max value eeprom

[filjoa]

Hi

What is max value which I can save on PIC18F252 EEPROM?

For example:

[dyeatman]

According to the latest manual on page 273 it says the following:

[FvM]

Handling of larger data types with EEPROM has been verbosely discussed at CCS Forum. Just search.

[filjoa]

hi

sorry I try find before post this topic and don't find anythink... I have write on search "eprom" and not "eeprom", sorry.

I make the new search and I find very information, and one of them tell to I see file "internal_eeprom.c" and on this file I see witch is possible read and write in 32bits.

[dnatechnical]

if you are using 18f252 then it has only 256 bytes eeprom
which addresss are 0 to 256 with data bit8

it can't save your data more then 256 bytes
if you r using external serial eeprom then its depend upon your select device

[filjoa]

why the "internal_eeprom.c" have write that?

when I can use this driver? this file is to external device?

[ckielstra]

The file internal_eeprom.c is for the internal EEPROM.
For external EEPROM see the file external_eeprom.c. This file calls the function read_ext_eeprom(), defined in the file for the specific external EEPROM. Examples are 2401.c, 2402.c, 9606.c, 24128.c, etc.

For storing an int16 you call write_int16_eeprom, a maximum value of 65536
For storing an int32 you call write_int32_eeprom, a maximum of 4 billion-something.

For larger values you can write your own function using the above example functions.

[dnatechnical]

"internal eeprom.c " file support to all devices which has internal eeprom.
Other devices has 256 or 512 or 1024 eeprom space. So address will be 16bit for higher than 256 bytes, but your selected device has 255 bytes only so when your address higher than 256 then it's overwrite to your 0 to 256 address as per your address.

[filjoa]

Hi

Ok I think which understand how this file work, thanks.

For example, if I have an array of 100000000 elements (+- 5 seconds at 20Mhz, of ADC reading, I think), is possible I save this on eeprom?

My idea is to read values from ADC in 5 seconds and save this on array, but if possible save this on eeprom.

Best regards

[arunb]

Hi,

You cannot save 100000000 elements (also bytes ??) in the internal eeprom of the mcu.

You could use an external eeprom for this, but these can be slow, I think you should use a Flash RAM for your application, they are fast and are meant for frequent write/erase cycles.

How many channels of the ADC are you going to access and save ?? Each sample of the ADC reading will consume 2 bytes or 16 bits, assuming the ADC has a resolution of 10 or 12 bits.

thanks
arunb

[ckielstra]

[filjoa]

hi

ok thank, my ideia is save sound like a eord for example. but I find on forum anda I read sometkins about isd4003, I'll try buy one and use them.

is possible compare sound with this IC on PIC? for example I record word "START" with my voice, on program I define is it word is call it activate one led. is possible?

best regards

[Ttelmah]

Not really....
You can't just compare a sound, like text. No two samples will be exactly the same. Even if you played the same sound, using a tape machine, and digitally recorded it twice, there _would_ be differences (timing, the random noise element in sampling, etc. etc,).
To compare sound, requires a huge amount of mathematics. What you do, is perform a Fourier analysis to work out the tones contained in the signal, and the relative levels of these, then use 'fuzzy logic' comparison, to see if the pattern of changes in the amplitude and levels is a good enough match to what you are looking for.
Do a search for 'Hidden Markov model', to find out about te basis used in most systems now.
You could perform this in a PIC, but on the standard PICs, perhaps expect to take several tens of seconds to perform the analysis, for even a single word. A DSPIC, could do it faster. However you are also looking at something involving several thousands of lines of quite sophisticated code. I was involved in writing a voice recognition system a few years ago (that is embedded on some cars today), and it was a nine month project, involving three programmers, and the core parts of the analysis were done in hardware to get the speed required. Something over 3 million gates, plus a processor with a lot more RAM, and ROM than the typical PIC....

Best Wishes

[filjoa]

thanks to the explanation Ttelmah

is possible buy one system voice recognizer to connect on PIC?

[Ttelmah]

Do a search for HM2007, VRP6679, and aP89341.
Generally limited vocabulary one or two chip solutions (some need a memory). The VRP, is rather old now, but has probably been replaced by something better. You will find people using them on many of the robotics forums.

Best Wishes