Post by thread:Read/Write to Data EEEPROM

At 15:34 16/05/97 -0400, Francesco Cembrola wrote: >I am a little confused on the purpuse of having the Data EEPROM. >Can someone explain the use of it? let's say you have some data that you still want to have when the pic is powered up the next time: how'd you do that? since it's some kind of "online" data, you can't put it in the code prom (you don't know it when programming it), and if you put it into ram, it's gone after power down. so you put it into eeprom, and bingo -- you have a non volatile read- and writeable memory. >Also can I have an exsample of how to write a value to the first location in >the above memory and then read it back again? Page 11-31 ff. of the 96/97 data book shows how to do it, they even have a code example there. (All theory, I'll have to check it by myself since I'm going to use it, but only in a couple of days.) I thought of writing some sample code here, but it's really all there -- provided it works as written. For the first location you put 0 in EEADR and your data in EEDATA, and then do as they say.

>At 15:34 16/05/97 -0400, Francesco Cembrola wrote: >>I am a little confused on the purpuse of having the Data EEPROM. >>Can someone explain the use of it? > >let's say you have some data that you still want to have when the pic is >powered up the next time: how'd you do that? since it's some kind of >"online" data, you can't put it in the code prom (you don't know it when >programming it), and if you put it into ram, it's gone after power down. so >you put it into eeprom, and bingo -- you have a non volatile read- and >writeable memory. > >>Also can I have an exsample of how to write a value to the first location in >>the above memory and then read it back again? Which 'book' are you refering to below? And where might I find a copy of this book? > http://ic.mankato.mn.us/~douglas >Page 11-31 ff. of the 96/97 data book shows how to do it, they even have a >code example there. (All theory, I'll have to check it by myself since I'm >going to use it, but only in a couple of days.) > >I thought of writing some sample code here, but it's really all there -- >provided it works as written. For the first location you put 0 in EEADR and >your data in EEDATA, and then do as they say. > >

At 19:38 16/05/97 -0500, . wrote: >Which 'book' are you refering to below? And where might I find a copy of >this book? > >>Page 11-31 ff. of the 96/97 data book shows how to do it, they even have a >>code example there. (All theory, I'll have to check it by myself since I'm >>going to use it, but only in a couple of days.) I was refering to the PIC16/17 Microcontroller Data Book, edition 1996/1997 -- which I think is _THE_BOOK_ to get when you try to make something other than necklaces with PICs. I think Microchip sends it to everybody who requests it (either in paper form or with some other info as a CD-ROM). They are even here in Brazil readily available, where you don't see a trace of data books from other manufacturers.

. wrote: {Quote hidden}> > >At 15:34 16/05/97 -0400, Francesco Cembrola wrote: > >>I am a little confused on the purpuse of having the Data EEPROM. > >>Can someone explain the use of it? > > > >let's say you have some data that you still want to have when the pic is > >powered up the next time: how'd you do that? since it's some kind of > >"online" data, you can't put it in the code prom (you don't know it when > >programming it), and if you put it into ram, it's gone after power down. so > >you put it into eeprom, and bingo -- you have a non volatile read- and > >writeable memory. > > > >>Also can I have an exsample of how to write a value to the first location in > >>the above memory and then read it back again? > > Which 'book' are you refering to below? And where might I find a copy of > this book? > > > > > http://ic.mankato.mn.us/~douglas > > >Page 11-31 ff. of the 96/97 data book shows how to do it, they even have a > >code example there. (All theory, I'll have to check it by myself since I'm > >going to use it, but only in a couple of days.) > > > >I thought of writing some sample code here, but it's really all there -- > >provided it works as written. For the first location you put 0 in EEADR and > >your data in EEDATA, and then do as they say. > > > > one of the gotcha's that I see on the list often is trying to write consecutive bytes to eeprom without allowing for the required delay between writes. Tony M.

At 07:38 19/05/97 -0400, Tony Matthews wrote: > >I thought of writing some sample code here, but it's really all there -- > >provided it works as written. For the first location you put 0 in EEADR and > >your data in EEDATA, and then do as they say. > > >one of the gotcha's that I see on the list often is trying to write >consecutive bytes to eeprom without allowing for the required delay >between writes. Tony M. Which (the required delay) is given by either the WR bit being cleared or the EEIF bit being set (with possibly an interrupt associated). Is there any difference between the two when polling for the end of the write cycle?

Gerhard Fiedler wrote: > > At 07:38 19/05/97 -0400, Tony Matthews wrote: > > >I thought of writing some sample code here, but it's really all there -- > > >provided it works as written. For the first location you put 0 in EEADR and > > >your data in EEDATA, and then do as they say. > > > > >one of the gotcha's that I see on the list often is trying to write > >consecutive bytes to eeprom without allowing for the required delay > >between writes. Tony M. > > Which (the required delay) is given by either the WR bit being cleared or > the EEIF bit being set (with possibly an interrupt associated). Is there > any difference between the two when polling for the end of the write cycle? I generally have little or no programming words left over on a 16c84 so prefer to do other work during the 10 ms delay so I cannot advise you as to polling have'nt done it. luck Tony M.