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1  Using Arduino / Project Guidance / Re: small and thin Arduino, which one? on: September 01, 2014, 06:05:14 am
I'm too lazy to look it up on the datasheet right now to confirm, but I believe the ATTiny85 has only two hardware PWM pins. You can have as many software PWM pins as you like, though. An ATTiny85 should have no problem running two hardware + one software PWM pins.

Can it handle a software PWM while computing the change in output value from one color to next smoothly?  My color changing idea was along this line:
randomize new red, green. and blue value
calculate difference between current value and new value to determine increment rate
increment current R, G, B PWM value once per second
when the current R, G, and B value reaches the target value, repeat for new value.

Obviously with 3 hardware PWM, I could use wait 1 second before changing value. But with software PWM, I can't do that since I'd need to continuously toggle the pin on and off at millisecond interval to simulate PWM.

What about Digispark?? suggests 3 hardware PWM and it has built in USB support.  If the PWM pin isn't shared with those used for USB, I could tap into the laptop's web cam (which uses USB) and connect to that, allowing me to change (ie static color only or cycle between specific color for event or something) without having to open my laptop.  I never used the built in web cam anyway  smiley-cool (don't like the idea hacker could see me without my knowing so I unplugged it when I first got the laptop)
2  Using Arduino / Project Guidance / Re: small and thin Arduino, which one? on: August 30, 2014, 10:11:22 pm
The 5050 LED already inside is about 5mm by 5mm and it's oriented sideway to illuminate the small reflective plexi that makes up HP logo. Edge lighting design if I understand correctly.  The flat version looks like it'd work the best since it'd be easier to solder + heatshrink wires on it than trying to solder on the sides of that plcc-4 chip.

I've looked at ttiny85, as long as they are SMD and not DIP it may fit.  I don't know about the PWM, one article mentions 2 PWM pins and other mentions 3, the same pin is also used for USB connection.  Seems to me if I am trying to program it and test to see how it worked, the LED lighting might interfere with USB or serial communication and that might make reprogramming a bit messy.  I'd have to disconnect the LED if I need to tweak and reprogram.  I'll keep checking, I got whole weekend to figure out what works.
3  Using Arduino / Project Guidance / small and thin Arduino, which one? on: August 30, 2014, 09:10:38 pm
I want to mod my laptop and replace the built in lighted HP logo with an RGB LED.  The original LED is a white 5050 SMD LED but I think I can wedge a 5mm LED bulb if I file them thin with flat sides. There is a fixed 5v source that feeds the LED, it can do Arduino and a single LED.

I'm planning on using 3 PWM lines to control an RGB LED. As there's limited space between the LCD panel's back and the top cover, I can't use the regular parts like ATMega DIP chip.  Can someone suggest a tiny thin one?  Lilypad would work but a smaller one would be nice.

I do have UNO and the DIP chip can be removed and use the onboard USB connector for programming arduino that doesn't have onboard USB.
4  Using Arduino / Microcontrollers / Re: Difference between ATMega328 and 644? on: June 03, 2014, 08:20:40 pm
I came across the wiring diagram:

Same wires, different pinout. It seems I could use the custom ISP shield I made for '328 and whip up an adapter board to make it work with 644 and 1284. Now I need to find spare parts and order one of the 644 or 1284
5  Using Arduino / Microcontrollers / Re: Difference between ATMega328 and 644? on: June 03, 2014, 04:39:14 pm
And if they are not interchangeable on UNO board, can I use UNO as ISP to program a '644?  There's a 64k binary file I want to use and it obviously can't be used on any ATMega with less than 64k available flash.
6  Using Arduino / Microcontrollers / Difference between ATMega328 and 644? on: June 03, 2014, 04:36:52 pm
Guessing one has 64k flash but other than that, is there any difference or can I straight up drop a '644 into Uno board replacing the '328?

7  Using Arduino / General Electronics / Re: Want to try graphics LCD, does this exists? on: March 09, 2014, 03:58:46 am
Hmm about the right size and shape but those are mono. I was hoping for full color but I guess no one really makes long full color display
8  Using Arduino / Project Guidance / Using Arduino as Laplink interface? on: March 09, 2014, 12:15:35 am
I have an old laptop I want to save files off but here's a few problems:
hard drive is SCSI and SCSI to IDE converter is a couple hundred dollars plus finding 2.5" SCSI to 3.5" SCSI adapter would take time if it even exists:
no floppy drive
no CD burner and software for CD burner typically comes on CD but without driver, laptop can't see CD anyway so installing won't work
no USB
Laptop is pre-WWW era so no browser or internet connection
no Ethernet support

A dock on eBay is going over $200 shipped and are UNTESTED!!  Only 1 tested and working dock on eBay and seller clown wants $500 for it.

