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Forum Index : Microcontroller and PC projects : CONCEPT - FAT-mite 1A...
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Grogster Admin Group  Joined: 31/12/2012 Location: New ZealandPosts: 9586 |
Hi folks. I see a few posts from people here from time to time wanting logging and/or file support for the MicroMite series of chips. This has made me think. The thought struck me that I could design a PCB that combined the VideoMite PCB with the ALFAT SD card module. This SD module would probably be hooked up via the I2C, just because I2C supports multiple devices, so it would not gobble up the whole port like it would if connected to a COM port or SPI. This would essentially give the existing VideoMite board and MicroMite chip, access to an SD card with full FAT/FAT32 filesystem support and long-filenames. People wanting more technical info on the ARM processor at the heart of the ALFAT module, can follow this link. Is this something that people would be interested in? If so, I could start designing a layout. It would be very easy, as I would use the existing VideoMite pattern, and build on that to get the ALFAT module in. Naturally, the PCB would be bigger to accommodate the ALFAT footprint, but other then that, it would be easy to build for anyone, as the VideoMite uses all through-hole parts. I realise that you could just add the module yourself to any existing uM circuit, but it would be nice and neat if all on one board. THE OTHER OPTION is to integrate the OpenLOG unit. which is much smaller, so would make the PCB smaller too, but it does not have the advanced filesystem support of the ALFAT module. However, OpenLOG is open, so we could use a DIL version of the chip on that module(if one can be had - I will have to find out), and thus make the entire thing easy to build with no SMD for people to worry about. Thoughts? Opinions? Smoke makes things work. When the smoke gets out, it stops! |
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panky Guru  Joined: 02/10/2012 Location: AustraliaPosts: 1114 |
Hi Grogster, Would a rework of the original Maximite be an alternative to trim down size to the minimum? Alternatively, if the 470 road is followed, that seems to have the option of replacing the original Maximite feature wise (sd card support, 12k boot space, video etc.) but still offer the potential of code compatibility with the umite? Cheers, Doug. PS. This should prove cheaper and simpler than adding another chip to do sd card? ... almost all of the Maximites, the MicromMites, the MM Extremes, the ArmMites, the PicoMite and loving it! |
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| micronut Newbie  Joined: 03/09/2014 Location: United StatesPosts: 37 |
Grogster, that is an interesting idea. I have a discontinued FEZ Domino which is a C# .NET processor with a similar SD interface which I've thought of using in the way you mentioned. I see two good points in using the ALFAT 1. It uses the proprietary 4 bit SD interface rather than SPI so it would be much faster transferring data. 2. It requires less hardware and software resources than having it on the PIC chip. A 2 line serial and a small amount of coding is all that is needed to get it running. |
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Oldbitcollector Senior Member  Joined: 16/05/2014 Location: United StatesPosts: 172 |
Essentially, I did the same thing using a Propeller as the chip to run the SD card. (As well as keyboard and video) I'd love to see a second Micromite used to control file storage. I'm betting it would probably work and be an inexpensive solution. (Micromite, cap, a few pull resistors, and an SD socket) My Propeller/Micromite mini-computer project. |
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| robert.rozee Guru Joined: 31/12/2012 Location: New ZealandPosts: 2428 |
i've been thinking for a while about the usefulness of a colour maximite "core board", built high-density using SMD resistors and capacitors to reduce size, and containing: 32MX695/795 processor RTC + battery 3v3 power supply video mixing components sound mixing components this would then have 0.1" single-row connectors around the sides for SD card (perhaps following the pin order used for the cheap SD daughterboards available on ebay), keyboard, video, ICSP, 5v in, etc. the 2x i/o headers could consist of a 90 degree header for the main one and a 2-row 0.1" header for the arduino pins. or, build the whole lot within an arduino footprint, with the main i/o header sitting above the top row of arduino pins. by keeping the 12v -> 5v section offboard, the builder is free to use a switchmode module, or 5v power from an existing source. the main idea is to produce something that is CHEAP (costing little more than the PCB + processor), which can easily be turned into a full colour maximite with just the addition of a bit of wiring. or kept minimal as an embedded device. the big killer with the colour maximite, in my view, has always been that all the versions available are relatively expensive. addendum: what is the cost of 2 micromites versus the cost of a 32MX695? rob :-) |
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| Grogster Admin Group Joined: 31/12/2012 Location: New ZealandPosts: 9586 |
Thanks for the feedback, guys - keep it coming please. 
