Hi,

I am doing some work with images and have found that when the arrays >22kb then the system hangs. So I have decided that I need a way of storing large chunks of data that I can read and write to quickly (19200 bytes in <100ms).

I tried the local file system on the mbed but this took around 0.9 seconds to write a 19200 byte file to. Would an SD card be quicker? or are then any other toys out there that would work better?

Does anyone have any experience with this and have any timing data they would share?

Thanks Martin

You could try a memory chip, SPI, can be quite quick, Especially if you get one that has 16, or possibly 32 bit data size, And optomise your data size, to match storage size (width)

If this is not fast enough, then parallel memory can be used. But be careful, if you pick a bad mix of MBED pins, with bus out, It might be slower than SPI!

There is also I2S, as used in a VGA example. But I have not got I2S to work myself.

BTW, all of the files systems, have padding of some type, So a dedicated chip might have enough of a speed advantage. Have a look on WWW.microchip.com for memory devices.

Enjoy Ceri

Hi Martin,

Yes, any proper storage will be much quicker than the semi hosted file system; I'd start by trying an sd card or USB stick if you want a file system, or a spi flash chip if you just want some raw storage (of course, you can use USB or sd card as block device too)

Simon

i want to read images from pc through mbed ? how to do it?