AM3517 WinCE6: SPI access to 128k nvram loses bytes

Timm F.

Hello,

trying to read a 128kb NVRAM (RAMTRON FM25V10) through the SPI2: driver, in a lot of cases, some bytes are missing.

Writing seems to be ok, as "writing one time and reading several times" sometimes produces a correct read result on all 128kbytes.

To give additional information, I provide the SPI parameters: f=24Mhz, Wordlength=8bit, tried with or without FIFO, DMA is disabled.

Also, I am using the SPI driver from the Technexion WinCE6 BSP.

What might be the reason for this behaviour?

Thanks in advance.

over 13 years ago

0 Awais Masood over 13 years ago

Intellectual 445 points

Hi,

Many SPI based memories require the chip select signal to be asserted during a complete operation that may span upon multiple data transfers. Its quite a chip specific thing and varies how a specific memory chip requires the chip select signal to behave. You may need to refer to the NVRAM documentation for that.

Regards,

Awais Masood

Mentor Embedded

Nucleus | Services | UI | Multi-OS

0 Timm F. over 13 years ago in reply to Awais Masood

Prodigy 100 points

Hello,

thanks for your reply.

I already took this into account, and made some DeviceIoControls to manually set / reset the chip select signal through the MCSPI_CHxCONF->Force flag.

The problem was another one: I forgot to use pullup resistors on the data lines

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AM3517 WinCE6: SPI access to 128k nvram loses bytes