Programming Questions / Re: Leonardo "Blink" contains USB code? on: September 06, 2012, 11:00:08 am
That's what I've done now, but I'm curious: what was the bug?
72  Using Arduino / Microcontrollers / Re: ATTiny85 without an external oscilator? on: September 04, 2012, 03:58:52 pm
Be careful with the terminology:  An oscillator is a circuit which generates the clock signal required by the CPU.  A crystal is just one part of one type of oscillator circuit.

There are two types of oscillator built into the ATtiny85:
  • One type uses an on-chip resistor and capacitor to generate an 8MHz clock[1].  It needs no external components, but it is not very accurate.
  • The second type requires an external crystal[2] plus two capacitors.  The external components take up space and cost, but the resulting clock is very accurate.  You can also choose any frequency, within certain limits[3].

It's also possible to use the clock signal from an external oscillator, but note that this is not the same as using an external crystal.

Normally the software runs faster or slower in proportion to the clock frequency.  However the Arduino software is clever enough to take the CPU clock into account, so delay(1000); always produces a one-second delay.  It also tries to ensure that Serial.begin(9600) always produces serial data at 9600 bits per second.

What the Arduino software can't do is account for an inaccurate clock.  The simplest thing to do is to use an external crystal, as these are manufactured to a high accuracy.  Alternatively you can tune the frequency of the internal oscillator, by adjusting the value stored in the OSCCAL register (check the datasheet for more details).

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note [1]: There is also a 128kHz clock, but most people will find this too slow.
note [2]: Instead of a crystal a ceramic resonator may be used.  It is slightly less accurate, but cheaper and doesn't need the extra capacitors.
note [3]: 0.4 - 20MHz for the ATtiny85, although crystals are only available with certain frequencies in this range.  Below 5V the maximum clock frequency is less than 20MHz.
73  Using Arduino / Microcontrollers / Re: ATTiny85 without an external oscilator? on: September 04, 2012, 11:43:54 am
It looks like the internal oscillator is just under 5% too-fast in that example, although the internal oscillator can be up to 10% off.  5% is pretty much the limit for reliable serial communication.  I think you'd need to either set the clock calibration register, or program the baud-rate generator specially to compensate.
74  Using Arduino / Microcontrollers / Re: Using pins A6, A7 on pro Mini compatible on: August 29, 2012, 12:05:29 pm
Nice job.  Did you use solder paste and an oven for the surface-mount components?
75  Using Arduino / Microcontrollers / Re: ArduPilot Legacy (Atmega328) on: August 23, 2012, 05:28:39 pm
Can you give us a hint as to what you're doing?  At least a schematic or a sharp photo of your setup, and a link to the code.
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