I have a 2gb microSD card that I pulled from my Blackberry and I plugged it into my Netduino Plus, and I noticed that it is very slow to read files. It is even slow when using a USB-to-microSD card reader. I am comparing to the speed of a standard USB drive. Are USB read times normally faster than microSD, or am I doing something wrong? Is there a way to read USB drives with a Netduino, i.e. with a compatible USB shield or something? I need faster read times somehow. Even a 20kb file takes too long.
2gb microSD card read speed
Started by monewwq1, Jul 31 2011 11:37 PM
2 replies to this topic
#2
Chris Walker
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Posted 01 August 2011 - 12:28 AM
Hi Nick,
Different types of flash memory have different read/write speeds. What kind of speeds are you seeing?
A 20KB file should be read almost "instantly." If that's slow, it may be an issue with the card itself.
Also, please note that microcontrollers typically normally process small amounts of data...streaming many MBs of data per second requires fast flash media and can benefit from faster data buses.
Chris
#3
monewwq1
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Posted 01 August 2011 - 12:54 AM
Could be a problem with the SD card... I'm re-formatting it now. I don't have a second one around to try. Perhaps the issue is more related to my code and what I am doing. I am reading a file off of the SD card via a Filestream, and then I am sending the data out onto the Netduino's UART to another device. I am sending it at 1024 bytes at a time, but I wonder if I am running into speed issues because of the fact that I'm re-assembling it for transport onto the UART. The other device also then has to process it. I'm not sure where the bottleneck is. I'd like to think it isn't my code, but that's also possible.
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