EMC Bank Select Connection for 2-Bank SDRAM on LPC4078FET180

betachen — Mon, 03 Oct 2016 02:43:32 GMT

Hi, team,

According to the user manual, the bank select signals are from A14 and A13 pins. I need your confirmation that

when the chosen SDRAM only has 2 banks, should we start the connection from BA0 or BA1? (which one should be used for only 2-bank SDRAM?)

Thank you very much.

Best regards,

beta

Re: EMC Bank Select Connection for 2-Bank SDRAM on LPC4078FET180

ursaminor — Mon, 03 Oct 2016 09:26:02 GMT

Depending on configuration, the bank select signal may appear on EMC_A13 or on EMC_A14. The good news is that for the two-bank parts supported by this EMC it is possible to select the address line at run-time: Either RBC or BRC addressing scheme will always work on a given board, no matter which of EMC_A13 or EMC_A14 is connected to the SDRAM BA line. The bad news is that only one of RBC and BRC modes works, so if you target a specific mode, you must know the address line beforehand.

If the bank select address bit in the logical address used by the CPU is on an odd position, the EMC will use EMC_A14. If the bank select address bit is on an even position, the EMC will use EMC_A13.

Example:

32-bit bus, two 16-bit 16 MBit devices (1Mx16) with 11 row bits and 8 column bits.

a) RBC mode:

A[1:0] of the logical address select a byte in the 32-bit data word from SDRAM.

A[9:2] form the 8-bit column address

A[10] is the bank select bit

A[21:11] form the 11-bit row address

--> EMC_A13 is used for bank select because 10 is an even number

b) BRC mode:

A[1:0] of the logical address select a byte in the 32-bit data word from SDRAM.

A[9:2] form the 8-bit column address

A[20:10] form the 11-bit row address

A[21] is the bank select bit

--> EMC_A14 is used for bank select because 21 is an odd number

Summary:

16-bit bus, one 16M device with R=11, C=8, RBC mode --> A14

16-bit bus, one 16M device with R=11, C=8, BRC mode --> A13

16-bit bus, two 16M devices with R=11, C=9, RBC mode --> A13

16-bit bus, two 16M devices with R=11, C=9, BRC mode --> A14

32-bit bus, two 16M device with R=11, C=8, RBC mode --> A13

32-bit bus, two 16M device with R=11, C=8, BRC mode --> A14

32-bit bus, four 16M devices with R=11, C=9, RBC mode --> A14

32-bit bus, four 16M devices with R=11, C=9, BRC mode --> A13

Re: EMC Bank Select Connection for 2-Bank SDRAM on LPC4078FET180

betachen — Tue, 04 Oct 2016 06:38:31 GMT

Thank you very much for the clear explanation!

topic Re: EMC Bank Select Connection for 2-Bank SDRAM on LPC4078FET180 in LPC Microcontrollers

EMC Bank Select Connection for 2-Bank SDRAM on LPC4078FET180

Re: EMC Bank Select Connection for 2-Bank SDRAM on LPC4078FET180

Re: EMC Bank Select Connection for 2-Bank SDRAM on LPC4078FET180