SDRAM with 8-bit data bus connection

gtalocchino — Thu, 07 Apr 2022 16:02:51 GMT

We want to connect an RT1020 to an external SDRAM through SEMC. We are looking at ISSI IS42S81600F-7TLI. This memory has an 8-bit data bus. The RT1020 Reference Manual only has a table indicating the connection with a 16-bit SDRAM.

We assumed that the connection is as follows.

SEMC_DATA00 -> DQ0
SEMC_DATA01 -> DQ1
SEMC_DATA02 -> DQ2
SEMC_DATA03 -> DQ3
SEMC_DATA04 -> DQ4
SEMC_DATA05 -> DQ5
SEMC_DATA06 -> DQ6
SEMC_DATA07 -> DQ7
SEMC_ADDR00 -> A0
SEMC_ADDR01 -> A1
SEMC_ADDR02 -> A2
SEMC_ADDR03 -> A3
SEMC_ADDR04 -> A4
SEMC_ADDR05 -> A5
SEMC_ADDR06 -> A6
SEMC_ADDR07 - >A7
SEMC_ADDR08 -> A8
SEMC_ADDR09 -> A9
SEMC_ADDR10 -> A10
SEMC_ADDR11 -> A11
SEMC_BA0 -> BA0
SEMC_BA1 -> BA1
SEMC_WE -> WE
SEMC_CAS -> CAS
SEMC_RAS -> RAS
SEMC_CS0 -> CS
SEMC_DM0 -> DQM

Our main questions is about connection. The memory only has one "Data Input/Output Mask" (DQM). We have to connect it to DM0 or DM1 in SEMC?

There is one other thing to keep in mind using 8-bit data bus SDRAM memories?

Re: SDRAM with 8-bit data bus connection

jay_heng — Fri, 08 Apr 2022 07:32:22 GMT

SEMC supports 8/16 bit modes, so it is ok to connect 8bit SDRAM to SEMC

For 16bit SDRAM, SEMC_DM0 <-> SDRAM_DQML corresponds to DQ[7:0]; SEMC_DM1 <-> SDRAM_DQMH corresponds to DQ[15:8]

For 8bit SDRAM, SEMC_DM0 <-> SDRAM_DQM corresponds to DQ[7:0], Keep SEMC_DM1 NC

topic Re: SDRAM with 8-bit data bus connection in i.MX RT Crossover MCUs

SDRAM with 8-bit data bus connection

Re: SDRAM with 8-bit data bus connection