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ELCouz
Joined: 18 Jul 2007
Posts: 427
Location: Montreal,Quebec
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| EEPROM 8-bit or 16-bit? |
 Posted: Wed Apr 08, 2015 3:37 pm |
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I've been trying devices in the 24-bit opcode world...
On the 30F6014A, I have access to 4K of internal EEPROM.
I'm writing a function to write and read unsigned int32 directly to the EEPROM.
However from the CCS help file it's not very clear what type of int I expect to receive.
| Quote: |
Relevant Functions:
(8 bit or 16 bit depending on the device)
read_eeprom(address)
Reads the data EEPROM memory location
write_eeprom(address, value)
Erases and writes value to data EEPROM location address.
read_eeprom(address, [N])
Reads N bytes of data EEPROM starting at memory location address. The maximum return size is int64.
read_eeprom(address, [variable])
Reads from EEPROM to fill variable starting at address
read_eeprom(address, pointer, N)
Reads N bytes, starting at address, to pointer
write_eeprom(address, value)
Writes value to EEPROM address
write_eeprom(address, pointer, N)
Writes N bytes to address from pointer
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Microchip datasheet talk about transferring data per chunk of words (so int16 right?)
I've always dealt with writes one byte at time on the PIC16/18 series.
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Regards,
Laurent
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Here's my first visual theme for the CCS C Compiler. Enjoy! |
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asmboy
Joined: 20 Nov 2007
Posts: 2128
Location: albany ny
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| Posted: Wed Apr 08, 2015 5:38 pm |
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although the 30F part in question can allow values less than 16 bits - for the purposes of the data sheet, a WORD for the EEPROM is still 16 bits ....
So what do you think when you read page 57 of the datasheet? |
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bkamen
Joined: 07 Jan 2004
Posts: 1615
Location: Central Illinois, USA
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| Posted: Wed Apr 08, 2015 10:29 pm |
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Ultimately, it comes down to the datasize of the storage medium.
YES, you are still writing bytes.
One method I like it to put my entire config into a structure.
This can be a mix of anything. uint8, int16, floats, doesn't matter.
then I create a pointer to the structure when saving and step through the bytes of the struct and save/load them to/from the EEPROM/Flash.
Works swell.
-Ben
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Dazed and confused? I don't think so. Just "plain lost" will do. :D |
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Ttelmah
Joined: 11 Mar 2010
Posts: 19535
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| Posted: Thu Apr 09, 2015 1:14 am |
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The EEPROM functions on the 30F chips read and write 16bit words, not bytes.
If you look at the example. ex_intee.c, you will see them simply test for the compiler version:
| Code: |
#if defined(__PCD__)
// dsPIC30F/dsPIC33F/PIC24 internal eeprom is 16bit wide
typedef int16 INTEE;
#else
typedef int8 INTEE;
#endif
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and they then declare the value they are reading and writing as "INTEE value".
The manual is wrong, in that while it says that 'read_eeprom' returns either 8 or 16bit, on the write_eeprom function, it says that the value is 8bit. However it isn't. The function writes 16bit lumps on these larger PIC's.
So:
| Code: |
void weeprom(unsigned int16 addr, unsigned int16 val)
{
write_eeprom(addr,val);
}
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Writes a 16bit value to the EEPROM. |
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