How to connect 8bit SRAM with AM3357 GPMC bus?mux mode

vc ip

Other Parts Discussed in Thread: AM3357

I will extend 8bit SRAM with AM3357 GPMC bus, used mux mode,
AM335X GPMC_AD0-AD7 connect SRAM D0-D7, but how to connect Address line of SRAM?

A:
AM335X GPMC_AD0 --> SRAM A0 (through latch)
AM335X GPMC_AD1 --> SRAM A1 (through latch)
......
AM335X GPMC_AD14--> SRAM A14 (through latch)

B:
AM335X GPMC_AD1 --> SRAM A0 (through latch)
AM335X GPMC_AD2 --> SRAM A1 (through latch)
......
AM335X GPMC_AD15--> SRAM A14 (through latch)

which connect is right?
Thanks

over 11 years ago

0 Biser Gatchev-XID over 11 years ago

TI__Guru**** 393215 points

Your connection A is the correct one. Please check Table 7-5 in the AM335X TRM Rev. I.

0 vc ip over 11 years ago in reply to Biser Gatchev-XID

Intellectual 290 points

Thanks biser.

Does mux mode support 8-bit?

I remember you said AD and AAD-mux modes work only on 16-bit bus. on 8-bit bus how to read/write?

I read/write uesd 16-bit mode, lose hight byte?

devicesize set 16-bit?

Thanks

0 Biser Gatchev-XID over 11 years ago in reply to vc ip

TI__Guru**** 393215 points

No, AD-mux mode supports 8-bit devices. However I misled you about addressing: Address bits A[16:1] are output on pins AD[15:0].

0 vc ip over 11 years ago in reply to Biser Gatchev-XID

Intellectual 290 points

if that, I must set devicesize to 8-bit?

because

A1(process) - A0(SRAM)

A2(process) - A1(SRAM)

so I must

read.w / write.w use 16-bit r/w, lose hight byte?

or B:

read.b/write.b, addr is 0,2,4,...?

Thanks!

0 Biser Gatchev-XID over 11 years ago in reply to vc ip

TI__Guru**** 393215 points

I believe it will be the second case.

0 vc ip over 11 years ago in reply to Biser Gatchev-XID

Intellectual 290 points

Thanks Biser.

That is to say, because AD0->A1, so Table7-5 of TRM list Multiplexed Address Data 16-Bit Device only, if you want to 8-Bit device, r/w address must is 0,2,4...

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How to connect 8bit SRAM with AM3357 GPMC bus?mux mode