My project!!!!Please HElp

[pulvirenti]

Posted on November 30, 2007 at 07:58

My project!!!!Please HElp

[pulvirenti]

Posted on November 28, 2007 at 08:32

Hello friends, my project is aquire data from sensors, it's a data logger.

I want to store all data in a SD card so to solve communication with PC and limited memory problem. My st72334 has SPI interface to comm with SD card. i have a problem, my st has not I2C bus, so I have to use an external FRAM or E2PROM working in SPI. I need EEPROM because Sd want 512 byte EEPROM. I'm going to use a master- 2 slave configuration.Is my project possible? I want to store first data in EEPROM (up to 512) and then pass them in SD card. To make working SD card in windows I have to initialize Sd with FAT16 format. Could anyone help me to write in assembly a code to format from MCU SD card? Is possible what I propone? All opinions are wellcome Thanks

[fggnrc]

Posted on November 29, 2007 at 04:02

Salvatore,

there are some ST7 with a I2C controller, if you need this bus. In my opinion, your project is feasible if you choose the right microcontroller. Some ST7 have some EEPROM on chip, so there is no need to use an external one. I think that the hardest thing is the FAT16 implementation. The code that implements this task may be big and difficult to store in the microcontroller memory, so I suggest you to choose at least a ST72325K6 which has SPI, SCI, I2C, 1024 bytes of ram and 32Kbytes for code. Ciao EtaPhi

[pulvirenti]

Posted on November 29, 2007 at 09:28

I have requested st2325 as sample and I received. My only problem is that I have a dedicated evaluation board of Softec for st2334 that not have I2C bus and it has a little eeprom 256 byte. Sd wants 512 byte at a time so the need of an external eeprom! The second problem is that ST is not programmable with a high level language as Basic, so I'm thinking to pass to Pic family.

Any suggest EtaPhi?

[fggnrc]

Posted on November 29, 2007 at 09:58

Salvatore,

you can use 512 bytes of ram as a buffer for the SD card. You therefore do not need any EEPROM at all! The remaining 512 bytes can be used for the firmware and the stack, and this is a lot of ram... ST7 micros can be programmed in C (not in Basic as the PICs) and the C compiler is free if the code size is less than 16K. Your application needs to manage a large buffer (related to the microcontroller capabilities). The lower-end of the PIC family (the cheapest and the ones that an hobbyst uses, I mean) has difficulties to manage such a buffer, so you can have to split (and manage) this buffer in smaller pieces. This adds code complexity (i.e. bigger code size) and bugs, so reserve the complexity to the FAT16 management and not to the trivial housekeeping tasks... Ciao EtaPhi

[pulvirenti]

Posted on November 29, 2007 at 14:54

So u suggest me to use St7 for this use or to abort project?

[fggnrc]

Posted on November 30, 2007 at 03:55

Salvatore,

a microcontroller is a tool to make your project. ST or nothing, is not the right answer. If your project is worth your efforts, a tool have not to stop you! My advice is to examine and plan the project requirements. The coding phase will follow. Do not code the details, but focus your attention to the SD memory, the FAT16 filesystem and the communication and interaction with the user. If you can't find the way to access the SD memory or to handle FAT16, there is an option to buy some code to integrate in your project. This option is usually available to the commercial projects, but it can help the project to complete successfully. Ciao EtaPhi

[pulvirenti]

Posted on November 30, 2007 at 05:06

How can I buy this code and where overall?Thanks for help EtaPhi

[fggnrc]

Posted on November 30, 2007 at 06:46

After a quick search on the net I found the page:

''FlashFile SD/MMC FAT12/16 File System Source Code Solution'' For about $200, they give you the C source code for an Atmel microcontroller. I found also a free source code for the PIC, so the choices seems to be many... Good luck for your project! EtaPhi

[pulvirenti]

Posted on November 30, 2007 at 07:17

Can u give me link where I can take free source? I saw pay website and it's too expensive!!!

Thanks