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Forum Index : Microcontroller and PC projects : Growing a Maximite
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| MOBI Guru  Joined: 02/12/2012 Location: AustraliaPosts: 819 |
Hi all, I have two colour MMs and am really having fun with them. I wondered If I could grow one from the ground up, so to speak. I have made a lot of PCBs using the Kinsten method (UV)and wondered how hard it would be to etch a 100 pin pic32 footprint. I am staying with Downwind so we decided to give it a go. The trace size is about the same as for "through pin" tracks with which I have had fair success. The 100 pin fotprint is a bit more daunting, but we did up some artwork on plain paper using a mono Brother laser, exposed and etched a board. The board turned out quite good although the tinning rippled up a bit. No shorts and no breaks. So far so good. Now I wait for my pics to come for the soldering bit. I know one can purchase boards like this one from futurelec (and I have some on the way @ $1.25ish each), but wanted to try it anyway. 
Work in progress. It is only the hardware I'm tackling. I intend to load MMbasic. David M. |
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| paceman Guru Joined: 07/10/2011 Location: AustraliaPosts: 1326 |
There's another converter board here 100 pin 0.5mm converter about the same size and with SMD support passives already mounted. At $1.69 it's pretty good. I got a couple and they look the part - yet to put the PIC on though - a bit chicken I think! Greg |
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| MOBI Guru Joined: 02/12/2012 Location: AustraliaPosts: 819 |
Do you want to wait until I get the 100 pin pic32 chips and see how I go before trying them yourself? Have you read Geoff's article on his web site on smd soldering by hand? It is under the maximite mono construction section. Worth a read. PS. I had a look at the site you posted - very cheap and impressive - there are even better prices if you go looking. However, my aim is to build it all from the ground up, the idea being that if it can be done "home grown", it will be so much easier using the "ready rolled" versions of boards. That way, others may be tempted to take the plunge. David M. |
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| robert.rozee Guru Joined: 31/12/2012 Location: New ZealandPosts: 2288 |
i had a couple of those ebay adaptor boards arrive last week, with a view of building up a few colour maximites using only wires - no main PCB. there are SD card boards available on ebay for only a couple of dollars that bring the pins out to an 8x2 header (auction number 280780639068), and the VGA components will be suspended on the back of the d-sub socket. soldering SMD ICs is pretty easy, you just need to use LOTS of flux. you don't try to solder individual pins, but instead use your iron to 'drag' the solder across the pins such that as you go the flux causes the solder to un-bridge. then just tidy up the odd bridges with solder wick. the only problem is how to get the bootloader into the PIC32... can anyone tell me the cheapest option for achieving this? i've been looking at a thing called a PICKIT2 (ebay auction 251195999655), or is a PICKIT3 needed? |
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| MOBI Guru Joined: 02/12/2012 Location: AustraliaPosts: 819 |
I bought a Pickit3 for that purpose - unless someone knows a better way, I think it is the easiest. I haven't tried it yet but looks straight forward enough. They should be available for sale in NZ. I am waiting for some blank pic32 chips to arrive to try things. Thanks for the tip on the smd soldering. I had an old board that had a similar size and style of smd chip. I desoldered it with a heat gun and using some tin paste, resoldered it back on the board. All lined up ok and no bridges, so am confident enough. I'll let you know in a few days hopefully. I am away from home for a few days so not much will happen until I get home again. Perhaps we can do this thing together or at least swap notes. David M. |
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| paceman Guru Joined: 07/10/2011 Location: AustraliaPosts: 1326 |
I've got a brand new unpacked Pickit3 and a couple of blank PIC32's waiting for me to have a go. I've read Geoff's SMD info, watched a few YouTube videos and soldered a few SMD passives without any hassle so I'm not so much worried about the soldering as I am with the programming with the Pickit. Haven't gotten round to reading all the stuff on the MicroChip site about using the PicKit yet though and I think that might be wise before I start. The break-out board you've done looks impressive - next stop a full project board with the 100pin PIC and all done without piggy-back boards! |
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| MOBI Guru Joined: 02/12/2012 Location: AustraliaPosts: 819 |
Yair right! (mind you, I might, thought I suspect I'll "just" make an I/O board and plug in the pic board. Don't really have the facilities to do double sided board). As for the pickit3 - as long as you don't use the button on the programmer and only the pc (MPLAB.IPE) controls, you shouldn't have any troubles. It depends on whether you want to wait until I do the guineapig thing. The pickit3 is very much like my home grown programmer - the only difference is that the comms protocol is not the same, and I couldn't find the commands or format, so I went and bought one. You don't get much for your money!!! David M. |
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Grogster Admin Group  Joined: 31/12/2012 Location: New ZealandPosts: 9063 |
@ paceman: A little hint from a fellow Aussie on that aspect... 
