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Forum Index : Microcontroller and PC projects : PIC32MZ and the Maximite
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| matherp Guru  Joined: 11/12/2012 Location: United KingdomPosts: 10248 |
Sorry if the word "pontificate" was inappropriate, no censure intended 
I looked at the 695/795 when choosing to do the 470 port. The problem is they are old parts, they don't have the facility to allocate specific functions to specific pins - it is all hardwired. This means that although they have all these I/O capabilities you soon run out of options if you want this+this+this. They also don't have pullups and pulldowns on all pins and they are slower than the 470. |
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| robert.rozee Guru Joined: 31/12/2012 Location: New ZealandPosts: 2437 |
i think we all pontificate in a sense, it is the nature of a robust debate where people put forward and defend their ideas. some ideas will withstand the test of peer review, while others will yield. as long as everyone is civil no harm should be done. my own views are driven by an inner frustration; i see a neat solution that fits (more or less) into a single chunk of inexpensive silicon... but then that solution moves away into the financial distance as (the essential) paraphernalia is added on. a little thought experiment. take a 32MX695 and place it in the middle of a double-side PCB that is the same dimensions of a credit card - 54mm x 85mm. give yourself a total budget of us$20. what else can you fit on the board without exceeding said budget? what compromises can you make? cheers, rob :-) |
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Grogster Admin Group  Joined: 31/12/2012 Location: New ZealandPosts: 9593 |
@ matherp - it's all fine. I was only worried that I may have been promoting my own ideas as some kind of "Way it should be done" - not intentional. Having re-read my posts above, it could be interpreted that way to some extent, so for that, I am sorry. I will proof-read my posts a bit more before I hit the POST REPLY button! 
@ Rob - Interesting challenge, but what about matherp's comments on the hardware side of things? Sounds like he has already checked that idea out as fart as the 695/795 chips are concerned. Perhaps one of THOSE(a 470 100-pin) in the middle of your credit-card sized PCB? Assuming $20, does that include PCB cost, or is that $20 just a component budget? EDIT: It begins!!!!!!!  
Conceptual drawing only, but I love a challenge, and you, Rob, have posted a worthy one! Smoke makes things work. When the smoke gets out, it stops! |
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| robert.rozee Guru Joined: 31/12/2012 Location: New ZealandPosts: 2437 |
when you type pic32mx470 into google, this is the first search result that comes up: http://www.thebackshed.com/forum/forum_posts.asp?TID=5893 
so it would seem that a MX470 is a (hardware) drop-in replacement for the 695, and that geoff had in july 2013 thought about it. going with the MX470 returns about us$5 back into the budget. yes, the us$20 budget needs to cover everything, including the PCB and cost of stuffing the SMD parts onto it. non-SMD parts can be soldered by the hobbyist to cut production costs. @geoff: given that the 32MZ is now out of contention, would the MX470 form a good core for a colour maximite III? rob :-) |
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| Grogster Admin Group Joined: 31/12/2012 Location: New ZealandPosts: 9593 |
Hmmmmmmm - not sure that is possible. Including the PCB, maybe, but the PCB and all the SMD parts fitted, all inside twenty bucks - challenging! The problem is mass-production. Many PCB houses will assemble SMD parts onto your boards for you for a fee, but you need to get at least 50 boards I think - it may even be 100 boards. You do get very good rates vs assembling them yourself though. The other option is to finish my flippin' reflow oven, then you could bake at least four boards at a time, and a correctly setup reflow oven will do four boards every 15 mins or so. Food for thought. Time for bed.  Smoke makes things work. When the smoke gets out, it stops! |
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| robert.rozee Guru Joined: 31/12/2012 Location: New ZealandPosts: 2437 |
