Timer use for LPC11U37H: Is it possibel to generate an 8HMz and an 1MHz Output Signal's with CT16B0 MAT0 an MAT1 Output?

[klakow]

I use an OM130074 Evaluation board for pre development the Software for a target system that is currently in production.

I will use a 16-Bit Timer Channel 0 to gennerate to signals.

My base main board frequency will be running with 48MHz (USB Request conditions).

From that the first step is working, i can generate an signal from 16MHz (maximum), to my lowest frequency for the application is 4Mhz.

For this i use Port0_9.

An second Signal musts generate an Signal from 2MHz down to 500kHz and shut use Port0_8.

Is it possible with one timer?

[klakow]

For my understanding it is not possible. Both Pins use the same Timer, CT16B0, it is not possible because it is not possible to connect (by an example), the internal Signal of Prescale Counter result to one of the Match outputs and use the other Match register together with TC-Register with the option one more Match Register to generate an 50:50 tau of the high-low Time of the Signal.

This will would be a good solution to generate two different frequencies with one timer.

Now i will use CT16B0 and CT16B1 together with to Match outputs.

In my application i need Signal that shift (clock) signal to generate 8-shiftet Clocks with an 74HC164 logic Chip.

The Frequency relation is Shift_Signal=BaseClock*8.

@NXP: This function will be easy implementation with small chip resources, if you use External Match Register EMCx Option 0x0, not continue to do nothing, but rather use internal Clock from Prescale Counter connect direct to an Match Output.

Best regards, Ulrich Klakow from Germany

[klakow]

If an responsible member from NXP read this,

if you make an Chip design you can also at an other mode mode for Timer use.

Instead of PWM, use an Base counting Value for the lowest Frequency, and use other Match Counter Register together with an one byte Modulo Register.

In this case (new operation mode), the TC Register compare not direct with the value, but make:

if(( TC & MatchModuleByte)==MatchRegister) set MatchOutput

else reset MatchOutput.

This will be very help full to generate Clocks for synchronies multiple switched power supplies to reduce EMI.

Best regards, Ulrich Klakow

[jeremyzhou]

Hi Ulrich Klakow,

Thanks for your reply.

I think the 17.7.13 Rules for single edge controlled PWM outputs episode is able to implement your purpose with the hardware feature

If I missed some things, pleas pointing out.

Have a great day,
TIC

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[jeremyzhou · Accepted solution]

Hi Ulrich Klakow,

Sorry, I made a mistake, one CT16Bn can't generate PWMs with different frequencies, and it needs to consumes two CT16B to implement it.

Hope this is clear.
Have a great day,
TIC

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[jeremyzhou]

Hi Ulrich Klakow,

Thank you for your interest in NXP Semiconductor products and 

for the opportunity to serve you.

1) An second Signal musts generate an Signal from 2MHz down to 500kHz and shut use Port0_8.

Is it possible with one timer?

-- Yes, it's available

Have a great day,

TIC

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Note: If this post answers your question, please click the Correct Answer button. Thank you!
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