LPC844 clock out

[tyassin1]

Hi 

I m trying a very simple example, to get the CLKOUT to work on a LPC844.

I am using the below SDK

I make a project and use the code below to output the MAINCLK to PIO0_24:

SWM0->PINASSIGN_DATA[11] &= ~(0xFF<<8);
SWM0->PINASSIGN_DATA[11] |= (24<<8);
SYSCON->CLKOUTSEL = 1;
SYSCON->CLKOUTDIV = 1;

But nothing happens on the pin. I am missing something?

Br

Thomas

[tyassin1]

Hi,

Thank you for feedback.

First of all.....it works now

The missing part was the activation of the SWM: SYSCON->SYSAHBCLKCTRL0|=1<<7; 

But I had thought about it and looking in the manual:

It states that it is enabled from reboot or am I missing something?

Br

Thomas

[xiangjun_rong]

Hi, Thomas,

It is good new that it works well. Regarding the SWM bit which is set in default after reset based on the Table 147. System clock control 0 register, maybe it is documentation error, the bit SWM is cleared in default after reset.

BR

XiangJun Rong

[tyassin1]

Hi 

Maybe there is no error after all. 

When I look in the user manual, then I don't think table 147 is the right table you refer too. I refer to table 146 (SYSAHBCLKCTRL0).

But continuing to table 148 (PRESETCTRL0) (maybe also the one you meant instead of table 147), then I can see that SWM is reset by default, but this can be changed in this register.

So I guess that SYSAHBCLKCTRL0 can be changed on the fly in the code and PRESETCTRL0 is a startup thing when it boots.

Br

Thomas

[xiangjun_rong · Accepted solution]

Hi, Thomas,

How about using the code like:

SYSCON->SYSAHBCLKCTRL0|=1<<7; //or //SYSCON->SYSAHBCLKCTRL[0]|=1<<7;

SWM0->PINASSIGN_DATA[11] &= ~(0xFF<<8);
SWM0->PINASSIGN_DATA[11] |= (24<<8);
SYSCON->CLKOUTSEL = 1;
SYS...

Hope it can help you

BR

XiangJun Rong