grrr... been there, done that, never again! took ages to get the paste right, then place the parts while not disturbing any others. not to mention the inevitable tombstoning. i would far rather solder the parts by hand, and am quite sure i'd achieve a higher throughput. IF a board layout could be designed and everything fitted within budget, and IF geoff could be persuaded to come onboard and furnish the firmware, and IF a kickstarter campaign could be organized selling 1000 boards at us$20 each... sleep well, rob :-) |
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| plasma Guru Joined: 08/04/2012 Location: GermanyPosts: 437 |
I think a 20 euro/ dollar challenge isnt the right Way to make something cool. Playing with a cool gadget make a lot of fun and save 10 bucks is fun but only one time . Btw: what you think about teensy 3.1 and Mmbasic? |
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| matherp Guru Joined: 11/12/2012 Location: United KingdomPosts: 10248 |
Geoff noted that: This is still the case, seems like framed SPI is pretty much a Microchip invention. There is one post I've found where someone has got mono-VGA working well on the STM32 but no evidence that anyone has made colour work. The STM32 would make a very good Micromite though. Hmmmm......? |
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boss Senior Member  Joined: 19/08/2011 Location: CanadaPosts: 268 |
@matherp Peter, I have solution for STM or other CPU w/o framed SPI and VGA. I am in the middle of testing SSD1963 DVI shield based on Rayslogic.com development for Paralax Propeller. The shield use 8bit port + a few control signals. Resolution is up to 864x480@24bpp. It is fast, unexpensive and reliable, I got a written permission form Ray to use his design w/o any royalties for MM and uM. Reagards Bo |
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kiiid Guru Joined: 11/05/2013 Location: United KingdomPosts: 671 |
Refer to my post "Another graphic teaser". Not STM32, but Atmel, but pretty much the same thing. No external hardware, except for six resistors. I hinted a few times to Geoff that I can help a lot with the MZ stuff, but apparently for some reason his has been reluctant to seek my help about anything. I got carried away with other ideas meanwhile, but it is pity because the whole thing might have been done successfully already, should more collective approach was taken. http://rittle.org -------------- |
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| boss Senior Member Joined: 19/08/2011 Location: CanadaPosts: 268 |
@kiiid You mean out of the frying pan into the fire? You are a pure masochist aren't you? Never ever, ever ever! Bo |
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| Grogster Admin Group Joined: 31/12/2012 Location: New ZealandPosts: 9593 |
I am sure it is not the last part about being hurt by others, but from what I understand, Harmony, which you MUST use to program the MZ series chips(forget and throw away all you currently know about programming PIC's) is anything but harmonious, and would would indeed make kiiid - or anyone else for that matter who wants to take on the new Harmony way of doing things, a true masochist!
Once Geoff realised he was a masochist(in that he was prepared to take on Harmony at all in the first place), he began a recovery programme to get off it!
@ Rob - Never thought about the tombstoning thing with SMD reflow. You sound like someone who has had experience there, and does it happen often? I guess all it takes, is one side of the SMD part's paste to reflow before the other side, and up it pops, I would imagine - not that I have ever seen that or done any reflow stuff yet. You are making me wonder if I should bother! 
Smoke makes things work. When the smoke gets out, it stops! |
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| hitsware Guru Joined: 23/11/2012 Location: United StatesPosts: 535 |
> You are making me wonder if I should bother! Anything other than hole-thru is pre-masochistic
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| boss Senior Member Joined: 19/08/2011 Location: CanadaPosts: 268 |
@hitsware Good point! Thumbs up!
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| Grogster Admin Group Joined: 31/12/2012 Location: New ZealandPosts: 9593 |
LOL!
Well, indeed.
