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Maximum Frequency of ACLK_EIM_SLOW_CLK_ROOT for i.MX6QP

Question asked by Takayuki Ishii on Nov 13, 2018
Latest reply on Nov 27, 2018 by Takayuki Ishii

Hello community,


I received this question form my customer.

So I'm searching past thread of it.

But I can not find an answer for i.MX6QuadPlus.

And different 2 pattern comment for i.MX6DL and i.MX6Quad, I can found.


1) Maximum Frequency of ACLK_EIM_SLOW_CLK_ROOT = 104MHz

Maximum Frequency of ACLK_EIM_SLOW_CLK_ROOT 


2) Maximum Frequency of ACLK_EIM_SLOW_CLK_ROOT= 133MHz for asynchronous mode.

    104MHz for synchronous mode.

i.MX6DQ EIM clock for asynchronous access. 


    or in datasheet for i.MX6SDL

4.9.3 External Interface Module (EIM)
The following subsections provide information on the EIM. Maximum operating frequency for EIM data
transfer is 104 MHz. Two system clocks are used with the EIM:
• ACLK_EIM_SLOW_CLK_ROOT is used to clock the EIM module.
The maximum frequency for CLK_EIM_SLOW_CLK_ROOT is 132 MHz.
• ACLK_EXSC is also used when the EIM is in synchronous mode.
The maximum frequency for ACLK_EXSC is 104 MHz.
Timing parameters in this section that are given as a function of register settings.


Q1. Which is a correct answer of maximum frequency of ACLK_EIM_SLOW_CLK_ROOT for i.MX6QP?

Q2. In "Table 8-4. Normal frequency clocks configuration" at section "8.4.3 Clocks at boot time" of

      IMX6DQPRM rev 2 it say that ROM boot loader is set aclk_eim_slow_clk_root = 132MHz.

      The other hand, u-boot for Linux BSP is setting ACLK_EIM_SLOW_CLK_ROOT=132MHz too.

      Is it a timing violation setting for i.MX6DQ and i.MX6DQP? and not recommended to use it?

     I think it is OK for i.MX6SDL because it say that maximum frequency of ACLK_EIM_SLOW_CLK_ROOT=132MHz

     in their datasheet.


Best regards,