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46  Forum 2005-2010 (read only) / Development / Re: ZIFduino on: March 27, 2008, 09:18:54 am
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The 7805 regulator requires 2 caps minimum.  Leave off the 7805 and say goodbye to 2.
Technically, the 7805 requires no caps for operation, only for increased transient response or (very) noisy supply lines. Arguably removing the 7805 necessitates the use of a capacitor or two because you're moving the power supply away from the system and all transients must be handled by capacitance.

Reading from the datasheet
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Cin is required if regulator is located an appreciable distance from power supply filter.
CO is not needed for stability; however, it does improve transient response. Values of less than 0.1 uF could cause instability.

In practise, the price of two caps is less than the worry of ignoring the gotchas.
47  Forum 2005-2010 (read only) / Development / Re: ATmega328P // 32k 28-pin dip on: September 28, 2008, 11:39:14 pm
These are finally in stock after several months on back order.
They're available bare for $5.25 Or pre-programmed for $6.25

Currently you'll need to use the hacked Arduino 11, but I'm making very strong progress with Arduino 12 and expect to have a version out shortly.
48  Forum 2005-2010 (read only) / Development / Re: ATmega328P // 32k 28-pin dip on: July 21, 2008, 01:50:17 am
OK, rocking and rolling. After modifying the bootloader, I can now actually upload code to '328s and squash a few bugs in my IDE modification.
I've posted some tentative documentation at http://spiffie.org/know/arduino_328/.

All of this is believed to work, but I'd like to hear from someone who actually has a >14K sketch (feel free to PM me).

Obviously unless you actually have an ATmega328P in your hot little hands, there's no point in downloading the modified IDE yet, as there are bound to be bug fixes. Linux and OS X versions will come along at some point. Assuming you can install a recent avr-gcc, the 'modifications' section contains details on most other changes required.
49  Forum 2005-2010 (read only) / Development / Re: ATmega328P // 32k 28-pin dip on: July 17, 2008, 04:40:14 pm
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I see mouser has got them but their on order  Mfr. Part #ATMEGA328P-PU would be really great if someone can point me to a place that has them in stock...
Mouser actually doesn't have 104 pcs on order, I called sales the other day to try to order them! There answer was sometime in late August (close enough to what the on-order dialogue says though).
As discussed, Atmel was targeting Q3 to begin full production, assuming they're on track for this target (and they meant the beginning of Q3), it will be a while before we see production batches making their way into distributor's inventories and even longer until we see these orderable in hundreds-of-units let alone small quantities.
This said, several distributors have parts and pricing loaded into their databases (Digikey, Mouser, Arrow, Avnet) but none show actual stock available. You can periodically use the Atmel distributor search to look for stock in all official Atmel distributors or findchips.
50  Forum 2005-2010 (read only) / Development / Re: ATmega328P // 32k 28-pin dip on: July 17, 2008, 03:08:24 am
After about 2 hours of hacking, my Arduino 11 Windows install can indeed compile code for the 328 and avrdude's config has been patched. Unfortunately I haven't bothered hacking the bootloader yet (it's after 4AM and I need to be up at 7AM to see the Microchip folks).

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C:\Documents and Settings\spiffed\Desktop\arduino-0011\hardware/tools/avr/bin/avr-gcc -c -g -Os -IC:\Documents and Settings\spiffed\Desktop\arduino-0011\hardware\cores\arduino -w -mmcu=atmega328p -DF_CPU=16000000L C:\Documents and Settings\spiffed\Desktop\arduino-0011\hardware\cores\arduino\pins_arduino.c -oC:\Documents and Settings\spiffed\My Documents\Arduino\Fading\applet\pins_arduino.c.o

C:\Documents and Settings\spiffed\Desktop\arduino-0011\hardware/tools/avr/bin/avr-gcc -c -g -Os -IC:\Documents and Settings\spiffed\Desktop\arduino-0011\hardware\cores\arduino -w -mmcu=atmega328p -DF_CPU=16000000L C:\Documents and Settings\spiffed\Desktop\arduino-0011\hardware\cores\arduino\WInterrupts.c -oC:\Documents and Settings\spiffed\My Documents\Arduino\Fading\applet\WInterrupts.c.o

...snip...