Skip through to about 20 mins for the 0.5mm pin-pitch PIC soldering. I have to say that I love this fella's enthusiasm - his attitude and nice close up videos have actually convinced me to try some small SMD - something I always steered clear of before due to the perceived problems in soldering. However, I think that a proper soldermasked board will make it much easier, as the solder won't want to bridge so much - or so he says...  Smoke makes things work. When the smoke gets out, it stops! |
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| paceman Guru Joined: 07/10/2011 Location: AustraliaPosts: 1326 |
You doing the guineapig thing sounds perfect - ahem! I read the stuff about that button - I think before I start messing around with it I'll do as someone suggested and glue a little grommet or something around it to stop accidental pressing. |
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| paceman Guru Joined: 07/10/2011 Location: AustraliaPosts: 1326 |
That was one of the tutorials I watched but it was getting long-winded and I gave up about five minutes into it. As you say, he's good though and his close-up videos are very good. |
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| Grogster Admin Group Joined: 31/12/2012 Location: New ZealandPosts: 9063 |
Yeah, he does go on a bit, hence my giving you the 20 minute index... Smoke makes things work. When the smoke gets out, it stops! |
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| MOBI Guru Joined: 02/12/2012 Location: AustraliaPosts: 819 |
Re the PICKit3 programme button.. I found that it does take quite a bit of pressing (at least mine does), so I think accidental pressing without a hex file loaded is not too much of an issue, but I do agree, some cover or or grommet is a good idea. Still haven't found out what really happens to the pic32 if the button is pressed and no hex file loaded. I ordered some 100 pin stamps from futurelec well over a week agon now (visa card) but no sign og the boards nor any sign of debit to my visa card. I have heard that orders sometimes take months to deliver. Hope this isn't the case here. I might have to etch a few more boards of my own. I did consider spraying the whole board with PCB varnish and then scraping it off the pic32 foot print to try and prevent solder bridging. We'll see unless someone else has tried something better?? David M. |
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| JohnS Guru Joined: 18/11/2011 Location: United KingdomPosts: 3659 |
I don't think "no hex file" will trigger the problem. John |
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| MOBI Guru Joined: 02/12/2012 Location: AustraliaPosts: 819 |
I have a few pic32 chips coming. I'm prepared to have a go at "loading" the PICKit3 with the MM hex file, disconnect it from the USB and see if I can programme the pic using the button on the programmer. Unless of course others have tried the same and killed their pic32. David M. |
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| Grogster Admin Group Joined: 31/12/2012 Location: New ZealandPosts: 9063 |
I was looking at the PICKit 3 for a while when I was CONSIDERING building my own MM clone from the ground-up. This has not been dropped as an idea, but it has been put on the back-burner for a while... I thought that the PICKit unit was quite pricey for what it is - that is another reason I decided not to buy it. It would be irrelevant price wise, if I had hundreds of chips to program, or thought that I would, but for one or two chips... This is when I decided I would just buy pre-programmed chips from Silicon Chip, if I ever get around to doing it at all. Being pre-programmed with a bootloader and a copy of the MM firmware, it is then easy to load new versions using just the USB cable. I think SC sell the pre-programmed 100-pin chip for about $18 or so. Smoke makes things work. When the smoke gets out, it stops! |
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| MOBI Guru Joined: 02/12/2012 Location: AustraliaPosts: 819 |
I agree, the PICKit3 is a bit expensive, but I got tired of writing a new programer routine in VB every time I changed to a bigger pic with different programming algorithms. Certainly, getting the chips pre programmed from CC is the way to go. At least the boot loader is not likely to change in the near future. I might have a go at doing the pic32 algorithm for my home grown programmer just for the hell of it once I get the grass roots MM going. David M. |
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| paceman Guru Joined: 07/10/2011 Location: AustraliaPosts: 1326 |
Hi David/Graeme, Yes, the SC pre-programmed chips are a good idea (and not bad value) but I wanted to learn how to do it all from the ground up - and now that I've got it anyway I'll embarrass myself if I don't get around to using it! When you look at the PicKit3 board it's pretty "busy" so maybe it's not too bad a price. Along with the new MPLab it's supposed to be able to do pretty much all their smaller PIC's too so if I ever got round to branching out to some "C" code or something (Hmm...) I could still program those. Greg |
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| Grogster Admin Group Joined: 31/12/2012 Location: New ZealandPosts: 9063 |
I'm not that familiar with the PICKit thingy, but MOBI mentioned above about loading the HEX file into the PICKit thingy, then you download from THAT to the PIC32 chip. Is that right? Seems an intreguing way to do things. Why not just stream the HEX file from the PC as the MM does? GRANTED, the MM(and others) have the bootloader installed, which is probably how they can talk to the USB and update from there in the FIRST place, whereas a totally blank PIC32 would not have this bootloader in place, so needs the PICKit to get you around that problem. Still, I would have thought that the PICKit just acts as the gobetween for the chip and the PC USB port, allowing the same kind of thing to happen. ...but I have not really read much about it, once I decided not to bother going down that path, and just let someone else build that bridge for me!(just buy pre-programmed chips) 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: 2288 |
are we talking about the $30 clone ones on ebay, with free delivery? auction number 350637699036 (just type the number into the ebay search box) |
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| MOBI Guru Joined: 02/12/2012 Location: AustraliaPosts: 819 |
There are two main ways to programme a pic - both use the programmer module (e.g Pickit3). 1. hook up the programmer to the PC usb and the 6 pin programming end to the appropriate pins on the pic to be programmed. Then load the hex file to be programmed into the MPLAB IDE or IPE. Then activate the programme function on the PC. 2. The other way is to download the hex file into the pickit3 device and take it (without the PC) to the field where you want to programme or update a pic. That is where the button on the pickit3 comes in. It makes it easy to take an update somewhere without having to cart a PC or laptop around. David M. |
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