There are places for everything, I guess, and if you NEED the PCB footprint to be small, then you have little choice but to use SMD. If PCB size is not that much of an issue, then I agree - perhaps I will start designing for more thru-hole designs! Smoke makes things work. When the smoke gets out, it stops! |
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| robert.rozee Guru Joined: 31/12/2012 Location: New ZealandPosts: 2437 |
it happens often enough to be a right pain - and is far more prevalent on boards where the solder paste has been laid down by hand. i once spent a couple of days populating and reflowing 4 relatively small PCBs (credit-card sized), then fixing the many failures. later experience revealed that just doing it all by hand would have been both quicker and much easier. of course, if you are using BGA packages then there is little choice. have you added any more parts to the green fields of the raspberry mite? i have made up a short list of components in notepad: onboard parts: ------------- pic32mx470 procesor ceramic filter caps main crystal VGA socket PS/2 keyboard socket TC1262-3.3 RTC (was DS1307) RTC crystal offboard parts: -------------- SD card module backup battery 12v -> 5v stepdown converter zero-cost components: -------------------- 26x2 header for I/O port A (unpopulated) 26x2 header for I/O port B (unpopulated) 4x1 header for USB port (unpopulated) 4x1 header for audio output (unpopulated) 16x2 header for SD card module (unpopulated) 2x1 header for clock backup battery (unpopulated) 2x1 header for 5v in (unpopulated) zero-cost components are unpopulated footprints that the hobbyist to solder in themselves as required. strips of 40x2 header pins are dirt cheap. does anyone want to make up a BOM with parts priced? cheers, rob :-) |
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MicroBlocks Guru Joined: 12/05/2012 Location: ThailandPosts: 2209 |
I already designed something like that 2 years ago. The idea was to have the mpu on a separate plugin module so you would have just a processing module with all the stuff that is needed like caps and crystal. Then all the connectors to make it into something specific, like a color maximite by using another board. Like this: 
That would be all through hole to make it easy for a hobbyist. The mpu module would be all smd. 
That 'module' evolved to: 
and this: 
Until a in my eyes a disastrous kickstarter (Color Maximite) changed my view together with the arrival of the uMite. Then the 150 was actually more interesting,until it changed into a MkII with the 170 and now again changing into a 470. It is all getting better and better, but to build some parts that are a little bit more viable over the long term is the only way. So wait some time to sit out this 'storm' of new things then settle for a model, then produce some quantities to get an interesting price. Microblocks. Build with logic. |
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| Grogster Admin Group Joined: 31/12/2012 Location: New ZealandPosts: 9593 |
They look like excellent boards, TZA. Perhaps my work is done....
@ Rob and anyone else following my board: Have not added anything else to the board as yet, as it was just me playing about with the board size, so not sure it will go any further at this stage. It COULD form the basis of a big-brother to the SkinnyMite board though, I guess.... There is no harm in playing about, even if it proves to be impossible - it's all exercise for the little grey cells. Smoke makes things work. When the smoke gets out, it stops! |
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| robert.rozee Guru Joined: 31/12/2012 Location: New ZealandPosts: 2437 |
tzadvantage: the problem with the MCU32A core board et al is that the design philosophy looks to blow out the us$20 budget. what do you reckon the production cost of a set of your boards would be? the MCU32MX795 looks like it may be a commercial product that you sell - what is the retail price? darn those new things disrupting our lives! we need robust laws to prevent these new things ever being invented! but seriously, would such an approach not require never doing anything when faced with continuous progress? i am afraid there will always be a better processor due out in 'just a few months'. grogster: can i perhaps talk you into chucking just the component outlines onto the layout? certainly no wiring at all. if your cad package could spit out a 3D model, that would be absolutely magic. i still reckon (based upon just a little industry experience i have) that something could be put together that fits within the us$20 budget. all that is required is a little nous. if nobody else does, i'll look at fleshing out the BOM with some prices. cheers, rob :-) |
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| Grogster Admin Group Joined: 31/12/2012 Location: New ZealandPosts: 9593 |
Acknowledged - stay tuned to this frequency.
Seven after midnight here, so time for sleep. I will look into this tomorrow, and plop something up for you to look at. EDIT: ceramic filter caps main crystal VGA socket PS/2 keyboard socket All of those bits need other chips to support them, as the MicroMite in any of it's flavours does not use them. I could allow for/add a VT100 circuit as a 2nd chip if you like, which would turn the 470 into a very juicy VideoMite-ish clone, especially with the 100 pin 470 chip at the heart of it - LOTS of I/O potential, with the cheap VT100 driving basic video and dealing with the keyboard and USB. Thoughts? Smoke makes things work. When the smoke gets out, it stops! |
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