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I'd like to have my Arduino write some files and store them somewhere. They won't be big files, but the 1Mb available on the device won't be enough. I know an SD card is the popular solution, but the smallest SD card here is a little expensive, and more than enough, I mean, I could get by with around 10mb (or even less than that), so it would be wasteful to add a 1gb SD card (or a 512mb, 256 or 128), and it would be expensive too. Is there an intermediate solution? Some way cheap of adding just a bit more?

Thanks

closed as primarily opinion-based by Juraj, sempaiscuba, VE7JRO, gre_gor, Greenonline Nov 21 '18 at 23:37

Many good questions generate some degree of opinion based on expert experience, but answers to this question will tend to be almost entirely based on opinions, rather than facts, references, or specific expertise. If this question can be reworded to fit the rules in the help center, please edit the question.

  • 2
    SPI flash memory – Juraj Nov 15 '18 at 20:01
  • Or send them to the internet with a WiFi interface – Majenko Nov 15 '18 at 20:15
  • I like the SPI option, I'll have to research a bit more about it. – Pablo Grabarnik Nov 15 '18 at 20:15
  • I can't rely on the wifi option, there could be no signal where I want to use my project – Pablo Grabarnik Nov 15 '18 at 20:16
  • SD card is usually the cheapest option. – Majenko Nov 15 '18 at 20:31
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This may be relevant if you can get your hand on some old 30 Pin SIMM RAM.

Its a library some clever chap wrote to interface with 30-pin simm ram using an atmega328p on Arduino

https://github.com/zrafa/30pin-simm-ram-arduino

Also his video here: here https://youtu.be/Yah3ViEggxA

It is apparently quite wasteful though as you only get to use 256Kb of the RAM!

The author also states that "using this kind of RAM will put your Arduino CPU to refresh the SIMM RAM data part of the time. It means that your sketches (programs) could run a little slower than before. Also, we need to use most of the Arduino pins to be soldered with SIMM RAM pins so there will be just few available extra pins for your project."

  • Sorry I just noticed you want to add quite a bit of memory so this is probably not the answer you need. Still, I suppose it might be of use to someone who wants to work with recycled stuff. – John Nov 21 '18 at 14:05
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FRAM - nonvolatile like EEPROM, but fast read/write speeds like SRAM.

2 megabit (256 kilobyte) are pricey too, $6 at Digikey. But still less than the cost of two 1 megabit (128 kilobyte) at $4.70 each.

2 megabit (256 kilobyte) EEPROM are much less, ~$2.30, but way slower - after you transfer data in, there is a 5 or 10 millisecond write time to wait out.

1 megabit (128 kilobyte) SPI SRAMs are pricey too - $3.95 each.

I recently bought a quantity of SD cards, ~$5 for 32GB. Only needed 2, 4 would have been enough (storing up to 256 files totalling maybe 1 Mbyte) but can't find that small anymore.

SD card + socket is sounding more and more reasonable.

Sparkfun has a microSD with 5V/3.3V level converters (uses TXB0104) for under 5 dollars too (sale price for a week) as an example. https://www.sparkfun.com/products/13743

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