stm32f429i-discovery SDRAM HAL driver assistance

[monomonster]

Posted on July 15, 2015 at 02:17

I can't seem to find a single example using the HAL driver. I am wondering what is the suggested solution for address management for the SDRAM and also, what is the start address anyway and how do you know?

#hal #!stm32f4-disco #sdram

[Tesla DeLorean]

Posted on July 15, 2015 at 05:37

It's a secondary bank SDRAM so it lives at 0xD0000000 on the DISCO. The EVAL series board (STM324x9I-EVAL) it's the primary bank at 0xC0000000

For HAL code perhaps review some of the examples might help

STM32Cube_FW_F4_V1.3.0\Projects\STM32F429I-Discovery\Examples\FMC\FMC_SDRAM\Src\main.c

[monomonster]

Posted on July 15, 2015 at 11:07

Thanks for the reply.

So according to the settings I can see in the example, the row address is 12bit, the column address is 8bit and there are 4 banks. 16 * 2^12 * 2^8 * 4 = 67108864 right?

I've actually looked at that example, it does not use the read and write functions from the HAL driver but rather writes directly using a pointer to the memory. But that's OK.

In order to calculate the address the bank address (0xD0000000) is multiplied by WRITEÖ¹_READÖ¹_ADDR (0x800) and by uwIndex (32bit) multiplied by 4.

So this bank address is the starting address of the SDRAM, right?

I'm not sure what is the write_read_address?

I'm also not sure why uwIndex is multiplied by 4?

Last, how do you know what is the start address for the external RAM? It is larger than the physical address that can be addressed using the available bits.

[Tesla DeLorean]

Posted on July 15, 2015 at 14:12

I've basically read and understood the manuals.

The Cortex-M4 has a 32-bit address bus, giving it access to a 4GB address space.

The SDRAM lives *within* this address space, the chip select in the logic surrounding the core recognizes the 256KB region between 0xD0000000..0xDFFFFFFF. The logic basically decodes, recognizes, the 0xD value in the high order 4-bits of the address on the bus, and directs traffic to the FMC/SDRAM.

I'm not familiar with WRITE?_READ?_ADDR(), is suspect it multiplies by 4 because you're accessing 32-bit words, which take 4-bytes, which are separate but contiguous within the memory space.

The memory map is described in the FMC/FSMC section of the REFERENCE MANUAL