Stamp 2 architecture question
Tintin
Posts: 37
Maybe somebody can clearify a concern that's been bothering....
Here is a code snippet from a thermostat project I did a while ago:
(...)
TEMPERATURE VAR Byte
(...)
REQUEST_TEMP:
·HIGH ENABLE_TEMP····························································· ' enable temp chip
·SHIFTOUT DQ, CLK, LSBFIRST, [noparse][[/noparse]READ_TEMP]························· · ' ask to read temp
·SHIFTIN DQ, CLK, LSBPRE, [noparse][[/noparse]POINT\1, TEMPERATURE\7, SIGN\1]·· ' write as var TEMPERATURE
·LOW ENABLE_TEMP···························································· ·' disable temp chip
RETURN
(...)
Simply consider·the that·the·REQUEST_TEMP subroutine is looped·constantly·.· The·bs2 executes 4000 inst/sec and if we assume each line above is an instruction (incuding RETURN), and neglect all other·delay times, the·variable TEMPERATURE is written to once every 5 instructions.·
This means every 1.25 ms we write to TEMPERATURE.· Thus, after 3.5 hours we would have written to that variable 10 000 000 times.
My QUESTION:· Is the variable TEMPERATURE a eeprom memory location? If so, would·this program fail after 3.5 hours?· If not, where is the variable stored?
Thanks for the help,
Frank
Here is a code snippet from a thermostat project I did a while ago:
(...)
TEMPERATURE VAR Byte
(...)
REQUEST_TEMP:
·HIGH ENABLE_TEMP····························································· ' enable temp chip
·SHIFTOUT DQ, CLK, LSBFIRST, [noparse][[/noparse]READ_TEMP]························· · ' ask to read temp
·SHIFTIN DQ, CLK, LSBPRE, [noparse][[/noparse]POINT\1, TEMPERATURE\7, SIGN\1]·· ' write as var TEMPERATURE
·LOW ENABLE_TEMP···························································· ·' disable temp chip
RETURN
(...)
Simply consider·the that·the·REQUEST_TEMP subroutine is looped·constantly·.· The·bs2 executes 4000 inst/sec and if we assume each line above is an instruction (incuding RETURN), and neglect all other·delay times, the·variable TEMPERATURE is written to once every 5 instructions.·
This means every 1.25 ms we write to TEMPERATURE.· Thus, after 3.5 hours we would have written to that variable 10 000 000 times.
My QUESTION:· Is the variable TEMPERATURE a eeprom memory location? If so, would·this program fail after 3.5 hours?· If not, where is the variable stored?
Thanks for the help,
Frank
Comments
Every time the temperature device was queried, it reloaded the new temp into the TEMPERATURE variable.
No worries with wearing out the eeprom!
However, if you wanted to permanently store a particular value, use the WRITE command. See the help file on READ/WRITE.
Tom
Thanks again
·
RAM locations can not "wear out", On the PBASIC Stamp, only EEPROM can wear out.
Regards,
Bruce Bates
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