Linux/PROCESSOR-SDK-AM335X: DDR2 EMIF clock

ay park

Prodigy 145 points

Part Number: PROCESSOR-SDK-AM335X

Tool/software: Linux

Hi, All~!

I'm confuse of EMIF Clock and DDR Clock.

My Source Clock is 24MHz of OSC0_in Clock.

Spec said that ocp_clock(interface clock)'s max freq is 200Mhz.

And m_clk(EMIF functional clock)'s max freq is 100Mhz.

But, I'm confusing about ddr_clock and EMIF clock.

What's meaning of EMIF clock?

Is it different of DDR clock and EMIF clock?

Thanks in Advance.

over 8 years ago

0 Biser Gatchev-XID over 8 years ago

TI__Guru**** 393215 points

Hi,

DDR clock is the external clock provided by the processor to the DDR memory. EMIF functional clock is the internal clock for the EMIF peripheral.

0 ay park over 8 years ago in reply to Biser Gatchev-XID

Prodigy 145 points

Thank you for your help.
I have one more question about “m_clk and cmd0_dfi_clk”.

Table 7-95. EMIF Clock Signals

Clock signal	Max Freq	Reference Source	Comments
ocp_clk (Interface clock)	200 Mhz	CORE_CLKOUTM4	pd_per_l3_gclk From PRCM
m_clk (EMIF functional clk)	100 Mhz	DDR PLL CLKOUT/2	pd_per_emif_gclk From PRCM
cmd0_dfi_clk cmd1_dfi_clk cmd2_dfi_clk data0_dfi_clk data1_dfi_clk (Macro clocks)	200 Mhz	DDR PLL CLKOUT	clkout_po From DDR PLL

Figure 8-13. DDR PLL Structure

(http://i.imgur.com/LUU4N0q.png)

Is the DDR CLOCK derived from DDR PLL CLKOUT?

If the frequency for DDR clock is 266Mhz that the CLKOUT is to expected to 266Mhz.
So I think cmd0_dfi_clk is also expected to 266Mhz, and EMIF M_CLK is expected to 133MHz.
But the spec said to me, Max EMIF M_CLK is 100Mhz. If the DDR CLK is 266Mhz, I think EMIF m_clock is 133MHz, though.

I want to know what the true values of EMIF m_clk and cmd0_dfi_clk are?

0 Biser Gatchev-XID over 8 years ago in reply to ay park

TI__Guru**** 393215 points

The TRM you are reading is old. Please download the current TRM (http://www.ti.com/lit/ug/spruh73o/spruh73o.pdf).

0 ay park over 8 years ago in reply to Biser Gatchev-XID

Prodigy 145 points

Thanks a lot for your help.

SAMSUNG K4T1G084QF-BCE7 DDR(what I want to use) has got the speed ‘DDR2-800 5-5-5’.

DDR PDF Link

But, I’ve checked that AM335x use “DDR2-532, DDR3-800” at “SPRS717”.

Can I use the K4T1G084QF-BCE7 DDR by DDR2-800 speed at am335x?

0 Biser Gatchev-XID over 8 years ago in reply to ay park

TI__Guru**** 393215 points

The maximum DDR clock frequency for DDR2 is 266MHz. The minimum speed grade requirement for DDR2 memory is DDR2-533. Your DDR2-800 is better that this requirement, therefore you can use it.

0 Biser Gatchev-XID over 8 years ago in reply to Biser Gatchev-XID

TI__Guru**** 393215 points

Note that you cannot exceed the 266MHz limit. Your memory may be DDR2-800, but it will work at DDR2-533 speed.

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Linux/PROCESSOR-SDK-AM335X: DDR2 EMIF clock