QSPI sample pgm

lel_chen — Thu, 06 Aug 2009 18:47:04 GMT

Hi,
     I need to read/write data to external flash using SPI.
For this, I was referring to the sample program given in "\Freescale MQX 3.2\mqx\examples\qspi".
I find the following definitions there:
-----------------------------------------------
/* The 25LC640 QSPI Serial EEPROM instructions */
#define TEST_ROM_WRITE_STATUS             0x01
#define TEST_ROM_WRITE_DATA               0x02
#define TEST_ROM_READ_DATA                0x03
#define TEST_ROM_RESET_WRITE_ENABLE_LATCH 0x04
#define TEST_ROM_READ_STATUS              0x05
#define TEST_ROM_SET_WRITE_ENABLE_LATCH   0x06
-----------------------------------------------

- Where are these definitions derived from?
- Will these definitions remain the same if I connect a SDRAM card instead of EEPROM?

The ctl in use is M52259.

Thanks,
Chen

Re: QSPI sample pgm

JuroV — Thu, 06 Aug 2009 20:49:43 GMT

Hello.

these definitions come from Microchip 25AA640A/25LC640A datasheet (http://ww1.microchip.com/downloads/en/DeviceDoc/21830C.pdf), page #7.

SDRAM is really uncompatible with such EEPROMs, primarily due to the fact that SDRAM is accessed with parallel bus instead of serial data access

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Re: QSPI sample pgm