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TM4C1294NCPDT: EPI interface with CY62147 SRAM

cheng gu
Prodigy 90 points
Part Number: TM4C1294NCPDT

Tool/software:

Hi Team,

 we want to use the TMC129 EPI interface connect to external SRAM CY62147, the circuit is same as the circuit in the TI TM4C129 manual. below is the screenshot. my questions are

1. if my variable type are uint8_t, uint16_t or uint32_t, and I put the variable into the external SRAM chip CY62147, when I read/write the variable, can I just use simple C code like below, do I need add some delay or other operation? what is the speed of the read/write access?

 uint8_t variable=0x12;

uint16_t variable=0x1234;

uint32_t variable=0x12345678;

2. do I have to assign uint16_t and uint32_t variable at even start address?

3. if I am using RTOS, can I put RTOS heap memory into the external SRAM chip?

4. can I use the external SRAM same as micro's internal RAM? is there any consideration need to be note? thanks.

Best

Gu

  • 0
    TI__Guru**** 184346 points
    cheng gu said:

    1. if my variable type are uint8_t, uint16_t or uint32_t, and I put the variable into the external SRAM chip CY62147, when I read/write the variable, can I just use simple C code like below, do I need add some delay or other operation? what is the speed of the read/write access?

     uint8_t variable=0x12;

    uint16_t variable=0x1234;

    uint32_t variable=0x12345678;

    HI,

      I don't see a problem. There is a reference design with EPI used for SRAM at https://www.ti.com/tool/TIDM-TM4CFLASHSRAM. You can download the example code at /cfs-file/__key/communityserver-discussions-components-files/908/tidcaj1.zip

    cheng gu said:

    2. do I have to assign uint16_t and uint32_t variable at even start address?

    Normally, the compiler should take care of this.

    cheng gu said:

    3. if I am using RTOS, can I put RTOS heap memory into the external SRAM chip?

    I don't know how this works in TI-RTOS. Somehow you have to tell RTOS kernel which memory the heap should be allocated to. 

    cheng gu said:
    4. can I use the external SRAM same as micro's internal RAM? is there any consideration need to be note? thanks.

    You can use external RAM like internal RAM but of course the internal RAM is single cycle which is much faster than external SRAM. 

  • 0 in reply to Charles Tsai
    Prodigy 90 points

    Hi Charles,

     thank you for your quick response.

     in the TM4C129 manual, it has a sample EPI circuit with CY62147, but I can't find the exact read/write bandwidth speed of CY62147 with EPI interface, do you have such information? 

     below is the screenshot of CY62147 manual, does it mean the read/write speed of CY62147 with TM4C129 EPI interface is roughly 20MByte/second? thanks.

    Best

    Gu

  • +1 in reply to cheng gu
    TI__Guru**** 184346 points
    cheng gu said:

     in the TM4C129 manual, it has a sample EPI circuit with CY62147, but I can't find the exact read/write bandwidth speed of CY62147 with EPI interface, do you have such information? 

     below is the screenshot of CY62147 manual, does it mean the read/write speed of CY62147 with TM4C129 EPI interface is roughly 20MByte/second? thanks.

    The datasheet is just showing an example connections between the EPI and a 16-bit external SRAM. You will need to configure EPI module with proper wait states to accommodate the SRAM read/write speed per their specification.