topic Question about MPC8280's SDRAM machine in PowerQUICC Processors

Question about MPC8280's SDRAM machine

春新张 — Fri, 14 Jun 2013 07:44:06 GMT

Hi All,

Here is a project use MPC8280. I use SDRAM machine connect SDRAM(32M16A2).The SDRAM have 4 internal banks, 13 rows, and 10 columns.

I reference 《MPC8280RM Rev. 1, 12/2005》,11.4.5.2 SDRAM Address Multiplexing (SDAM and BSMA),but still have same

questions.

The reference book have examples,but all the examples are about SDRAM devices that have 4 internal banks, 12 rows, and 9 columns.

I copy the tables below.

My question is:

what is the meaning "-",is that I cann't use the pin?

for example I set SDMR[SDAM] = 100; Can I use A[14–15] for bank select pins?

Re: Question about MPC8280's SDRAM machine

lunminliang — Tue, 18 Jun 2013 09:59:10 GMT

I am afraid no, if setting SDAM to be "100", you can not use A14 and A15.

Re: Question about MPC8280's SDRAM machine

Bulat — Tue, 18 Jun 2013 11:26:44 GMT

"-" in the table means no address muxing for SDRAM's address signals during ACTIVATE command. This does not relate to the bank select signals, only to address ones. Muxing of bank select signals is defined by the xSDRAM[BSMA] field. The answer to your question: yes, you can use A[14–15] as bank selects if xSDRAM[BSMA] is properly set (BSMA=0b001).

Re: Question about MPC8280's SDRAM machine

alexander_yakov — Tue, 18 Jun 2013 12:23:44 GMT

Just to add to the Bulat' response - this setup "4 internal banks, 13 rows, and 10 columns" is described as Example 1 in application note AN2165 "MPC8260 SDRAM Support".

http://cache.freescale.com/files/32bit/doc/app_note/AN2165.pdf

Re: Question about MPC8280's SDRAM machine

lunminliang — Thu, 20 Jun 2013 01:50:03 GMT

Sorry, I made a mistake here. The Table 11-20 is for address multiplexing of row address, here "-" means for that "SDAM" configuration the physical address kine will not ouput mux address. A[14-15] can be used for bank select if configured by BSMA.