I do have a laplink cable that has RS-422 on one side and a spider of RS-422, RS323 (both 25 and 9 pin connectors) and I think 485?  I however don't have any computer that has serial port and local place has USB to serial adapters starting at $25.  I'd rather avoid this since it'd be used only once. 

Can I use Arduino somehow as a middle man for connecting legacy serial port on my laptop to USB port on my computer?  My laptop does have ZTerm program (Macintosh version of Hyperterminal) that can be used for direct serial to serial connection.  I have an UNO R2 with socketed chip I can remove to make it a dumb USB to serial adapter or leave Arduino for intelligent conversion. I also have Mega 2560 and Nano but chip are not socketed.

Or can I somehow use the Mega as SCSI to USB adapter? Wiring up 60 wires would take a while (50 wires for standard SCSI-1 plus power and ID setting)
9  Using Arduino / Installation & Troubleshooting / Re: avrdude: stk500_getsync(): not in sync: resp=0x00 Error on: March 07, 2014, 10:20:54 pm
Also it could be as simple as a bad USB cable. Try a different one.
10  Using Arduino / General Electronics / Want to try graphics LCD, does this exists? on: March 07, 2014, 10:08:52 pm
I wanted to build a panel to go onto my computer and display in graphics the status, and fit one standard bay slot.  I was thinking 128x32 LCD, does it exists in RGB and at the largest 5"x1.25" (125mmx32mm -about) The standard bay panel is about 150mm by 49mm so there would be bezel around and provide a mean of mounting LCD.  Smaller LCD can be considered but I'd like text to be readable

I tried eBay and found one about that resolution in RGB but it costs more than a single memory stick in my PC, seller wanted almost $200. :/  I found another that is OLED under $10 but there's  no mention of it being RGB and when I asked seller he said I could have red, green, or blue  smiley-eek I think it is mono with a choice of color background  smiley-razz

I have Mega 256 and could pick up LCD shield to interface with new LCD, assuming the LCD uses same type of pinout.
11  Using Arduino / General Electronics / Re: Best way to control multiple LEDs? on: October 19, 2013, 11:19:27 am
Yes, that's the output sequence in loop to make LED light seems to chase.  Right now I have a 555 timer and a 4013 flip flop IC but I can use Arduino instead.

These chips are designed to run as low as 3v but I've had them running stable at lower voltage when the circuit is running on slow clock (4 or 5 Hz)
12  Using Arduino / Installation & Troubleshooting / Re: avrdude: stk500_getsync(): not in sync: resp=0x00 ERROR on: October 19, 2013, 10:09:11 am
Also try different USB cable.  I've had cheap cable that went bad after just a few minutes of use and when I changed to a quality cable (one that came with my camera) the problem went away.
13  Using Arduino / General Electronics / Best way to control multiple LEDs? on: October 19, 2013, 10:07:04 am
I wanted to build a project that would have 4 output to create chasing LEDs effect
1 1 0 0
0 1 1 0
0 0 1 1
1 0 0 1

The output is the easy part (a pair of flip flop circuits can do it) but most IC do not take kindly to driving 100 LEDs per pin.

Available source is 2.5v and I plan to use white 3mm LEDs. How can I interface multiple LEDs to the chip so the current draw won't fry the chip?  Also at about 2.5v (less any voltage drop if I use silicon switching device) I won't need resistor.  Is there any drawback to having 100 LEDs in parallel?  If one LED is going to suffer thermal runaway due to defect, it'd just burn itself out then the rest of LED would continue as normal.

I could use higher voltage and resistor but I am lousy with SMD and wiring regular 1/8w resistor in a small project is going to be a messy rat nest of nightmare. (not to mention resistor + heatshrink tubes are thicker and would require redesigning) so I am hoping to just skip the resistor.

TIA for any suggestion!
14  Topics / Interactive Art / Re: Any Mandelbrot project I can copy for fun? on: June 23, 2013, 01:54:03 pm
Hmmm a cheap Due clone starts at around $40 and Arduino brand is around $55 plus I'd have to deal with 5v and 3.3v difference.
15  Topics / Interactive Art / Any Mandelbrot project I can copy for fun? on: June 22, 2013, 08:31:28 pm
I have a mega 2560 that's been gathering dust so I thought about using it to run a small color LCD module and do mandelbrot.  I searched by Google and the only one I found with detail readily available is a mono only.  I don't know if the code can work in color or not.

Does any of you know if there's a color version floating around?  What I'm hoping to get eventually (by tweaking code if needed) is one that has 2 mode: full auto screensaver-esque that continuously run, pause after completing for xx seconds, then zoom a random 1/4 of LCD and redraw that. And manual mode with either variable resistor or analog joystick to select a section to be zoomed.

Atari Lynx has something (hidden feature in Chip Challenge game) that has the manual mode I like but it's extremely slow running off 20 year old 16 bit CPU (plus a working Lynx system can cost around $50 on eBay).  Arduino Mega is considerably cheaper, more easily found, and can be customized.
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