No DDR clock output

Discussion around products based on ARM Cortex-A5 core.

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mbucknall
Posts: 3
Joined: Fri Mar 16, 2018 10:42 pm

No DDR clock output

Fri Mar 16, 2018 10:59 pm

Hi,

I'm trying to write some initialisation code for a ATSAMA5D22 based board. I have the system clocks set up so that PCK = 498MHz and MCK = 124.5MHz.

I'm starting to write code for setting up the DDR memory interface (16-Bit DDRL). When I set DDRCK, by writing (1 << 2) to SCER in the PMC, I am not seeing any clock output on the DDR CK pins. Is further initialisation of the various MPDDRC registers required before the clock appears on the MPU's outputs?

The only restriction I can find in the reference manual is that DDR clock is not available when PMC_MCKR.MDIV = 0. I have MDIV set to 2 (divdie by 4).

Matt.
blue_z
Location: USA
Posts: 1763
Joined: Thu Apr 19, 2007 10:15 pm

Re: No DDR clock output

Mon Mar 19, 2018 8:57 pm

mbucknall wrote:I'm starting to write code for setting up the DDR memory interface (16-Bit DDRL).
You need to be more specific.
The SoC datasheet has three distinct procedures for low-power DDR[123] memory.

mbucknall wrote:Is further initialisation of the various MPDDRC registers required before the clock appears on the MPU's outputs?
Further than what?

Regards

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