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Robson
- 6th August 2007, 01:49
Hello,
in my next project i want to store data via a RS232 connection. The procedure is very simple, but i donīt know which pic to use.
While receiving data they should be stored but the most internal EEpromīs are really small.
What i need is RX TX and a buffer that will not erase the stored data after disconnection.
Also i want to use a LCD to show parts of the received data.
Can anyone help me how to realize that and which PIC is good for my project?
Thanks a lot

Robson
GrandPa
- 6th August 2007, 05:34
Since you will not be able to find any PIC with more than 1k data EEPROM,
I would suggest you to go with an external 32k 24LC32 EEPROM. This need only two wire, one for clock (SCL pin) and one for data (SDA pin). Can go as fast as 400khz and it's very easy to set up an program with PBP. This left you with plenty of pins availables for the LCD.


J-P
Jerson
- 6th August 2007, 05:49
The 24C32 can hold only 32kilo bits or 4 kilo bytes of data. You may need to consider the 24C512 that holds upto 64Kilo bytes of data.

Jerson
Robson
- 6th August 2007, 10:02
Thanks for fast reply,
but howīs about the timing speed with serial eepromīs? After a byte is written i need to include a waitstate of 10ms or not?
If iīm using a 4 MHz osc and a baudrate of 9600 up to 19200 is it possible to realize that or is the waitstate after each write not necessary?
Which kind of i2c eeproms are available > 32kbytes, and speed?
Note : The reading data should be stored on the fly !

Robson
Ioannis
- 6th August 2007, 11:38
For the normal EEPROM, yes, you have to wait the 10ms. Better idea is to make page write according to the chip datasheet that you will select. You may write 32 or 64 bytes at once (that is 10ms...).

If you do not want any delay then look at www.ramtron.com

Ioannis
Jerson
- 6th August 2007, 14:52
Your application looks like its going to keep updating the memory continuously. Flash memories (24Cxxx series) have a finite lifetime and can waste away in this kind of an application. FRAM based memories are the ideal choice for you.

Jerson
Robson
- 6th August 2007, 22:15
Your application looks like its going to keep updating the memory continuously. Flash memories (24Cxxx series) have a finite lifetime and can waste away in this kind of an application. FRAM based memories are the ideal choice for you.

Jerson

Itīs not necessary to update the data continuosly. Only need to change some bytes and rewrite the bytes at their location.
To delete the device itīs needed to delete by myself.
Maybe i should explain more about my project. Itīs still working in my head ;-)
I want to save data from an incoming RS232 Port of a printer.
At first, the printer send a command, which activate my PIC.
Now the Pic is receiving a command from the printer. Then the PIC must send a command like "ready to receiving data".
Now the printer sends data to the PIC. These received data should be predefined e.g. 4kbyte,8kbyte or 16kbyte lenght. I donīt know how long is the receiving data, but maybe in this range. Now the PIC should store the received data at an eeprom or flash in this lenght which was predefined before (4k,8k, or 16k).
Now when the bytes are stored i have to get access to the stored bytes to change some parameters and save it back on the storage device.
If iīm using a 128kbyte eeprom and my stored data of the first received data is e.g. 8kbyte long, then the next block should be saved at the end of the last block.
Now i will have space to save 17 blocks in that eeprom.
On a second eeprom (smaller) should only be store the changed parameters and the serial of the printer. The changed paramaters are usually about 32 bytes/block.

Thank you for any advise and help.
(I hope my english is good enough for you to understand me)

Robson
BobK
- 6th August 2007, 23:10
Hello Robson,

Why don't you get yourself a flash card with a RS232 adaptor. There's a site out there that sells these units. I don't have the information right now but I'll look for it later this evening and get back to you. The board has its own micro to handle the overhead. It just might be what you are looking for.


BobK
Robson
- 6th August 2007, 23:16
Whatīs about programming the card? Of course such a solution is possible too. However i only need a storage device which communicate with my picbasicpro.
When you found the site please forward it to me thx

Robson
BobK
- 7th August 2007, 15:34
Hi Robson,

Goto www.compsys1.com and look for their MMC/SD setup on the Microcontroller projects page. This should take care of your needs.

BobK