Re: Wico XY Pattern Generator - Schematic capture complete

then you'll love some http://www.raspberrypi.org/
i dont think they konw how big its going to be :)
  ----- Original Message -----
  From: Clay Cowgill
  To: vectorlist@vectorlist.org
  Sent: Tuesday, November 15, 2011 6:58 PM
  Subject: RE: VECTOR: Wico XY Pattern Generator - Schematic capture complete

> I'm a big Atmel fan as well, but I've started using ARM's, and I probably won't
> go back. For my needs, the ARM ended up being cheaper than the XMega series.
> TI has parts with the Ethernet mac AND phy built in (all you have to do is connected
> the pins to a RJ45 connector with built in magnetics, throw in some firmware, and
> you're on the net!).

  Yeah, the bang for buck you get is kinda crazy on the ARMs compared to the AVRs, but for whatever reason (probably just past familiarity) I still find it easier to bash out AVR stuff faster. (Of course the last two ARM designs I did were an OMAP35xx and an i.MX53 and even Atmels new 200-400 page datasheets are *trivial* compared to the 4000+ page datasheet and 4000+ page user's manual on the bigger ARM SOCs!)

  I went to the TI Stellaris training a while back (got the little robot thing they gave away), but I haven't done any real designs with it. The built in MAC/PHY combo is cool though. Finding something that lashed up to the parallel PHY signals on the OMAP was a PITA.

> I only went with ARM because Atmel kind of screwed me on the ATXmega256A1.
> I had a datasheet, and an assurance from a factory rep that it was coming soon. One
> year later it hadn't been released, with no date given as to when (or even if) it was
> going to be released. I already had a board laid out and ended up having to redo the
> whole CPU section. (Grrr!) That's when I looked into the ARM series.

  I got burned on the ATXMega128A1 that supposedly supported x8 SDRAM. Except for the little detail in that it doesn't. Then the one that is going to have that capability has been on "next quarter" status for about a year and a half. ;-) OTOH, I do like their really small parts (Tiny13A, Tiny24A, Mega48, etc.) and kinda sprinkle them around on things probably more than I should.

> ST Micro, Atmel, TI, Freescale, etc all make ARM variants, so it's easy to change
> sources when different features are required (or a company screws you over).
> Programming them is like programming a PC. No more bank switching code (woo hoo!),
> and no more separate pointers for FLASH and RAM.

  I've used the NXP LPC24xx and the STM32 recently for clients. I like the STM32 quite a bit. Of course our present-generation emulated JAMMA setup is Atmel (the old ARM7 AR91R40008 ;-) and most of our 'commercial' arcade multigames were various ARMs too. (Atmel SAM9261 for the Sears Extreme Arcade, various speeds of the PXA270 for the Golden Tee Clubhouse Edition, Arcade Legends 2, Ultimate Arcade 2, etc.)

  I had a real unpleasant experience with the i.MX31 (we tried to answer "which operating system do you want to use-- Windows CE or Linux?" with "none of the above" and had a six-month detour trying to get the right information to use the 3D accelerator), then I had to *not* use the official PMIC because it wasn't available in a ball pitch that we could manufacture affordably so I had to DIY a power controller... and that was not much fun to make work right. FYI, if the clocks come up before the right power rail sequence on an i.MX31, you're calling 1-800-NEW-CPU. :-( And the DDR controller was finicky. Not much fun at all.

  To their credit, Freescale fixed a bunch now with the i.MX53 and that design actually mostly fired up first try (again some PMIC weirdness, but nothing fatal).

> The ZVG uses Atmel parts. Obviously a firmware update could turn the ZVG into a
> real nice pattern generator, but if I were to redesign it, I would definitely go ARM.
> They're just so damned easy to use, and with that kind of power, throw in an emulator
> and you have a CCPU on chip! It'd probably end up being cheaper as well, or at
> least very similarly priced.

  Yup. I'll say that I have a STM32F103RFT6 on a design with a vector generator right now. ;-) A half dozen years back we did an emulated vector system that used a raster display and didn't see the light of day, so we're bolting that on to a 'real' vector generator now instead. We still need to write a CCPU core, but we already have our 6502 and Z80 cores in ARM assembly which covers most of the rest of the vector titles we're interested in.

> For your design, you could probably have run the vector generator almost completely
> in the background, using the DMA controller and timers, and in the foreground run an
> FFT on the ADC inputs and based your patterns on frequency, beat, as well as amplitude.
> Same part count, similar cost.

  I really just used the XMega because we have one on our ArcadeSD board, so it was easy to hack the op-amps on and drive the laser from that without needing to do a new PCB. (We were having a chiptune concert at the arcade the next day and I wanted to bring something for visualizations, so it had to be zero-leadtime hack on something else. ;-) I must say though that the XMega's event system can really do a lot of interesting stuff too-- again, virtually a complete VG without any CPU-- but as soon as you start dealing with anything >8 bits the ARM really starts to shine, and certainly for emulation there's no contest.
   
  I still think it'd be fun to do a little Asteroids 'dongle' that just plugs in to the ILDA connector on a laser and plays the game directly without needing lasermame or a USB DAC or any of that stuff. Probably of very limited interest, but 'neat' counts for something. :-) At least with lasers you really only need to give it 'endpoints' and as the mirrors slew you get your 'line' as a result. But there's a bit of black-magic associated with getting the endpoints right that I never bothered to figure out. It worked "good enough" for what it was needed for and I left it alone after that...

  -Clay

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Received on Tue Nov 15 01:16:58 2011