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Forum Index : Microcontroller and PC projects : FRAM chips...
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Grogster Admin Group  Joined: 31/12/2012 Location: New ZealandPosts: 9066 |
I read in another thread about FRAM chips now being used as replacements for EEPROM memory chips. These things look very interesting from a speed point of view, but also not having to poll the device or wait for page writes, as all data written to them in any amount is instant - very curious, and also allows for much easier coding, cos you don't have to watch that page boundry anymore. 
Does anyone here use any FRAM chips in their projects? The ones I found on element 14 are Ramtron 16Kbit ones(2KB), but there are other capacities. Prices seem quite cheap, with the 16Kb one being sold for $2 at element 14. Wikipedia mentions that FRAM has disadvantages such as higher cost, relatively low storage capacity etc. However, the writability of these chips is very impressive indeed - just the fact that you don't ever have to worry about page boundries again is enough to make me want to use them.  But lower power consumption, very fast operation up to 1MHz, read/write endurance of 100 trillion times, and data retention for up to 150 years is also extremely impressive.
I note that the Ramtrom parts don't allow you to set a slave address for I2C though - it is preset to 1010 + word-address for the command byte, meaning you can only ever have one FRAM of this type on the I2C bus, which is a little limiting, IMHO. Comments? Thoughts? Opinions? Smoke makes things work. When the smoke gets out, it stops! |
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| Grogster Admin Group Joined: 31/12/2012 Location: New ZealandPosts: 9066 |
Still reading my way through the datasheet. Wow..........  
EDIT: The 64Kb(8KB) and 256Kb(32KB) flavours of this chip do have the standard address pins A0,A1,A2 on pins 1, 2 and 3 of the chip. Must just be the wee fella that does not let you set a slave address for some reason.... Smoke makes things work. When the smoke gets out, it stops! |
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| WhiteWizzard Guru  Joined: 05/04/2013 Location: United KingdomPosts: 2794 |
For the 'eagle-eyed' out there, you will know I have mentioned FRAMs on several posts. I have used them in designs and they are BRILLIANT. Do a search on any major supplier (RS, Mouser, Farnel/Element14 etc) and you will see various parts/sizes. If using for a MicroMite then the only word of caution I have is make sure it is a 3V3 part (some are 5v only which is ok BUT not if you only use 3v3). Glad I'm sparking interest in these finally For everything Micromite visit micromite.org Direct Email: whitewizzard@micromite.o |
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| Grogster Admin Group Joined: 31/12/2012 Location: New ZealandPosts: 9066 |
Oh, WW - you have created a bonfire of interest for me.
My weapon of choice in this department so far is the FM24W256-G, which is a 256Kb(32KB) FRAM chip, for about $7 in our money. I can understand why they only offer these in non-DIL packages - they have such excellent specs, there should be no need to use DIL or socketed type memory. I guess if push came to shove, you can get that ChipQuik stuff to unsolder chips. SOIC 8-pin would be no problem at all, if proved to be the cause........ Smoke makes things work. When the smoke gets out, it stops! |
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| WhiteWizzard Guru Joined: 05/04/2013 Location: United KingdomPosts: 2794 |
@grogster Note that the FM24W256-G is a 5v part! Not tried a 5v FRAM on a 3v3 circuit but there is probably operational issues if trying to run it at 3v3 only. Go for a 3v3 part and you have a 100$ working solution 
WW For everything Micromite visit micromite.org Direct Email: whitewizzard@micromite.o |
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| WhiteWizzard Guru Joined: 05/04/2013 Location: United KingdomPosts: 2794 |
@Grogster: Check this one out:-FM31L278-G 32Kx8, I2C, 2v7-3v6. Works nicely with a MicroMite (if you need that much storage!) There is a massive 1Mbit FRAM (128Kx8): FM20L08-60-TG. It is a Parallel FRAM, 3.3V, in a 32-Pin TSOP-1 case. Costs a bit; but if you need the capacity . . . . WW For everything Micromite visit micromite.org Direct Email: whitewizzard@micromite.o |
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| Grogster Admin Group Joined: 31/12/2012 Location: New ZealandPosts: 9066 |
Datasheet for the device says on page 9, that voltage range is 2.7v through to 5.5v, with 3v3 being typical.... 
