topic Re: LPC11xx ADCInit confusion in LPC Microcontrollers

LPC11xx ADCInit confusion

lpcware — Wed, 15 Jun 2016 19:33:37 GMT

Content originally posted in LPCWare by corwinb on Tue Feb 12 10:01:01 MST 2013
The below code snippet is from the ADCInit function in the adc example. Don't understand why the first two instructions (&=, |=) exist. Why not just do the =? Is this just a copy and paste issue?

LPC_IOCON->R_PIO0_11 &= ~0x8F; /* ADC I/O config */
LPC_IOCON->R_PIO0_11 |= 0x02; /* ADC IN0 */
...
...
...
LPC_IOCON->R_PIO0_11 = 0x02;// Select AD0 pin function

Re: LPC11xx ADCInit confusion

lpcware — Wed, 15 Jun 2016 19:33:37 GMT

Content originally posted in LPCWare by tha on Tue Feb 12 13:54:37 MST 2013
This is mainly a coding choice. Some people like to clear all the bits first before setting them. This usually done for a just in case scenario.

Re: LPC11xx ADCInit confusion

lpcware — Wed, 15 Jun 2016 19:33:38 GMT

Content originally posted in LPCWare by avass on Sat Feb 16 00:42:14 MST 2013
"|=" makes sure you are only touching the bits you are setting.
"=" touches ALL the bits.

I personally use the |= to avoid accidental bit overwriting... It's a good practice and can save you tons of debugging...

Re: LPC11xx ADCInit confusion

lpcware — Wed, 15 Jun 2016 19:33:39 GMT

Content originally posted in LPCWare by corwinb on Sat Feb 16 09:32:47 MST 2013
Of course I understand specific bit manipulation. My original query was to question why the the example code cleared the range (&= ~), set specific bits (|=), and then did an assignment (=) all on the same register. I am new to the M0 and didn't know if there was some magical order things needed to be done. I can see clearly now. Thanks for the replies.