C:\Documents and Settings\spiffed\Desktop\arduino-0011\hardware/tools/avr/bin/avr-gcc -Os -mmcu=atmega328p -o C:\Documents and Settings\spiffed\My Documents\Arduino\Fading\applet\Fading.elf C:\Documents and Settings\spiffed\My Documents\Arduino\Fading\applet\Fading.cpp.o C:\Documents and Settings\spiffed\My Documents\Arduino\Fading\applet\core.a -LC:\Documents and Settings\spiffed\My Documents\Arduino\Fading\applet -lm

C:\Documents and Settings\spiffed\Desktop\arduino-0011\hardware/tools/avr/bin/avr-objcopy -O srec -R .eeprom C:\Documents and Settings\spiffed\My Documents\Arduino\Fading\applet\Fading.elf C:\Documents and Settings\spiffed\My Documents\Arduino\Fading\applet\Fading.rom

C:\Documents and Settings\spiffed\Desktop\arduino-0011\hardware/tools/avr/bin/avr-objcopy -O ihex -R .flash C:\Documents and Settings\spiffed\My Documents\Arduino\Fading\applet\Fading.elf C:\Documents and Settings\spiffed\My Documents\Arduino\Fading\applet\Fading.hex

Binary sketch size: 2934 bytes (of a 30720 byte maximum)


avrdude: stk500_getsync(): not in sync: resp=0x00
avrdude: stk500_disable(): protocol error, expect=0x14, resp=0x51
51  Forum 2005-2010 (read only) / Development / Re: ATmega328P // 32k 28-pin dip on: May 21, 2008, 03:03:35 pm
The pico-power chips come in both 10 and 20 variants (see ATMEGA168P-20PU and ATMEGA168PV-10PU).
Someone else could likely comment better, but my literature shows the Pico-power enhancements are primarily more/better sleep modes, so having both speed/voltage ranges still make sense.
52  Forum 2005-2010 (read only) / Development / Re: ATmega328P // 32k 28-pin dip on: April 08, 2008, 09:20:31 am
It took us about 5 hours to modify and test a code move from the Atmega168 to Atmega328P for another project; 4.5 hours of that was testing. We really just chose the '328 in AVRStudio, make'd, and I think we had to change one memory constant.

If you're not using the picopower bits (which the Arduino isn't), it's really just a 168 with more flash, ram, and eeprom.
I expect the Arduino code would require a modified bootloader (IIRC the bootloader address moved to the new top of ram location) and a new chip definition to use all the extra memory.

Testing the 328 with Arduino is on my todo list, it's just not at the top yet  :-/
53  Forum 2005-2010 (read only) / Development / Re: ATmega328P // 32k 28-pin dip on: March 18, 2008, 04:51:56 pm
I had to talk to an Atmel Sales rep anyway, who confirmed the Atmega328 is expected in production quantities for 2008 Q3 (so only a little later than LadyAda's ball-parking).
54  Forum 2005-2010 (read only) / Development / Re: Freeduino Mini USB on: May 09, 2008, 04:12:53 pm
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i like it a lot, i think it needs to have a 'pin 13' led tho so that people can do the 'blink' test. There's already a resistor so why not? (the resistor should come after the pin, i think...since the diecimila does that.)
As someone who'se designed them both ways, you want after the pin, otherwise you always have to remember that pin13 is "different". While having the LED/resistor and pin in parallel is different too, it's not as much of a consideration.
I whole-heartedly agree with the PIN13 LED. While I understand it might not alway be useful in a Stamp-like role, I think it's come to be an expected part and a key diagnostic bit.
Have you thought of using something smaller like the CP2102, if you're feeling squished.
55  Forum 2005-2010 (read only) / Development / Re: Stickduino - USB Stick sized clone board on: August 01, 2008, 12:43:44 pm
[SIZE=22]StickDuinos are now available.[/SIZE]
Their product page has some additional details (including the schematic, board, and parts list).
They're currently available fully assembled for just under $20USD, and there should be bare boards available soon.

56  Forum 2005-2010 (read only) / Development / Re: Stickduino - USB Stick sized clone board on: July 21, 2008, 02:12:22 pm
Any day now, I would expect later this week. I'm just waiting on time to push them through the assembly process and do the associated webwork.

I promise to let everyone know.
57  Forum 2005-2010 (read only) / Development / Stickduino - USB Stick sized clone board on: June 27, 2008, 04:09:06 pm

Everytime a small clone board is released, someone says something about how awesome it would be if it were a USB stick sized board. So here it is, a USB stick sized Arduino clone, the stickduino.

  • Small, 5.5x2.1cm not including the USB connector.
  • Electrically compatible with the Diecimila, FT232 based USB with auto-reset and 3.3V output.
  • All 8 analog inputs are broken out, thats two more than virtually every other board.
  • Pin 13 LED onboard and located near the end of the board.
  • Solder jumper selects 3.3V or 5V I/O operation.
  • Low voltage drop diode protects USB port from un-expected input voltages.

These won't be orderable until the SMT stencil for them comes in, but they do fulfil the awesome requirement anyway. Let me know what you think, comments, questions, suggestions, whatever.
58  Forum 2005-2010 (read only) / Development / Re: Arduino Nano on: May 23, 2008, 03:21:46 pm
Considering you have basically all of the Diecimila's components on a four layer board with double-layered assembly, I can see there's a noticeable cost increase.
Assuming parts costs are the same (which based on the volume of Diecimilas compared to Nanos, I think it's safe to say they aren't). You've basically doubled the PCB and assembly cost (two runs through the pick-n-place, two runs through the oven).

