GPMC with SRAM HY62256ALP non-mux mode

Hi,

Please describe your use case in more detail: GPMC connections to SRAM, software used, GPMC_CONFIG[7:1] register values.

Hi,

we are configured as non-multiplex mode.... and connection - "Figure 7-4. GPMC to 16-Bit Non-multiplexed Memory" which is mentioned in TI Technical reference manual and the configuration are mentioned below,

GPMC_CONFIG1 = 0x00000011

GPMC_CONFIG2 = 0x00080805

GPMC_CONFIG3 = 0x00000000

GPMC_CONFIG4 = 0x06030603

GPMC_CONFIG5 = 0x00060606

GPMC_CONFIG6 = 0x00000000

GPMC_CONFIG7 = 0x0000094F

HY62256ALP is a 32Kx8 SRAM. How can you connect it in 16-bit mode? Can you give me the exact part number? What is the access time of the device you use?

hi,

we are configured for 8-bit only... for connection reference only i mentioned that diagram "Figure 7-4. GPMC to 16-Bit Non-multiplexed Memory". is there any other connection diagram for 8-bit (except NAND) in TI reference manual...?

Exact part number is HY62256ALP-10............... at a speed of 70ns... and we don't know how to find out the access time...

Thank you,

We changed as per your suggestion... but now we are getting the same value in all the offset address places which we declared for last value...

example...

if we are setting value for two offset address,

  0x0F000001 = 0xA;

  0x0F000002 = 0x4;

while reading we are getting the same value in both address places as,

  0x0F000001 = 0x4;

  0x0F000002 = 0x4;

what is the reason for this...?

Thank you,

My guess is that you have connected the GPMC address lines wrongly. Check Table 7-5 "Non Multiplexed Address Data 8-Bit Device" column for the correct connections (AM335X TRM Rev. K).

But we have started with the address  GPMC_A[0] only....

Thank you,

Still i have confusion about access times of the device which i have connected... so i want to  use the gpmc_wait pins.  But in my external device there is no provision for wait monitoring... so can i use gpmc_wait pin with my one of the gpio pin  ?

Thank you,

No, GPMC_WAIT is an input signal which is controlled by the external memory. If your memory doesn't output this signal you cannot use it. I would suggest checking your GPMC timings with an oscilloscope and verifying against the memory datasheet timing requirements.

Hi,

we are setting the gpmc_ad pins as output while writing data into SRAM and while reading we are changing the gpmc_ad pin as input pull up and after making input pullup we are expecting the value as 0xFF. But we are getting the finally written value... so what is the mode  we have to select while reading and writing in to SRAM.......

Thank you,

You have to pinmux the GPMC_AD pins to GPMC mode with Rxactive once only, when you initialize the GPMC. It's completely unnecessary to change pinmux on every R/W access.

Thank you.... we will try that...