I am trying to program the 25C320 EEPROM from my PIC16F628 microcontroller. I even have a sample Microchip pgm that does examples of the fundamental operatiuons
Trouble is, my version of this pgm originally worked and now doesn't and I am getting sporatic results
I have great plans for using this EEPROM and would like to know if there are common problems with these devices
Larryk
schreef in bericht news: snipped-for-privacy@i40g2000cwc.googlegroups.com...
Perhaps you zapped the outputs of your PIC16F628. Or zapped them half. Check the signals with an oscilloscope.
I assume you didn't go beyond the 1 million erase/write cycles.
-- Thanks, Frank. (remove \'q\' and \'.invalid\' when replying by email)
What did you do between the time when it worked and the time when it didn't?
Thanks, Rich
the program gives a sample of each command. write enable, write a byte, read a byte, read status register
I tried to expand these samples into practical loops of of writes and reads. At one point I apparently wrote 3 bytes and could read back the 2nd & 3rd but the 1st byte was all 1's.
But even this pgm failed to work subsequently. I will probably still go back to the sample pgm, but I have been trying different things with the clock and throwing in write enables, etc.
I know I will debug this, but just looking for ideas. Larryk
Ok, here is your problem.
Now you did backup the version that worked to compare against, didn't you.
Are you remembering to check the write-in-progress bit in the status register?
Luhan
thanks for all the help
there are 2 things I am working on
one thing the app notes specified was a 10k pullup resistor for cs (chip select) which is active low - I am wiring this in right now
the other thing stressed was setting and reading the status register on the EEPROM. I will put in code to set this properly. My understanding was that wiring /WP and /hold high I could override any settings of the status register.
there is a WIP check in my code already and it may be working OK.
no problem with 1 million writes and I do go from one PIC unit to another my programmer I developed myself I go from assembly lang code to burnt chip in 25 seconds the PIC16F628 has been very dependable but it originally took me over a year to get any signs of life out of it as I studied the 160 pages of specs and 30 pages of specs for programming the PIC !
Once I get to pgm this EEPROM, I have plans for labeling files, searching for files, etc.
The cs pullup is not manitory since it is driven by an output-only pin on the PIC. The same goes for Clock line. You *need* about a 2k pullup on the Data line which is bi-directional.
Luhan Monat (luhanxmonat-at-yahoo^dot^com)
signals off! even tho I haven't had chance to run all my programs, I think I've found the problem a loose connection on the SCK (clock) line from PIC to EEPROM don't know whether to rejoice or cry ! I've learned a few pointers from the discussions - thanks Larryk
last word -- the bad solder connection was not the only problem. I had to tweek software routines BYTIN and BITIN before things worked.
Interesting note: the tradeoff in using serially interfacing memory units: simpler hardware, more complex software. Conventional mem units need maybe 12 pins for address, and 8 pins for data. But only signal you need to send is a WRITE or a READ!
But I feel happier with minimal hardware and extensive software ! Larryk
ElectronDepot website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.