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Forum Index : Microcontroller and PC projects : Growing a Maximite
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bigmik Guru  Joined: 20/06/2011 Location: AustraliaPosts: 2914 |
What about these ones Groggy? RS Components only 14c each upto 250 then 11c each and they have free postage still in AUS. I think these are the same 3.2mm x 1.6mm and ceramic devices. Regards, Mick Mick's uMite Stuff can be found >>> HERE (Kindly hosted by Dontronics) <<< |
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| MOBI Guru Joined: 02/12/2012 Location: AustraliaPosts: 819 |
I had a read through (part of) the PIC32 datasheet .PDF and it seems that once upon a time there was a ENVREG pin that could disable the built in 1.8 v regulator and allow an external supply of 1.8v on the VCAP pin. It looks like that has been done away with and now only a low ESR 10uF cap is used. "find" only found reference to the ENVREG being deleted. The quote is from the PIC32 data sheet. But I guess there are tantalums and there are tantrums?? David M. |
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Grogster Admin Group  Joined: 31/12/2012 Location: New ZealandPosts: 9308 |
@ bigmik - Yes, I am guessing they would be fine too.  I am buying at least 100 from Element14, so they only cost 9.8c each with that quantity. I am buying plenty of bits, so I get the international courier for free anyway, so... But thanks for the heads up - it is always nice to have options. 
@ MOBI - The PIC datasheet is a bit vague then. I'm going on what Geoff said about this, and he should know. Smoke makes things work. When the smoke gets out, it stops! |
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| MOBI Guru Joined: 02/12/2012 Location: AustraliaPosts: 819 |
That is an understatement. My pet hate is their long descriptions about the way things should happen instead of a simple step by step list preferably using example software. I think there are frustrated novelists among their technical department. David M. |
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| Grogster Admin Group Joined: 31/12/2012 Location: New ZealandPosts: 9308 |
Heh, heh, yeah, probably. 
I have always found Microchip PDF datasheets as a somewhat overdose of information, with the relevant information tucked in there somewhere....
Not that I am complaining, really - I am grateful that their datasheets are so comprehensive when others are not. Still, there is a lot of reading there, no matter what the device. I am pretty sure that one of the PICAXE chips(I think it was the one that RevEd based the 40X2 on) datasheets was more then 500 pages... Smoke makes things work. When the smoke gets out, it stops! |
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| MOBI Guru Joined: 02/12/2012 Location: AustraliaPosts: 819 |
HI, Downwind made me a tool for locating SMD devices to facilitate easier soldering. He doesn't remember posting a picture of the tool. I found it wonderful for holding the PIC32 in place while I soldered it. The curved lever allows one brass pin to be lifted before the other so that the back pin can hold the PCB still whilst positioning and then pinning component. It is brilliant. In the back ground is the jaws of a PCB holder vise that allows the board to be flipped over. 
David M. |
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MicroBlocks Guru Joined: 12/05/2012 Location: ThailandPosts: 2209 |
Here are my schematics of the small pic32 board. I would welcome feedback and error spotting. It also contains tables summing all the possible pin uses. My first project using Diptrace, it went pretty smooth. The design has many uses in mind and can be hooked up in different ways. With female connectors it can be used for prototyping. For production it can be put on a 'motherboard', use a backplane when lots of circuitry has to be controlled, a board can be piggy backed (this will be my way of mankig it MM compatible), or pigy back a small CAN and LCD module, or a GPS module etc... The goal is to make the step from prototyping to final product very smooth as you can use the same part for both. In the minimal form it should already be able to run MMBasic and use it through the USB with a terminal. After error spotting this will be send of to make some prototype pcb's, if someone wants want to help me test it, i would be glad for the help and send you one. (Printing to a pdf has some label offset problem. Not able to fix that, probably need another, i use bullzip pdf printer now. No such problems with a real printer.) 2013-01-28_073903_DipTrace_Schematic_-_TZBlox-CPU_32_rev_C.d ch.pdf Size of the board is 50mm x 49mm. front: 
Back: 
Microblocks. Build with logic. |
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| MOBI Guru Joined: 02/12/2012 Location: AustraliaPosts: 819 |
I wouldn't mind helping you test it and bear any costs you may incur as a result. I like the design and about the same size as my breakout board too but with all the power & reset chips etc. If you do a parts list, I think that C1 (10uF) needs to be specified as tantalum or similar low ESR (1ohm). David M. |
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| MicroBlocks Guru Joined: 12/05/2012 Location: ThailandPosts: 2209 |
I am waiting to get all of the parts used to be able to finalize the pcb design. Sometimes certain smd sizes are hard to get, so i am trying to source the most common sizes. Especially C1's pads can change if i need a bigger footprint. Microblocks. Build with logic. |
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| MOBI Guru Joined: 02/12/2012 Location: AustraliaPosts: 819 |
It is a pity (?) that the components (other than chips) can't be standard "through hole" as not too many people have a good supply of smd resistors/caps etc but like me, have a drawer full of components with leads. My eyesight is a bit lacking when it comes to reading some of the smd labels. David M. |
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| Grogster Admin Group Joined: 31/12/2012 Location: New ZealandPosts: 9308 |
SMD caps are not marked at all - the ceramic ones anyway. VITAL that you file them at the time you get them, as all being the same size, if you don't, they could be any value.
I'm impressed with the board from TZAdvantage. 
