Dangerous Prototypes Open Source Hardware

NYE POV project?

December 29, 2009, 02:35:29 pm

Does anyone feel like trying to knock up some code for one of these based on a pic in the next day or so?

http://hackaday.com/2009/12/28/new-years-party-favor/

the hardware is easy. but i couldnt do the code in the time frame.

im thinking a pic 18f or pic33f 28pin chip as i have a few of them spare and it would be heaps of i/o etc.

any takers on the code?

Re: NYE POV project?

Reply #1 – December 30, 2009, 03:28:51 am

Scorpia,

I'd have a crack at it, but I'm currently traveling for the next week. I could do it when I get back home!

At first blush it looks pretty easy. I could adapt some code I developed for driving a GLCD display, which already has a 5X7 character generator routine. I also think a PC application could be easily written to send data to the POV for storage/display. I've got a USB to Serial Converter (TTL levels) that would be just the ticket! One possible fly-in-the-ointment is that I write code in CCS C, and I haven't bothered to get/install the C30 compiler.

Any idea how fast the 'rows' are refreshed to make a POV work correctly?

John

Re: NYE POV project?

Reply #2 – December 30, 2009, 04:07:10 am

hhmmm,

next week sort of take the whole NYE surprise part away from the project

ah well. maybe its something we can have a go at anyway.

and sorry all i know about the project is whats posted . doesnt look that quick though as you can see the flashign change while he is holding it in the video.

Re: NYE POV project?

Reply #3 – January 05, 2010, 05:43:08 am

Hi,

Yeah, 'Happy New Year + 7' sure doesn't have the same 'ring', does it??? Oh well, such is life!

I don't have my embedded development, or PCB development, tools with me at the moment, but I do have my desktop software tools, so I wrote an application to send message data to the POV hardware.

http://www.flickr.com/photos/46123274@N07/4246319127/

I've also got a hand-drawn schematic which I'll redraw electronically when I'm back. Lastly, I think I've got a firmware program worked out that will do what I want. I'm sure it's got problems as written, but I can't compile or test at the moment.....

John

Re: NYE POV project?

Reply #4 – January 21, 2010, 10:35:54 pm

Hi All,

I don't know if anyone is still interested in this project, but here is an update. I've got a working prototype based on the PIC 16F689. It's a pretty simple design with just a handful of components, and a couple of connectors. It's built on a piece of perfboard, so mechanically, the design isn't ideal, but it's working. I've designed a PCB, and I'm going to send it off for fabrication tomorrow. I'm traveling for a week, so I should have something when I get back in early Feb. The firmware is basically complete, although I may continue to tweak the display delays once the board arrives.

John

Re: NYE POV project?

Reply #5 – January 22, 2010, 01:03:57 am

i am interested in this still john, i do think its another cool toy that would have a place around here.

keep the updates coming.

Looks like ill have to see if i can find one of those pics somewhere.

Peter

Re: NYE POV project?

Reply #6 – January 22, 2010, 11:16:07 am

I was scoping the upgrade to adafruits POV toy the other day. It's still serial.

Would there be any interest in doing a POV toy on a USB PIC? A bootloader for firmware upgrades, a virtual serial port for loading new designs with the existing tools. The 2550 has 256 bytes of EEPROM, but it can also self program, so the main flash can store designs too.

Just a thought.

Re: NYE POV project?

Reply #7 – January 22, 2010, 12:16:17 pm

i personally would like to see a usb pic used for some of this. the 2550 is easy as i have spares of then

Maybe we can also do 2 rows of led's to get 2 colors (plus blends) or even maybe rgb but im not sure if theres enough i/o and grunt for that.

I like the simplicity of the hand twirl. but the option of a motor driven one is nice as well.

Re: NYE POV project?

Reply #8 – January 22, 2010, 12:27:00 pm

I just did a quick check, the 18f2550 has 24 i/o available.

with 2 taken for the usb, that leave 22 available for leds etc. this would allow us to have 7 rgb led's without multiplexing. or maybe 12 with a 6x2 multiplex.

not sure how multiplexing would work for something like this. i suspect not real well

anyway. its an idea.

edit: i have in no way checked any of the otputs for suitability. so please take with a grain of salt.

Re: NYE POV project?

Reply #9 – January 22, 2010, 05:25:12 pm

I'm not sure how you counted the pins, but this comes to mind:

1 power
2 ground (?)
1 MCLR
2 program (might be reused)
2 USB
1 USB vreg

Re: NYE POV project?

Reply #10 – January 22, 2010, 10:11:04 pm

see i did no checking,

All i did was look at the data sheet. 24 i/o according to the data sheet.

so im guessing once we use usb ( 2+1) and icsp (3) then theres about 18 left. still enough for 9 dual color led's or 6 rgb led's.

but again, no checking other than simple maths.

Re: NYE POV project?

Reply #11 – February 25, 2010, 12:23:54 pm

I had a bit of a go with this tonight.

the schematic isnt finished , its more of a proof of concept.
I have used mostly dip parts for easy of use except for the rgb led's cause i got a few of the smd rgb's from seeed so i was thinking i would use them.
http://www.seeedstudio.com/depot/smt-1206-rgb-120-degree-p-88.html?cPath=32_38
At this stage i am assuming that the pinout of the sparkfun rgb led eagle part i used is the same layout as the seeed one, i still need to check it out to be sure.

I have managed to connect 7 x rgb led's to a pic 18f2550 chip. I have used jumpers to disconnect 1 led from the icsp pins for programming (still not sure if it would work) .

anyway here is draft version 1. If anyone wants to have a go at this then feel free,
Also for ian benefit please take these files as full open source with no restrictions from me.

As allways any comments are welcome

Re: NYE POV project?

Reply #12 – February 25, 2010, 12:49:38 pm

Nice job. You can use the two PGC and PGD pins like that, but I'm not sure about the MCLR pin. You can disable MCLR in the configuration. It might mean that you need a really long delay or some reset hackery to ensure that the power is fully stabilized before you start the program. Without MCLR you don't need R1. If it's PTH then you can program it out of circuit, and it's USB programmable and upgradable, maybe lose the ICSP header and jumpers?

Re: NYE POV project?

Reply #13 – February 25, 2010, 12:57:53 pm

Well the other thing i was thinking about is changing the crystal to one of the ttl resonators and just using the osc1 pin, freeing up osc2. that would mean we could not use the mclr and still get the 7 rgb led's. I think the longer term goal would be to make it all smd for size. so i think i would like to keep the iscp port for now. but if i went smd would it be better to go to the 18f4550 or another pic and get a full 8 rgb with extra pins free.

Also im a little bit of a loss for what to do with power. not sure if a couple of small button cells would be enough or if 4 AA batteries would be better. or some other option. either way im open for idea's

Re: NYE POV project?

Reply #14 – February 25, 2010, 01:07:43 pm

Freeing the OSC pin is a really good idea. As long as the resonator is accurate enough to drive FS USB. I don't know the number on that.

For SMD a 44TQFP 4455 is probably a good idea because it can be programmed in-circuit. that's a pretty easy package to solder too.

For the power, it might be easier use to a 3.3v 24fj USB PIC. More memory, more storage, runs down to 2volts, but no EEPROM. Probably add a big external eeprom for the amount saved by going to a 24FJ. Then it's only 2 AAs instead of a 5volt supply (or a multi-clock multi-voltage setup). But TQFP64 is the smallest chip available (I think, they always have new ones). This much power could do some fancy PWM stuff.