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LPC3250 EMC interfacing with SRAM

sumit negi

hi,
We are trying to use LPC3250 EMC for interfacing SRAM ,when we are writing a single value we are seeing2 chip select, 2 write pulses.

what can be the problem

Regards and Thanks
Sumit

Parents
  • 0 in reply to sumit negi

    First - is there a reason why you avoid formatting your code as code? Do you feel that it gets too easy to read with proper formatting?

    Secondly:

    #define CS0_read_16 (*(volatile unsigned short *)(0xE0000000))

void main () {
    emc_init();
    emc0_init();
    while (1) {
        CS0_read_16=0x5555;
    }
}


    will expand into:

    void main () {
    emc_init();
    emc0_init();
    while (1) {
        (*(volatile unsigned short*)(0xE0000000)) = 0x5555;
    }
}


    Exactly how much do you think that looks like a read? Doesn't it look like a write of the value 0x5555 to you?

    The following have a slightly larger chance of actually performing a memory read:

    my_var = CS0_read_16;

    By the way - what is the meaning of the "read" part of the name of your #define? Is it to inform that you may only read - not write - using the pointer? Sometimes "const" can be a nice keyword to have the compiler verify that attemts are not made to write to read-only variables.

Reply
  • 0 in reply to sumit negi

    First - is there a reason why you avoid formatting your code as code? Do you feel that it gets too easy to read with proper formatting?

    Secondly:

    #define CS0_read_16 (*(volatile unsigned short *)(0xE0000000))

void main () {
    emc_init();
    emc0_init();
    while (1) {
        CS0_read_16=0x5555;
    }
}


    will expand into:

    void main () {
    emc_init();
    emc0_init();
    while (1) {
        (*(volatile unsigned short*)(0xE0000000)) = 0x5555;
    }
}


    Exactly how much do you think that looks like a read? Doesn't it look like a write of the value 0x5555 to you?

    The following have a slightly larger chance of actually performing a memory read:

    my_var = CS0_read_16;

    By the way - what is the meaning of the "read" part of the name of your #define? Is it to inform that you may only read - not write - using the pointer? Sometimes "const" can be a nice keyword to have the compiler verify that attemts are not made to write to read-only variables.

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