ALFAT is relatively expensive, but it is a very advanced module. OpenLOG is open and mildy expensive, but not as advanced as ALFAT. I like the idea of using a MM as a dedicated SD card controller - would keep costs right down, but in some ways, why re-invent the wheel? I guess the cost saving of having a MM drive an SD card for storage is worth it, but the time that would be required to get it working reliably vs just using something like the OpenLOG or ALFAT right out of the box... I have both the OpenLOG and ALFAT modules here, so I suppose I could hook the ALFAT up to the MM and have a play around first. EDIT: @ Rob - The UBW32 is pretty much what you are talking about, but it is not as cheap as you are wanting. Last time I looked, the 795's used in the CMM were about $17 each, vs $4 or so each for the 170 MM chips. Smoke makes things work. When the smoke gets out, it stops! |
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| Oldbitcollector Senior Member Joined: 16/05/2014 Location: United StatesPosts: 172 |
I've been playing with a breadboard version of this... http://www.hobbytronics.co.uk/usb-host-flash-drive It works, but the code isn't open source.. Seeing it in action makes me believe that an SD version of this should be more than possible with the MM. My Propeller/Micromite mini-computer project. |
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| Grogster Admin Group Joined: 31/12/2012 Location: New ZealandPosts: 9586 |
UPDATE: Yep, you can get the OpenLOG controller in DIP format for NZ$4.84 each from element14. This would allow you to build an OpenLOG using a full-size DIL chip for easy construction. This chip, and SD card holder and a few passives, and you could add this to a MM for about US$10, I would think. It now just comes down to choosing between OpenLOG and ALFAT, and if this project is even worth the effort at all. I'm not sure what is needed to program ATmega chips, but with any luck, the programmer software is free, but they may be a programmer device that is needed, which would screw with the price. The OpenLOG device has the advantage that we could hook it to COM2, leaving COM1 for any fast comms needed. Not really viable, if you are already using both COM ports on the MM though. Smoke makes things work. When the smoke gets out, it stops! |
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| Oldbitcollector Senior Member Joined: 16/05/2014 Location: United StatesPosts: 172 |
@Grogster, Could you post a link... My Google'Fu skills are failing tonight. I'm attempting too see if Element14 on this side of the pond might have them as well. Thanks My Propeller/Micromite mini-computer project. |
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| Grogster Admin Group Joined: 31/12/2012 Location: New ZealandPosts: 9586 |
UPDATE: Programming ATmega chips appears to be very painless. Here is a link to a nice easy programmer for the serial port, and a programming software to get the HEX file into your ATmega chip. Looks quite easy. (where have I heard that before!) @ oldbitcollector: Here is a link to the DIP version of the chip used in the OpenLOG unit - very reasonably priced. Smoke makes things work. When the smoke gets out, it stops! |
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| viscomjim Guru Joined: 08/01/2014 Location: United StatesPosts: 925 |
you could always add another "software serial port" using some of Peter's code... |
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| Oldbitcollector Senior Member Joined: 16/05/2014 Location: United StatesPosts: 172 |
Ah ha! That's the ticket. I'm seeing $3.24 for singles from my supplier (mouser) here ($2.65/10) That looks like an extremely reasonable solution.. Looking for the hitch.. ;) My Propeller/Micromite mini-computer project. |
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| Oldbitcollector Senior Member Joined: 16/05/2014 Location: United StatesPosts: 172 |
I'm no Arduino expert, but I do have a very dusty UNO here with a ATMEGA328P-PU chip in it. Couldn't the UNO be used as a cheap programming device? My Propeller/Micromite mini-computer project. |
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| panky Guru Joined: 02/10/2012 Location: AustraliaPosts: 1114 |
I really like this idea of Rob's - surely if cost is an issue, this would work out cheaper than any 2 chip solution? The daughterboard could be naked and populated to suit ones purposes? Doug. ... almost all of the Maximites, the MicromMites, the MM Extremes, the ArmMites, the PicoMite and loving it! |
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| Grogster Admin Group Joined: 31/12/2012 Location: New ZealandPosts: 9586 |
Yeah, but isn't the UBW32 or MiniMite exactly that? EDIT: On cost: 1x PIC32MX170 MicroMite chip - US$4.03 each (plus freight) 1x ATMEGA328 for OpenLOG - US$3.24 each (plus freight) TOTAL = US$7.27 1x PIC32MX795F512 - US$9.87 (plus freight) Two-chip method is still US$2.60 cheaper before you do anything else.  Smoke makes things work. When the smoke gets out, it stops! |
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| panky Guru Joined: 02/10/2012 Location: AustraliaPosts: 1114 |
All true Grogs but I was also thinking of the code maintenance side of things and the headaches that causes Geoff. For the sake of a few bucks I would rather have the same (or at least VERY similar) interpreter across all platforms for interoperability. Just my thoughts mate, 
Cheers, Doug. ... almost all of the Maximites, the MicromMites, the MM Extremes, the ArmMites, the PicoMite and loving it! |
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| Grogster Admin Group Joined: 31/12/2012 Location: New ZealandPosts: 9586 |
Hmmmmm - fair comment. So many things to design, so little time.   Smoke makes things work. When the smoke gets out, it stops! |
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| JohnS Guru Joined: 18/11/2011 Location: United KingdomPosts: 4034 |
I couldn't find enough info there. Any idea what actual ARM chip it is? It looks terribly expensive. About the same as the RPi! (Which would be overkill.) Seems sad to recommend Atmega/Arduino or an STM32 but I think both are far cheaper and will do. John |
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| Grogster Admin Group Joined: 31/12/2012 Location: New ZealandPosts: 9586 |
Yeah, the ALFAT is about US$30 a module - pretty heck-spensive. I am thinking more and more towards an open-log thing. As OpenLOG is "Open", I am thinking about designing a clone of it, which could be offered up here for members to build. It would be exactly the same as the commercial OpenLOG sold by Sparkfun, but it would only cost half as much to make - about US$10, I would think. I would use a full-size SD card socket, for easy soldering, and that would be the only SMD part. How about that idea? Smoke makes things work. When the smoke gets out, it stops! |
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| micronut Newbie Joined: 03/09/2014 Location: United StatesPosts: 37 |
Grogster, could you cut the cost of the ALFAT by just getting the chip ALFAT Chip ? That way it'll be $13.95 US. Still pricier than the other options but not as bad. |
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