topic Re: ADC Clock in LPCXpresso IDE

ADC Clock

lpcware — Thu, 16 Jun 2016 00:56:57 GMT

Content originally posted in LPCWare by Genesy on Thu Apr 11 03:00:00 MST 2013
From what I've seen, the APB bus is shared between all peripherals and it is related with the system clock. The ADC has a 8-bit divider which allows to obtain about 200KHz of ADC clock minimum. So if I want to get a clock frequency of 1kHz I'm forced to change the clock all the other peripheal that use, right?

Re: ADC Clock

lpcware — Thu, 16 Jun 2016 00:56:58 GMT

Content originally posted in LPCWare by R2D2 on Thu Apr 11 03:56:34 MST 2013
MCU :confused:

Re: ADC Clock

lpcware — Thu, 16 Jun 2016 00:56:58 GMT

Content originally posted in LPCWare by Genesy on Thu Apr 11 04:11:36 MST 2013
I'm sorry, I forgot to write it, but I think it's a general problem!
However it is a LPC11C14.

Thank you very much

Re: ADC Clock

lpcware — Thu, 16 Jun 2016 00:56:59 GMT

Content originally posted in LPCWare by R2D2 on Thu Apr 11 04:36:43 MST 2013

Quote: Genesy
but I think it's a general problem!

No, LPC17xx has a separate PCLK divider.

LPC11xx has ADC-CLKDIV (max. 256) with 11 clocks per conversion you get an overall division of 2816.

If you want to reach a special sample frequency like 1kHz you should use a match output (see AD0CR) to trigger your conversion :)

Re: ADC Clock

lpcware — Thu, 16 Jun 2016 00:57:00 GMT

Content originally posted in LPCWare by Genesy on Thu Apr 11 07:37:21 MST 2013

Quote: R2D2

If you want to reach a special sample frequency like 1kHz you should use a match output (see AD0CR) to trigger your conversion :)

I don't understand this point. Can you give me an example code?
Thank you very much

Re: ADC Clock

lpcware — Thu, 16 Jun 2016 00:57:00 GMT

Content originally posted in LPCWare by R2D2 on Thu Apr 11 08:11:04 MST 2013

Quote: Genesy
I don't understand this point.

Your timer can generate an 1kHz output signal (match output).

This signal can trigger your ADC conversion, so you can read your analog signal 1000 times per second with full ADC speed (4.5 MHz) :)

Quote: Genesy
Can you give me an example code?

No, somehow my Android Smartphone refuses to install LPCXpresso.

Re: ADC Clock

lpcware — Thu, 16 Jun 2016 00:57:01 GMT

Content originally posted in LPCWare by Genesy on Fri Apr 12 00:51:09 MST 2013

Quote: R2D2

This signal can trigger your ADC conversion, so you can read your analog signal 1000 times per second with full ADC speed (4.5 MHz) :)

But this operation improve the adc results and make them more stable?