The device expects a two-byte word for the memory address. Assuming that you knew the decimal address, how would you break up that number into two variables representing the MSB and LSB? Lets say I wanted to write or read from address 25,000, and I have a variable A=25000 What would be the formula for taking a larger number like this, and splitting it into the two bytes I need to address the FRAM with? Smoke makes things work. When the smoke gets out, it stops! |
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TassyJim Guru Joined: 07/08/2011 Location: AustraliaPosts: 5913 |
provided that your starting number is small enough to fit in 16 bits; a= 25000
loByte= a MOD 256 hiByte = a\256 PRINT a, loByte, hiByte number = hiByte*256 + loByte PRINT number Jim VK7JH MMedit MMBasic Help |
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frackers Newbie  Joined: 06/11/2009 Location: New ZealandPosts: 23 |
I used an fm25640 some 12 years ago in a project - it worked really well. I was using it more as a RAM expander than for its non-volatile attributes but I still have all in the info here Great project if you understand AVR assembler
Robin down under - or are you up over |
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| Grogster Admin Group Joined: 31/12/2012 Location: New ZealandPosts: 9066 |
@ Jim - I end up with different numbers. Am I doing something wrong? 
@ frackers - thanks for the link - I will read it. Smoke makes things work. When the smoke gets out, it stops! |
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G8JCF Guru Joined: 15/05/2014 Location: United KingdomPosts: 676 |
@grog you have to use \ ie integer divide NOT / ie MSB = A \ 256 Peter The only Konstant is Change |
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| Grogster Admin Group Joined: 31/12/2012 Location: New ZealandPosts: 9066 |
Ahhhhhhhhhhhhh - Thank you very much!
That works fine - my mistake!  Smoke makes things work. When the smoke gets out, it stops! |
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vasi Guru Joined: 23/03/2007 Location: RomaniaPosts: 1697 |
Now I'm thinking at Gill's anemometer logger... Hobbit name: Togo Toadfoot of Frogmorton Elvish name: Mablung Miriel Beyound Arduino Lang |
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centrex Guru Joined: 13/11/2011 Location: AustraliaPosts: 320 |
Hi Grogster, WhiteWizard, others The Fram chips interest me to use with TassyJims BMP085 software which works very well on BigMicks MuP board. I would like to be able to record the information for later retrieval, but and it is a BIG but I have no idea how to use the chip for this purpose other than it is I2C. Writing the code to save the data and then being able to access at some future date is beyond me. The 3.3 volt FRAM that WhiteWizard mentiond is about $17 here in Aus. Making a pcb to hold the chip and connecting to the MuP is not a problem. It is the code that is my problem any help would be appreciated. It would probably help the rocket poster also. Regards Cliff Cliff |
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| WhiteWizzard Guru Joined: 05/04/2013 Location: United KingdomPosts: 2794 |
Hi Cliff, I would love to write some example code but I am out today and tomorrow. I will have a look at it at the start of next week BUT Grogster maybe able to come up with something for you. I have several FRAMs next to me (still in anti-static packaging) so it will take a couple of days to fire up a PCB and some code. What timescales do you have? If not too urgent then should have something for you next week. Out of interest - how much storage capacity do you think you require? WW For everything Micromite visit micromite.org Direct Email: whitewizzard@micromite.o |
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| centrex Guru Joined: 13/11/2011 Location: AustraliaPosts: 320 |
Hi WhiteWizard Terrific, no real time scale, I have to get one of the chips which could take a week or more and build a pcb. Am I right in that the FRAM you suggested FM31L278G also has a real time clock imbedded. I just think this device with the MuP would make a great data logger and if it has the RTC all the better for time stamping. As far as capacity that is something that I would have to be guided by you, for instance say I was using TassyJims software to give sea level barometric pressure and a date stamp. Many thanks Cliff Cliff |