Are these going to be supplied assembled, or blank PCB only? If they are assembled - sorry - POPULATED, then I may well be interested in some too, as this would save me having to build my own one, which was on my to-do pile... Smoke makes things work. When the smoke gets out, it stops! |
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| MicroBlocks Guru Joined: 12/05/2012 Location: ThailandPosts: 2209 |
According to Geoff's site: It must be a low ESR Tantalum capacitor or a 10uF ceramic SMD capacitor between the solder pads for C5 (or C3). The best fix is to use a 10μF 16V Ceramic with a X5R dielectric. A 10μF 16V Ceramic X5R is 1210 size and a 6.3v one is 0603. A 1210 is close to impossible to put on the board, a 0603 is what i currently use. Would there be a big difference between a 16v and a 6.3v version? The ESR on X5R dielectric should be lower then 1, even mbetter then tantalum. Is ESR the most critical or other characteristics? I am trying to source a few of those, but mainly here it is sold on a reel, and that means 4000 pieces. Microblocks. Build with logic. |
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| Grogster Admin Group Joined: 31/12/2012 Location: New ZealandPosts: 9308 |
Just tried to check out TZBLOX.COM, but I hear it is reserved.....
Just go to that website and you will see what I mean.  Smoke makes things work. When the smoke gets out, it stops! |
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| Grogster Admin Group Joined: 31/12/2012 Location: New ZealandPosts: 9308 |
No difference in capacitence between the two, but the breakdown voltage is the thing. According to the Microchip PDF and comments by MOBI, this needs to have a voltage rating of at least 6v, so 6.3v should be safe, and was the one I would choose over the 16v one. Can you not order from Element14 - there are stores in Australia, England and the United States - you can order as many or as few as you want, of any type you want, therefore not requiring the purchase of reels of parts... Smoke makes things work. When the smoke gets out, it stops! |
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| MicroBlocks Guru Joined: 12/05/2012 Location: ThailandPosts: 2209 |
Luckily it is me that reserved it.
Still trying to find some decent webshop software that combines good with a blog/forum, asp.net is a must. This pcb will be the first, followed swiftly by a add-on board to make a color Maximite. Color composite is also in the works, but i am not there yet. A GPS module, OLED/LCD etc are also ready to go from proto to pcb layout. Together with other stuff like switches, headers, leds, etc it would hopefully interest people. Another important part, to actually honour the name of the site is to have 'blox'. This will make prototyping even easier as everything is contained in a small box. A 3d printer is on its way to make prototypes for that. The higher voltage ones often have lower ESR, but i am certain the X5R is low enough. Ordering single parts is not always possible. Some have different suppliers. I need my supplier/importer to be in Thailand otherwise i have to pay rather high import rates, and i am not a big enough company to hold office in a free trade zone. I just need to do some legwork to find one locally, samples should be possible. I will populate the boards myself first. Already have some contacts that can do the pcb/populting for me, but that is only interesting when i need more thern about 50 pieces. Hopefully the final pcb will fit on a 10x10 cm board. That size will hold the MCU board, a MM board, Frontpanel and mini backplane. Will be tight. Microblocks. Build with logic. |
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| Grogster Admin Group Joined: 31/12/2012 Location: New ZealandPosts: 9308 |
Re: ordering parts - Okey dokey - I understand.
I have that problem(import taxes) on larger orders, so I know what you mean. Luckily for me, most of my international orders are below the threshold when I have to pay import duty.
So I can assume that your CPU board thing as detailed above, is a populated board - not one you have to assemble a-la' a kit? Assuming that it IS populated, will you be supplying boards with the PIC32 blank, or with a copy of the maximite firmware on it? EDIT: YAY! 100 posts today!!!  Smoke makes things work. When the smoke gets out, it stops! |
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| MicroBlocks Guru Joined: 12/05/2012 Location: ThailandPosts: 2209 |
After a mail from Geoff some time ago i changed the pcb to be compatible with the maximite firmware. The remark that it is much more difficult to maintain versions is a very good one and i made the board more generic and moved all the maximite specifics to an add-on. It will still allow other uses of the pic32 board. As the maximite firmware will be the one i will test it with, my wish is to deliver them as a kit or fully assembled. I am not sure about the distribution rights for the firmware, i will contact Geoff before i can make any promises. Microblocks. Build with logic. |
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| paceman Guru Joined: 07/10/2011 Location: AustraliaPosts: 1329 |
MOBI/Grogster, I've got 30 of these Murata 10uF I got a few months ago from Rockby and plan to use with the PIC32's. I'm not sure how good an ESR they have and I haven't tried them yet, but they're 1206 size, 10uF, 10%, 16V versions and use K7R dielectric if that's any help. Rather than Grogster having to re-send from NZ when he gets his I'd be happy to post you a few gratis if you PM me your address. BTW the ones Mick mentioned from RS are shown on their site as currently out of stock. Greg |
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| bigmik Guru Joined: 20/06/2011 Location: AustraliaPosts: 2914 |
Gday TZ, Try DoPDF from Dopdf.com Regards Mick Mick's uMite Stuff can be found >>> HERE (Kindly hosted by Dontronics) <<< |
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| robert.rozee Guru Joined: 31/12/2012 Location: New ZealandPosts: 2350 |
nice bit of layout, but a few suggestions: 1. place all the pin headers on a 0.1" grid, so the board can be attached down to veroboard or similar and have all the pins line up. that is one of my main complaints with the arduino, where one of the headers is off-grid; 2. i'd up the footprint of the 10uF ceramics if you can, it is always easy to solder a smaller package onto a bigger footprint, but not vice versa; 3. provide thermal relief around all component leads and header pins that connect to any ground or supply planes. as it stands, you'll find pins on headers that are connected to ground quite difficult to solder, and even more difficult to unsolder. "thermal relief" means keeping the pad isolated from the surrounding plane, and connecting to the plane with just a cross of 25 mil tracks. similarly with the SMD capacitors, which will be quite difficult to solder otherwise. the only exception is the tab of the 3v3 regulator, where you want good thermal transfer. |
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