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Bilal
Joined: 24 Apr 2010 Posts: 75 Location: Islamabad
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4550 works with fat??? |
Posted: Mon Sep 26, 2011 9:02 am |
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hi.. i am working with PIC18F4550 + mmcsd.c + fat.c + ex_fat.c
But it can be able the create any file or do anything right.
I need to know am i using the right tools??
4550 is suitable for this purpose???
My compiler is 4.093
and i have updated fat.c and mmcsd.c according to some posts i have seen in this forum.
Kindly help me regarding this.
and sorry for my English.
best wishes _________________ ... |
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Ttelmah
Joined: 11 Mar 2010 Posts: 19360
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Posted: Mon Sep 26, 2011 9:16 am |
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Probably.
Big question, is how you are handling the voltage translations between the PIC, and the card?. This is the commonest source of problems. The 18F4550, operates down to 4.2v minimum, and level translators are needed between the card and the PIC.
Best Wishes |
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Bilal
Joined: 24 Apr 2010 Posts: 75 Location: Islamabad
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Posted: Mon Sep 26, 2011 9:35 am |
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I am using 3.3v for both controller and multimedia card.
Maybe I am wrong but I thought 18f4550 can perform at 3.3v.
Its datasheet said its (Wide operating voltage range) (2.0V to 5.5V).
And also mplab do program my chip on 3.3 volt. I am using PicKit3. _________________ ... |
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Ttelmah
Joined: 11 Mar 2010 Posts: 19360
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Posted: Mon Sep 26, 2011 9:48 am |
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You need the _LF_ variant to run below 4.2v.
Figures 28-1, and 28-2 in the data sheet.
Maximum 18.7MHz operation at 3.3v, with the LF version.
Best Wishes |
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Bilal
Joined: 24 Apr 2010 Posts: 75 Location: Islamabad
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Posted: Mon Sep 26, 2011 10:02 am |
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Thank you very much for your help.
Actually I am using 18F4550 with 3.3V and running at 48MHz.
It works fine with other features.
Only problem with "fat".
Maybe I need controller which is made to operate on 3.3V. _________________ ... |
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ckielstra
Joined: 18 Mar 2004 Posts: 3680 Location: The Netherlands
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Posted: Mon Sep 26, 2011 4:10 pm |
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I don't know the Microchip production process, but very likely the 'F' and 'LF' chips are just from the same production wafer where the better chips are selected to become 'LF' types and the others 'F'. If you are creating a hobby project and your chip is running at 3.3V then you might get away with it. For professional use you don't want to take this risk as the prototype might function and then when you order 10.000 more chips you would always see them fail (Murphy's 3'rd law).
The maximum of 48MHz is too high for 3.3V. You are now overclocking the chip at both a lower voltage than specified and at a higher frequency than specified. A bad combination. At least reduce the frequency to 18.7MHz maximum.
As mentioned before, in the SD-card projects most problems come from the 3.3V SD card to 5V PIC conversion. But since your PIC is running 3.3V this isn't for you to worry about.
Other possible problems:
- What memory card are you using? The CCS drivers are getting quiet old and were designed for the original SD-cards up to 4Gb. Newer SDHC-Cards will probably fail.
- You say you can not create a file? Are you creating the file using the CCS driver or on the PC? I don't remember exactly, but there was a problem doing it one way or the other. |
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temtronic
Joined: 01 Jul 2010 Posts: 9170 Location: Greensville,Ontario
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Posted: Mon Sep 26, 2011 4:37 pm |
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If you can switch over to USB 'flash drive' modules, you could use the Vinculum modules....$35..super easy to use.... |
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asmallri
Joined: 12 Aug 2004 Posts: 1634 Location: Perth, Australia
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Re: 4550 works with fat??? |
Posted: Mon Sep 26, 2011 4:53 pm |
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Bilal wrote: | hi.. i am working with PIC18F4550 + mmcsd.c + fat.c + ex_fat.c
But it can be able the create any file or do anything right.
I need to know am i using the right tools??
4550 is suitable for this purpose???
My compiler is 4.093
and i have updated fat.c and mmcsd.c according to some posts i have seen in this forum.
Kindly help me regarding this.
and sorry for my English.
best wishes |
If you want to be able to read and write to the SD card then the PIC18F4550 is not the best choice because of the limited amount of program and flash memory. SD/MMC write operations occur in 512 byte chunks requiring, as a minimum, at least one 512 block of RAM plus overhead. If you need to stay with the PIC18F family then variants like the PIC18F4620 would be better suited.
If you are comfortable with the PIC24 family then this would be an easier platform to work with delivering more RAM, Program Memory and no need to voltage level translation. _________________ Regards, Andrew
http://www.brushelectronics.com/software
Home of Ethernet, SD card and Encrypted Serial Bootloaders for PICs!! |
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Bilal
Joined: 24 Apr 2010 Posts: 75 Location: Islamabad
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Posted: Tue Sep 27, 2011 4:30 am |
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Quote: | - What memory card are you using? The CCS drivers are getting quiet old and were designed for the original SD-cards up to 4Gb. Newer SDHC-Cards will probably fail.
- You say you can not create a file? Are you creating the file using the CCS driver or on the PC? I don't remember exactly, but there was a problem doing it one way or the other. |
i am using 1GB MMC..
i cant able to creat a file with CCS driver (PIC)..
but it can show the directories on the root files correctly.. i have tested to make some files and directories by the PC..
but it cant able to open files (.txt files) and cant append also
and also i cant able to create new directory correctly.. (means it creates the directory but its corrupted) their filenames are "@" and some times " /" instead of the filename i have given to them..
i have modified the fat.c and mmcsd.c according to some posts found in this forum..
sorry for my bad English
Thanks _________________ ... |
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joseph20480
Joined: 21 Dec 2011 Posts: 42
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Posted: Thu Dec 22, 2011 2:39 am |
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Hi bilal !
Could you say me if you have found your bug... i try to do the same like you ... Sdcard with pic18f4550....But anything..
The compilation is ok, but any init, any file...
Thanks in advance |
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