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1  Using Arduino / Microcontrollers / Re: Add a SIMM to your Arduino :) on: April 11, 2014, 01:06:27 pm
haha... i LOVE steam punk.

actually while its true that using flash for most ram applications will destroy it in jig time that wouldnt be the main drawback which is write access. hundred times slower than flash. just wouldnt work for the kind of use ram is required, ie dso, frame capture, logic analyzer, etc. and serial ram is not cheap and not fast in my experience. realistically though sram might be the better choice there.

as far as capacity i was careful to mention mega (arduino mega) in reference to the  256kbyte comment. i do plan to give that a try but probably using m1284. even though that chip already has more ram than any other avr it sounds like a really cool rainy day project.

2  Using Arduino / Microcontrollers / Re: Add a SIMM to your Arduino :) on: April 10, 2014, 04:18:58 pm
joe, you dont seem to recognize the difference between ram and flash. by my calculation only .05% of cpu time to refresh and 256kbyte not 4kbyte. using mega on that same simm would give 256kbyte. i have i huge box of those am tempted to give that a try.
3  Using Arduino / Microcontrollers / Re: AVR Programmer on: April 01, 2014, 05:07:53 pm
I can't get it to program the Atmega8

 sorry, i was replying to the m8 comment, ive no experience with trying to do atmel 8051 variants using arduino as isp. i dont know anybody who has succeeded there either. personally i use custom socket board and software to do those.

btw, nice adapter board.

4  Using Arduino / Microcontrollers / Re: AVR Programmer on: April 01, 2014, 02:48:36 pm
I was hoping I could connect RX to MISO and TX to MOSI directly, but it appears I need other components.

actually it is possible to use a serial port to directly program avr (see ponyprog etc) but arduino as isp is easier and more reliable. if you have trouble with m8 its most likely a wiring error because there is no difference between that and t45 regarding programming algorithm.
5  Using Arduino / Microcontrollers / Re: Arduino @ 8MHz instead of 16MHz on: March 22, 2014, 07:34:29 pm
lol! obviously i was just trolling for trouble with that one.

seriously though, arduino chips are just about the best of the bunch for directly powering from batteries with 3v-4v being a good range. i forgot to mention the highly popular 3.3v dc supply fits right in there and that can be had from just about every ftdi dongle. " we doe neeeeed no steeenkin' 5v"
6  Using Arduino / Microcontrollers / Re: Arduino @ 8MHz instead of 16MHz on: March 21, 2014, 04:59:26 pm
1. rasy is right. except its "caveat insurancium compania".  ive personally run torture benchmarks on several part numbers for 3v@8mhz from freezing to boiling w/o issues. ok for hobby. apparently many commercial too judging from the market.

2. osc drifts very little during temperature but more for voltage. rs232 is workable for direct lipo power (4.2-3.6v) but only if properly calibrated at median. the real problem is divisors just dont work out for 115kbaud @8mhz. thats why a reasonably designed bootloader would choose 57k as default. little to do with osc stability.

3. no need to change bootloaders going from 16mhz to 8mhz. one size fits all. simply use next baud rate down.

4.  regulators would not "just eat too much power". ldo which is the only type that makes sense here draw picoamps.

5. "code" is not  always a mass noun. ie "morse and enigma codes proved useful during the war".

ps lipo or 3 rechargeable aa cells no regulator are personal favorites for 99% of my projects. they are really interchangeable.

7  Using Arduino / Microcontrollers / Re: Optiboot on Arduino Pro Mini 5v 16MHz not available on: March 21, 2014, 04:25:46 pm
Trouble is: There's no "Uno" either.

mainly because uno, duemilanove, promini, and aprox 200 others are all the same as far as that menu goes. the only ocd are those who demand a different entry for every brand of 16mhz board. if they had their way it would be several pages long and since gets truncated only 1% visible. 5-10 minutes to get to your particular favorite.
8  Using Arduino / Microcontrollers / Re: (solved?) Sudden power jump in sleep mode on: February 25, 2014, 01:32:16 pm
he already set pins to outputs which does the same thing. looking more and more like it was the ldo. unconnected pins there can also cause spurious draw. specially those 2980 clones.
9  Using Arduino / Microcontrollers / Re: ATMega328P on BB, no sign of life on: February 25, 2014, 11:38:54 am
Speaking of which, any cheaper alternatives?

