Additional Memory

[krismoly]

Hi Folks,

I'm new to pics.

I have a number of projects in mind that require some sort of portable memory. (two Identical units, and the memory will be transferred between the two units).

I have thought of using usb memory sticks....but have been advised that this would be extremely difficult.

I need approximately 1mb, (it will only be used for storing ascii txt.) a possible solution is to use sd memory cards.

I dont have a clue were to start! So any links, advice, or ideas would be extrememly welcomed.

Kind Regards
Kris

 

[eblc1388]

Using an I2C serial eeprom 24C1024?

Example of I2C memory access is easily available from the web and it is easy to bit-bang it on PIC that does not have dedicated I2C interface pins.

 

[krismoly]

Thanks for that eblc1388.

Is the 24c1024 a chip or a memory card?

If it is a chip then it is not suitable because it would be to cumbersome to keep swopping the chip between units.

Regards
Kris

 

[Sceadwian]

Use an SD/MMC card. The interface is 3.3volts serial and can be read from virtually any micro controller. You can get them in sizes upwards of 2 gig, and they're dirt cheap. Do a google search you should be able to find a TON of information on the protocol. Digikey sells sockets for them. Or you can homebrew them, the form factor is simple.

 

[Nigel Goodwin]

Use an SD/MMC card. The interface is 3.3volts serial and can be read from virtually any micro controller. You can get them in sizes upwards of 2 gig, and they're dirt cheap. Do a google search you should be able to find a TON of information on the protocol. Digikey sells sockets for them. Or you can homebrew them, the form factor is simple.

EPE also have a currently running series about interfacing them to PIC's.

 

[eblc1388]

Is the 24c1024 a chip or a memory card?

If it is a chip then it is not suitable because it would be to cumbersome to keep swopping the chip between units.

Regards
Kris

Yes, it is a 8-pin DIP. You'll need a 5-pin connector to connect it to a board.

If you like to go the SD/MMC route, please get some more information at Wiki about its features first, as it is a closed standard.

I might be wrong but it appears to me that using SD/MMC is about as difficult as to read/write an USB memory device. One would need quite a bit of PIC memory to implement such routines. If you found any additional open source information or links on interfacing them using PIC ASM codes, please post them here.

 

[Nigel Goodwin]

I might be wrong but it appears to me that using SD/MMC is about as difficult as to read/write an USB memory device. One would need quite a bit of PIC memory to implement such routines. If you found any additional open source information or links on interfacing them using PIC ASM codes, please post them here.

Like I said above - read EPE, tells you everything you need to know, and gives the source code as well.

Essentially there are two methods, a simple write to memory, and a method that maintains PC compatibility - so you can read the card in a PC.

 

[eblc1388]

Though I have not subscribed to the EPE magazine, the source file on what Nigel described above is available for download on the EPE UK website. It is under the PIC "Pick n Mix" section inside the Download area, date December 2006.

EPE Download Area

I have downloaded it and have a look and it is quite involved.

For the specification of SD I/O requirement, one can get the simplified (or full version if you have US $1000 to burn in your pocket) version in pdf here.

simplified version of the SD 1.0 specification