LPC power profile API & Remark

[yoshiyukiokada]

I'm using LPC812.

Can I change the value of SYSAHBCLKDIV from "1" to "12" after I call set_power routine with low current mode?

I'd like to use power profile API, set_power routine. 

According to a LPC81x Users manual, SYSAHBBLKDIV should be kept "1" while using the set_power routine as below, 

"Remark: Use the set_power routine with SYSAHBCLKDIV = 1 (System clock divider register, see Table 29 and Figure 47)."

On the other hand, I'd like to make system clock 1MHz without using System PLL to pursue low power consumption. Therefore, I set the clock configuration as below;

Main clock :12MHz ( drive from IRC oscillator) 

System clock : 1MHz ( main clock is divided into twelve, SYSAHBCLKDIV = 12 )

I'd like to change the value of SYSAHBCLKDIV from "12" to "1" after I call set_power routine, however, I'm afraid it will conflicts with the Remark.

Best regards,

[yoshiyukiokada]

Hi Kerry,

I've tried it with my lpc812 xpressso board and confirmed that the current consumption decreased by 200uA.

However, I'm not sure weather my trial is appropriate or not since I couldn't fined any documents guarantee my way.

Best regards

Yoshiyuki 

[kerryzhou · Accepted solution]

Hi Yoshiyuki Okada,

   Test result is the most useful guarantee, if your current consumption is really decreased, and your code function is working OK, it is really useful. Document won't write every details.

   But, if you meet the problem in the future, just post the question, and let us know.

Have a great day,
Kerry

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[kerryzhou]

Hi Yoshiyuki Okada,

    After you call set_power , I think you can set SYSAHBCLKDIV from 1 to 12.

   You can try it on your side, if you meet any question after you modify it, please let me know!

Have a great day,
kerry

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