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Hi I want to store a floating point number to a location in eeprom. This is my code float resulta; unsigned char *introm_var0 = (unsigned char *) 0xD40; resulta = 0.56; *introm_var0 = resulta; The problem is that it stores 00 in that location. Do i have to use some logic to convert my floating point number to hex and then store it. or is there any other method to do it. Anish |
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floating point no in eeprom
Started by ●May 29, 2003
Reply by ●May 29, 20032003-05-29
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Anish, You are an area where the names somewhat misleading due to accidents of computer history. You need to erase the EEPROM sector and re-program it. It is not nearly as simple as doing a store into RAM. If you are lucky there is a C library function to do this, but you will need to tell the C library function the clock speed you are using. Many compilers do not have this function. In this case you must write on yourself or modify some example code. The section of your processor's documentation on EEPROM will likely give a flow chart for programming EEPROM. If you look at the Motorola Semiconductor web site, you can find the documentation and probably an "Application Note" with some sample code. You must be careful to match the EEPROM programming algorithm to the processor. Motorola so far has had 3 different designs of EEPROM control in HC(S)-12 processors. Hope this helps. If you find it unclear, please ask some more questions. Further Notes below. Steve At 04:08 PM 5/29/2003, you wrote: >Hi >I want to store a floating point number to a location in eeprom. >This is my code > >float resulta; >unsigned char *introm_var0 = (unsigned char *) 0xD40; >resulta = 0.56; >*introm_var0 = resulta; > >The problem is that it stores 00 in that location. The full name of EEPROM is "Electrically Erasable Programmable Read Only Memory". The effect you are seeing is the "Read Only" feature. A better name is "Non Volatile Memory" and some of the Motorola documentation is using that term. Historically ROM (true "Read Only Memory") was soon replaced with various kinds of "ROM" that could be written. These were called "Programmable". The word "Programmable" suggests the truth that changing the contents requires a multi-step program of some kind, not a just a simple write. >Do i have to use some logic to convert my floating point number to >hex and then store it. or is there any other method to do it. The hex conversion is only required by the EEPROM programmers that work from an external input, such as a file in your PC or a file sent to the HC-12 through the SCI. These files are eventually read by a program in the HC-12 which converts the hex into binary before programming the data into flash or EEPROM. The data stored in HC-12 memory is all binary. Floating point numbers stored in RAM, EEPROM and flash all have the same binary values. >Anish > ><http://ashnin.com/clk/muryutaitakenattogyo?YH313099&yhad95056>1fdd15f.jpg" target="_blank" rel="nofollow">http://rd.yahoo.com/M$4522.3313099.4604523.1512248/D=egroupweb/S06554205:HM/A95056/R=0/*http://ashnin.com/clk/muryutaitakenattogyo?YH313099&yhad95056>1fdd15f.jpg >1fdd1cd.jpg > >-------------------- >>http://www.motorola.com/mcu >">http://docs.yahoo.com/info/terms/>Yahoo! Terms of Service. ************************************************************************* Steve Russell mailto: Senior Software Design Engineer http://www.nohau.com Nohau Corporation phone: (408)866-1820 51 East Campbell Avenue fax: (408)378-7869 Campbell, CA 95008 ************************************************************************* |
Reply by ●May 30, 20032003-05-30
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You need to treat the float as a sequence of characters and write them sequentially For example: *src = (unsigned char *) &resulta; for (i = 0; i < sizeof(float); i++) { *(introm_var0++) = *(src++); } this all assumes you're using a compiler that provides proper timing to write to EEPROM locations. At 11:08 PM 5/29/2003 +0000, you wrote: >Hi >I want to store a floating point number to a location in eeprom. >This is my code > > float resulta; > unsigned char *introm_var0 = (unsigned char *) 0xD40; > resulta = 0.56; > *introm_var0 = resulta; > >The problem is that it stores 00 in that location. > >Do i have to use some logic to convert my floating point number to >hex and then store it. or is there any other method to do it. > >Anish > >-------------------- > >">http://docs.yahoo.com/info/terms/ -------------------- Jim Bacon Software Engineer Melles Griot Electro-Optics -- Longmont, Colorado 720-494-4938 x329 |
