Hardware trigger: ADC start on CT16B0_MAT0 doesnt work...

[berndsirozynski]

Problem:

Hardware trigger: ADC start on CT16B0_MAT0 doesnt work...

Description in Usermanual UM10524

LPC1315/16/17/45/46/47 User manual

Rev. 4 — 12 March 2013

and here Page 356 of 416

Optional conversion on transition on input pin or Timer Match signal.

Page 359 of 416

Note that this does not require that the timer match function appear on a device pin

Hello,

I have programmed the Timer 0 to a match on every Millisecond.

To ensurte that it works, i toggle a LED in the Interrupt funktion.

i looked to the Oscilloscope, all is fine.

in this function i started per software the ADC with writing 0x01 to the START bits

in ADC_CR register. The ADC conversion starts and after conversion i get a ADC Interrupt.

it works correct.

Now is want to start the ADC automatically on match,

so i wrote 0x06  (start conversion on CT16B0_MAT0) to the START bits. 

but the ADC never startet on match.

i have spend a lot of time to find the problem, but cant find it.

Maybe there is a Problem in the CHIP ? or i misunderstood the User manual ?

Siro

[jeremyzhou]

Hi Siro,

Thank you for your interest in NXP Semiconductor products and opportunity to serve you.

I was wondering if you can share the demo, then I will replicate the issue on my site.

I think this way can accelerate the investigation of the issue.

I'm looking forward to your reply.
Have a great day,
Ping

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[berndsirozynski]

Hello,

thanks for your answer jeremyzhou,

the night is long and i have spend lot of time and found the behavior

i must set the EMC (External Match Register) to "toggle mode" EMC0 = 0x03

but know:  in this way my ADC interrupt works at a "doubled time" of MATCH control.

These "external" match bit can connected to the ADC start.

now the adu triggerd in hardware at the doubled samplerate from Timer0 Match Value.

dont set the EMC to 0x1 (clear) or 0x02 (set) then you get only one Interrupt

this depends of the Bit "EDGE" Bit in ADC_CR register.

Siro

[berndsirozynski]

Hello,

thanks for your answer,

the night is long and i have spend lot of time and found the behavior:

i must set the EMC (External Match Register) to "toggle mode" EMC0 = 0x03

but know:  in this way my ADC interrupt works at a "doubled time" of MATCH control.

These "external" match bit can connected to the ADC start.

now the adu triggerd in hardware at the double time from Timer0 Match Value.

dont set the EMC to 0x1 (clear) or 0x02 (set) then you get only one Interrupt

this depends of the Bit "EDGE" Bit in ADC_CR register.

you dont need to configure the harware pin to Macth out, but you MUST set the EMC0 to toggle mode.

have a good weekend.

Siro