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If Gravitech wants to sell their (excellent) 4-layer Nano design for $50, why not? At the same time, others can sell an almost identical two-layer design for $25 or $30.
I think this is exactly the right way to look at things, there are a whole host of options, depending on what you want to buy.
Gravitech sells a pre-assembled, stamp-sized, official, Arduino for $50, that's one option and a pretty good option at that. Other than (possibly) price, it's a win on all aspects.
Ladyada sells Boarduino USBs for $25, they're bigger, kitted, and unofficial.
I sell iDuinos for $18, they're bigger, kitted, unofficial, and not listed on the Arduino.cc 'Hardware' page.
Paul sells RBBBs for $11, they don't contain USB, they're kitted, and unofficial.
There was a post recently about a clone stamp sized board with onboard USB.

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How many times has there been a comparison to the Basic Stamp that IIRC is priced at $50 and has always been railed for being too expensive.
And now, you can actually make the comparison properly. I don't see anyone rushing to replace the Diecimila with the Nano as the 'lead Arduino' board. If anything, this is a replacement for the Mini, in which case it's far more of an upgrade than a dramatic change.

Depending on what you want, you do have a range of options. The Nano is an excellent option if you need/want any of it's aspects and I think once you start imagining they're costs, you can see how $50 is a reasonable price point.
59  Forum 2005-2010 (read only) / Development / Re: Crystal uses (compared to ceramic resonators) on: July 08, 2008, 09:40:16 am
Quijonsith is correct, I dropped a 0 on all of the crystal measurements, and the "ordering options" does indeed indicate a native tolerance of +/-20ppm. I was however unable to find the stability option for either Mouser's or Digikey's offering. In volume these come as -X's with +/-20ppm. If you're saving a few pennies, -4H models are out there though, which is still only +/-0.003.5%.
Long term stability is given for 25yr lifespan at +/-5ppm, specs for the ABL's surface mount cousin (who's model escapes me) show a nice smooth graph ramping rapidly to about 4.5ppm within 5 years and then a slow rise to 5ppm over the next 20 years. It is not clear what ageing effects occur at temperatures other than 25c.

I apologize for lousy math on the crystal; most of my intention was to show resonator accuracy was within acceptable rates for many tasks. The crystal specs were shown for comparison of what could be achieved - lesson, don't do math at night, without using a calculator, then don't depend on it later to do more math.

With regard to pricing, those are /1000 prices. While commercial orders should be in the 10-1000K range, I'm fairly sure most thread readers are not budgeting their Arduino projects in that range.
60  Forum 2005-2010 (read only) / Development / Re: Crystal uses (compared to ceramic resonators) on: July 05, 2008, 06:02:27 pm
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I've stayed away from resonators and internal RC oscillators to avoid errors, since some of my stuff operates at temperature extremes (>100F in a vehicle in the Alabama summer, down to -70C in a high altitude balloon payload).
Most crystals/resonators are specked to nearly 160F, 100F is actually fairly close to the centre of the spec range. It's worth noting, that of the crystals and resonators I order, all of the resonators have a wider temperature range spec than all of the crystals. One resonator is specced for 145c (nearly 300F); the highest rated crystal is good to only 85c.
-70c is well beyond the operating range of most electronics, so I have no real comment on that. -40c is the lowest spec I see for both crystals and resonators. Don't most high-alt balloons include thermal insulation or even heating? Certainly all of the commercial high-alt weather gear I've seen does.

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Is it greater than double the worst case resonator error?
The datasheet shows a recommended +/-2.0 error rate for regular speed clocking, the worst you can do for resonator error is 1.1%, but keep in mind, to have double this, you need to keep one resonator at -40 and the other at +85. Even then you're below the max total error rate. Even at double speed, you're below the maximum allowed error rate.

If, however, you're really operating at -70 then at over +85, you're going to have bigger issues than serial com's with the resonator, the ATmega itself will need replacing, the FT232 it's talking to will need replacing, and the regulator will too... ...all of these will need to be extended temp devices, and even in this case, the usart error is still within the maximum allowable failure (and keep in mind, this is with two resonators, that both barely pass initial quality controls, in oposite directions, and have 10+ years of service life each, decaying in opposite directions). Given that even concocting this situation, we're still within the allowed error rates, I think it's safe to say a resonator is OK for a-sync serial comms. Keep in mind, any sort of synchronous serial is unaffected by these errors, so you have to be actually using the UART serial port at these temperatures.

I would suggest you try a resonator in your target application, unless it's time keeping I suspect you'll be pleasantly surprised.
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