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crukid88
Joined: 04 Oct 2007
Posts: 14
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| MMC Database project using PIC16 or PIC18,possible? |
 Posted: Thu Oct 11, 2007 7:29 am |
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Good day to all!
I need your advice. I am planning to make a stand alone system that has a database of the RFID. Its some kind of a automated attendance system. I want to retrieve and append date,time and other data altogether. It will take approximately 100bytes. I want to put the records on the same .txt file and a directory of the particular student. Is this possible?if yes what are the requirements? |
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jecottrell
Joined: 16 Jan 2005
Posts: 559
Location: Tucson, AZ
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| Posted: Thu Oct 11, 2007 10:59 am |
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Yes.
You need a PIC that has a healthy amount of RAM for the FAT implementation. The 18F4620 has worked well for me.
Use either SD or Micro-SD cards. (Mini SD are hard to find.)
I use a FAT library available from one of the members here. It is inexpensive, relatively easy to port. Search google for Brush Electronics or this forum for asmallri.
John |
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ckielstra
Joined: 18 Mar 2004
Posts: 3680
Location: The Netherlands
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| Posted: Thu Oct 11, 2007 1:53 pm |
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| Quote: | | You need a PIC that has a healthy amount of RAM for the FAT implementation. The 18F4620 has worked well for me. |
As an additional note: 'healthy' means minimal 512 bytes, the size of the MMC/SD card block write size, and then some extra for your program itself. This rules out all PIC16 processors.
| Quote: | | Use either SD or Micro-SD cards. (Mini SD are hard to find.) |
What is wrong with the MMC cards? |
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jecottrell
Joined: 16 Jan 2005
Posts: 559
Location: Tucson, AZ
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| Posted: Thu Oct 11, 2007 1:59 pm |
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| ckielstra wrote: | | What is wrong with the MMC cards? |
Sorry, I didn't qualify that. I've defaulted to SD cards because of availability. It seems that MMC are becoming harder to come by. They are all easy to get online, but I will typically need to 'run out and pick one up' and the latest/greatest format is always easier to find. |
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crukid88
Joined: 04 Oct 2007
Posts: 14
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| Posted: Thu Oct 11, 2007 6:01 pm |
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would it be fast,for example I have 300 files or users.
I am having problems on how to store the files in the SD so that the PIC18 can access it. Any advice on this? |
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asmallri
Joined: 12 Aug 2004
Posts: 1634
Location: Perth, Australia
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| Posted: Thu Oct 11, 2007 11:17 pm |
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If you implement a FAT file system then you can read the card on a PC or PDA using a standard card reader. If you implement your own file system they you need to write you own PC application to interpret the file system.
Fast is a relative term and depends on many factors. A typical implementation should be able to read or write data at the rate of 1K to 100K bytes per second depending on how the application is written, how fragmented the media is and the amount of file opening and closing. If you are using a FAT file system then you can store thousands of files.
_________________
Regards, Andrew
http://www.brushelectronics.com/software
Home of Ethernet, SD card and Encrypted Serial Bootloaders for PICs!! |
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crukid88
Joined: 04 Oct 2007
Posts: 14
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| Posted: Fri Oct 12, 2007 1:31 am |
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| to asmallri: I saw your website and you sell a library. I would just like to ask. What is the difference between your library and the driver included in CCS? |
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asmallri
Joined: 12 Aug 2004
Posts: 1634
Location: Perth, Australia
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| Posted: Fri Oct 12, 2007 8:06 am |
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My library includes a full data logger application demonstrating real time acquisition and logging of a data stream to SD/MMC cards. It also supports FAT12/16/32. I have a lot of CCS customers so I guess there must be something I do well :-)
_________________
Regards, Andrew
http://www.brushelectronics.com/software
Home of Ethernet, SD card and Encrypted Serial Bootloaders for PICs!! |
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