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TMS320F28377D: EMIF interface 1 address line 20 AND 21 is missing from the manual.

Peter Adamcik
Expert 1425 points
Part Number: TMS320F28377D


Hi Guys again LOL. SERIOUS PROBLEM.

I'm connecting a 4MB (Megabyte) SRAM on the EMIF F28377D and while assigning the address lines I find that address lines 20 and 21 are missing from the manual.

The manual says that there are 22 address lines which means to me EM1A0 to EM1A21 which equals 22 address lines equal to 4MB's of address space but the manual only lists EM1A0 to EM1A19 address lines. I even did a search in the PDF for EM1A20 and EM1A21 and search said NOT FOUND. Where is EM1A20 AND EM1A21?

Please let me know. This will be a project breaker if I can't get 22 address pins like the manual says. Well I guess I can get away with 2 meg which is 21 address lines but 20 address lines is only 1MB, not enough.

I know I can use PORTA as the address lines and PORTB as the data lines but the IO PORTS top speed is only 25Mhz, the EMIF is 100Mhz. 

Pete :)

  • 0
    TI__Expert 4610 points

    Hi Pete,

    You can access 4MB of data in 32bit mode with just 20 address pins(EM1A[19:0]).  1M locations x 32bit => 4MB. If you are using 16 or 8 bit memory, then you would need additional address pins (1 more for 16bit and 2 more for 8bit)  to access 4MB of memory. This can be achieved using the EM1BA[1:0] pins. This is captured under the "Interfacing to Asynchronous Memory" section of EMIF chapter in the Technical Reference manual. However there are few restrictions with respect to pinmux options. I suggest you to refer the pin mapping section in the below application note

    https://www.ti.com/lit/an/sprac96a/sprac96a.pdf

    Regards,
    Praveen

    Note: If my post answers your query, please click "This resolved my issue" button.

  • 0 in reply to Praveen Kumar Ravichandran
    TI__Guru** 115431 points

    Peter,

    As Praveen mentioned, 22 address lines comes from the fact that there are 20 dedicated address lines + 2 address lines for 16bit and 8bit. Hope that is clear. If you are using 16bit memory then you need to use another GPIO pin as MSB address lines to access 4MB space.

    Regards,

    Vivek Singh