On 2012-09-21, at 5:30 AM, Sean Breheny wrote: > I think Veronica is trying to do this with FLASH, though, not EEPROM, Correct, using the on board flash. On 2012-09-21, at 6:00 AM, Isaac Marino Bavaresco wrote: > It may work, but first check what the datasheet of the PIC24FJ64GA004 > family (39881D) says: I'm using a PIC24FG256GB110 > "With RTSP, the user may write program memory data in blocks of 64 > instructions (192 bytes) at a time, and erase program memory in blocks > of 512 instructions (1536 bytes) at a time." 39697B Section 4.2 "The PIC24F Flash program memory array is organized into rows of 64 instructions or 192 bytes. RTSP allows the user to erase blocks of eight rows (512 instructions) at a time and to program one row at a time. It is also possible to program single words."=20 There is a programming example in section 4.6.2 for a single word. However, there is a note "Writing to a location multiple times without erasing is not recommended." In practise I would probably have a 4 byte 'tally' counter with a bit chang= e per 2 minutes giving me an hour although I could use more bytes for a lon= g time between erases. I have submitted a ticket to MC to ask them and ask about the basis of the = note. We'll see what they say. As ever, thanks everyone Veronica --=20 http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .