LPC1769, ADC with NXP CMSIS

lpcware — Thu, 16 Jun 2016 02:17:29 GMT

Content originally posted in LPCWare by JojoS on Sun Mar 11 08:50:19 MST 2012
Hi,
I'm playing with the LPCXpresso and have used the webserver RTOSDemo_RDB1768. I have modified the sources to use the ADC with interrups.
Somehow it worked, but the converson rate did not match my setting in ADC_init(); I found there is a problem with setting a low sampling rate: then the divider becomes >255 and writes in other control bits than the estimated divider bits. The cmsis driver should check this, is there any address to report such problems?
I found also that there is a newer driver lib availible at NXP with improved clock setting. It takes into account that a conversion takes 65 clocks. But there was another little bug: the init function reads the cpu clock:

ADCPClk = CLKPWR_GetPCLK(CLKPWR_PCLKSEL_ADC);

In my case I used some (none cmsis) code to change the clock to 120 MHz, but the GetPCLK returned 100 MHz. After adding a ClockUpdate it worked fine:

 
SystemCoreClockUpdate();
 
 
ADCPClk = CLKPWR_GetPCLK(CLKPWR_PCLKSEL_ADC);

Maybe it is better to include the clock update function in the GetPCLK() to make sure to use the correct clock? I guess there are other places in the code where this can lead to wrong clock settings.

And another question: I found the updated CMSIS driver lib at NXP, but now I replaced only the adc code. I was not successful to create a new project in the Code Red IDE that creates a whole new CMSIS 2.0+drivers lib. Can anyone describe the necessary steps to create this project? In the NXP download are no project files for the CR environment.

LPCXpresso IDE中的主题 LPC1769, ADC with NXP CMSIS

LPC1769, ADC with NXP CMSIS