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SDcard Read/Write missing/wrong data

Wouter Schol

Hi there,

I am using an own PCB with Luminary lm3s8962 (based on the evaluation board) with LabVIEW for ARM and KEIL uVision V3.85

In the past I've been developing code to, Log some data to/Read logfiles from, a microSD card without problems.

The data that is being logged is become a little bit more and at this moment I get corrupted data on/from the microSD card. I am using SanDisk 2 GB microSD's.

problem one: When I write enough data for a longer time I see that sometimes the data is wrong. I tested this behavior and I can reproduce it. The data size is OK but where I expect data like:
112;112;112;112;112;112 I see:
112;112;11;111;1112;112

sometimes the SDcard copies old or wrong data to that position that is wrong.

I've made a change which decrease the buffer per write. Now I don't see this problem anymore.
Is this an known issue?

problem two: When I read files from the microSD card on my embedded ARM and read the data via USB, I get wrong data (the first bytes are looking like a directory table of FAT)
I didn't made any change to the USB Read protocol and I wipe the microSD before every test.

When I read the microSD card in Windows, there are no problems.
Is there someone that is also getting strange behavior like this?

Parents
  • 0 in reply to ImPer Westermark

    The cards are exactly the same formatted, 512 bytes sectors, 32k clusters.
    under linux (fedora) with: dd if=/dev/zero of=/dev/sdc bs=2M <-- to wipe the cards
    mkdosfs -F 16 /dev/sdc -I <-- -F 16 for FAT16 -I to force it (no partition/MBR)

    I Made dd copies of the unbranded and SanDisk, and those are the same written. (before and after the embedded write actions)
    but when I read on the ARM: unbranded = OK, SanDisk = strange data and sometimes faults in the data.

Reply
  • 0 in reply to ImPer Westermark

    The cards are exactly the same formatted, 512 bytes sectors, 32k clusters.
    under linux (fedora) with: dd if=/dev/zero of=/dev/sdc bs=2M <-- to wipe the cards
    mkdosfs -F 16 /dev/sdc -I <-- -F 16 for FAT16 -I to force it (no partition/MBR)

    I Made dd copies of the unbranded and SanDisk, and those are the same written. (before and after the embedded write actions)
    but when I read on the ARM: unbranded = OK, SanDisk = strange data and sometimes faults in the data.

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