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| WhiteWizzard Guru Joined: 05/04/2013 Location: United KingdomPosts: 2794 |
Hi Cliff, Yes, the FM31L278G does have an RTC included but that isn't why I recommended it (mentioned purely for the 1Mbit capacity). However, that said, it may be possible to utilise it for Time/Date stamping BUT it probably won't work with MMBasic's inbuilt RTC SETTIME/GETTIME commands. It should be easy enough though to write your own functions to perform the same functionality (essentially set/get the Time$ & Date$ values). I haven't studied Jim's barometric code to see what it is outputting in terms of data volume, but if you say what information you require (i.e barometric pressure + Time & Date); convert this into a number of bytes per record; and then most importantly say how often you want to sample along with the length of time between 'downloads'. This will dictate a capacity which I then recommend doubling to allow for 'expansion'. Let us know the frequency of samples you think you require (i.e. once every 10 seconds, etc) and also the duration between downloads (i.e time between each 'extraction' of data; i.e. once a week). Finally, give us your best 'guesstimate' as to how many bytes each pressure reading takes (like I say, I haven't looked at Jim's code - sorry if the answer is in there!). Will be happy to make you a FRAM module if you so wish - I'm sure others could use this too.
(I was designing one about three months ago but other priorities took over) WW For everything Micromite visit micromite.org Direct Email: whitewizzard@micromite.o |
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bigmik Guru Joined: 20/06/2011 Location: AustraliaPosts: 2870 |
Hi Cliff, All, If you can use the fm32l278 instead RS Components list these as $9.05 ea Plus GST but they offer free next day delivery for ONLINE orders. I had a quick look at the data and they seem to be the same but have no XTAL facility.. I dont know off hand if that is good or bad. RS Components Link Regards, Mick Mick's uMite Stuff can be found >>> HERE (Kindly hosted by Dontronics) <<< |
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| WhiteWizzard Guru Joined: 05/04/2013 Location: United KingdomPosts: 2794 |
Hi Mick, Do you fancy spinning up a MuP-FRAM. I reckon it would have a lot of interest as a logger board for the MuP. Include a DS18B20 option (with resistor) for use as temp logger too.
Just an idea . . . . . WW For everything Micromite visit micromite.org Direct Email: whitewizzard@micromite.o |
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| bigmik Guru Joined: 20/06/2011 Location: AustraliaPosts: 2870 |
Hi Phil, The thought for a `sensor' board has been in the back of my mind but at the moment there are two things in the way. The first is time as this is now the busiest time for my working year with Melbourne's Spring Racing Carnival getting in the way of just about everything.. In just 1 week we will be fully into it with 90+ hour weeks this wont let up till mid November where it dies away pretty rapidly (for a few weeks) till the SUMMER season starts.. The other is funds.. At this stage I have to keep new boards down a bit as apart from MuP, which has been an overwhelming success, none of my other boards are doing much and are running at a loss.. Not that this is a big deal as we dont talk huge amounts here but each board costs $60 - $100 plus or minus to get a run of 50 done and I am really doing it for the fun and to get some stock for myself so I am not complaining. As you can see even that little 15mm square jobbie I was playing with would cost 50c each buying 150 of them which I doubt I would ever move.. I have been looking at other options and most of the cheap FAB houses have restrictions on panelising the boards.. You can get 16 of these on a single 10cm square board.. Most either wont allow panelising or limit to about 5 per panel. I am always interested in doing a board for someone if they wish.. HallDave was instrumental in getting 2 of my boards going and we struck a deal we were both happy with. Anyway I will be interested but I cannot promise anything at this very moment. Ideas are always welcome. Mick Mick's uMite Stuff can be found >>> HERE (Kindly hosted by Dontronics) <<< |
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