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I am quite new to Infineon. We are using the XMC1100 series (38pin). For timing acuracy I need to clock a timer from an external crystal however I can see no obvious way to do this as the clock inputs do not seem to to come out to external pins. Also I am struggling to understand the difference between say between CC41 and CCU4x.OUT1 - should this not be called CC41.OUT?
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Hi Martoon,

There is no external clock input for the timer (CCU4).
Hence, you can only improve the accuracy by calibrating the internal oscillator.
You can find more details on the device guide “DEV_XMC1000_Oscillator_Handling_v1_1”.

For the naming, CC41 referring to the Timer Slice 1 in the CCU4 module.
There are 4 timer slices in one CCU4 module (CCU40).
Hence, in CCU40, you will have CC40, CC41, CC42 and CC43

For CC4x.OUT, that's refers to the output pin of the timer slice.
Output pin for CC40 is called CC40.OUT, output for CC41 is called CC41.OUT and so on..

I Hope this is more clearer to you now.
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Hi Jackson,

Thanks for replying but you have confused me more.

First in XMC1100_eratasheet_v1_2_2013_11 it seems to imply you can use an external clock as long as you divide it by at least 2 (section CCU_AI.005) but it seems that every timer would then run off the exterernal clock and not just one! Maybe there is a way I could count external clocks on one of the inputs.

Also the way you have named the timer outputs is perfectly logical but that is not how they are named in your datasheets such as the reference manual in there they called things like CCUx.OUT1?
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Hi Martoon,

Sorry, is my mistake.
You can clock in the external clock via ERU module.
You can check connected ERU signal for the external clock from the Interconnect sub-chapter in the CCU4 Chapter.
But please take note that this clock is not directly clocking the module itself.
Basically, the PCLK will sampled the external clock and using it as the module clock.
Hence, if the external clock is slow, it is fine but if the clock signal is higher than PCLK, it is not possible.
And because the external clock is sampled by PCLK, it could cause some jitter if the external clock is just slightly slower than the PCLK.
Hope you get what I mean.

For the timer, if u see CCU4x, this refers to the module. if you only see CC4x(without 'U'), then this refers to the timer slice.
For the output pin, CCU40.OUT0 will refers to output pin for timer slice 0, CCU40.OUT1 will refers to output pin for timer slice 1 and so on..