my favorite is ebay usbasp for 2$-3$.  i found it more reliable and easier to use than my dragon or mkII not to mention you can buy a dozen or more for the cost of one of those. arduino as isp would be my second choice.

maybe try simple blink program before getting into bootloaders. if that works then the problem is unlikely the programmer.
10  Using Arduino / Microcontrollers / Re: Sudden power jump in sleep mode on: February 25, 2014, 11:25:05 am
under some conditions unconnected io can cause exactly that symptom. waving your hand 2' away could result in 1ua or 1ma jump. or just sitting there gates drifting down into threshold can do this.

also be aware that unless the ldo is actually removed from the board ground current can vary with unconnected terminals too.
11  Using Arduino / Microcontrollers / Re: Burning boot loader without reset resistor on: February 16, 2014, 07:50:11 pm
well if you just scroll down a bit, you'll find a "minimum circuit" that don't even have a xtal and capacitors.

in my minimum mega8 ardiunoisp design, except for pwr bypass, there are no external components at all. so far ive built several dozen of these for others with no problem. also with modern crystals and proper fuse settings theres less reason for those two caps there.

but if you want to run the target avr after you unplug all the wires to your arduino, you'll want that 10k res (instead of connecting RESET directly to VCC) anyway.

i disagree. for some reason builders, specially hobbyists, like to attach as many unnecessary components as possible. in the case of reset circuit it often creates far more problems than it solves. in particular throwing in caps which turns out to be a major reason nooby circuits wont program.

imo NOTHING is the best thing to hook up to that pin. as long as you dont go around poking it with metal tools or place megawatt welder 1" away problems are rare. of course, as always, for mission critical applications its best to adhere to atmel specs to the letter. not so much for technical but rather liability reasons.
12  Using Arduino / Microcontrollers / Re: Burning boot loader without reset resistor on: February 16, 2014, 01:22:10 pm
for modern arduinoisp the resistor serves no purpose during isp programming. for uploading via serial, depending on vcc and level of the dtr signal, the 10k resistor can be eliminated there too. the internal avr one is sufficient. all mine work fine w/o. for cases with mismatched voltage (ie 3v ftdi w/5v avr) a 10k to 3.3v works every time so considering how cheap they are it dont hurt to tack one on.



13  Using Arduino / Microcontrollers / Re: ATmega's internal oscillator - how bad is it? on: February 16, 2014, 12:52:23 pm
its actually true that internal rc 8mhz clock provides more reliable 115kbaud communication than with a crystal (i remember when this statement almost got me run out of town... my how things have changed. lol). internal is my preferred setup these days, not only because those two crystal pins become available for io, but its the ONLY way to implement a truly accurate avr low power calendar clock (watch crystal). this cannot be done with the standard arduino 16mhz.
14  Using Arduino / Microcontrollers / Re: How can i use ATMega328p-pu as a FTDI ? on: February 15, 2014, 02:45:46 pm
its not a waste if you have a mega328 in your hand and dont want to wait 5 weeks for tiny85 or ebay converter from china. or pay $15 for domestic with shipping. heres a simple avr usb/serial converter that uses the same driver as usbasp:

http://code.google.com/p/picoboot/source/browse/trunk/usbdrv/usbdrvasm8.inc
15  Using Arduino / Microcontrollers / Re: How can i use ATMega328p-pu as a FTDI ? on: February 14, 2014, 01:48:10 pm
actually the fischl code and the ebay baitemcu units do not have serial converter routines like found in the ebay lsoft units. i did manage to locate m88 binary couple years ago which was m328 compatible and flashed a few promini boards as usb adapters but stupidly locked the chips. now i would like to get that back but the old links are dead. im told some chinese sites have it but theres a language barrier.

it would be fairly easy for a motivated individual to mod the fischl source but being one of the laziest people on earth, "it aint me babe".  if i cant get ready to load hex then those $1 ebay converters will have to do me.
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