• State
  • Locked Locked
  • Replies 1 reply
  • Subscribers 30 subscribers
  • Views 430 views
  • Users 0 members are here
Support feedback
Options
Options
Similar topics

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

Unable to generate Comparator output on LM4F232H5QC

Gopi KL
Prodigy 35 points

Hi All

I am unable to get the Comparator working on the new Stellaris ARM Cortex. The following code was used to enable the same. Is there any other setting that I need to take care? or is is pre-production bug?

Thanks in advance. 

//COMP Int
ROM_SysCtlPeripheralEnable(SYSCTL_PERIPH_COMP0);
ROM_SysCtlPeripheralEnable(SYSCTL_PERIPH_COMP1);
ROM_SysCtlPeripheralEnable(SYSCTL_PERIPH_COMP2);
ROM_GPIOPinConfigure(GPIO_PF0_C0O);
ROM_GPIOPinConfigure(GPIO_PF1_C1O);
ROM_GPIOPinConfigure(GPIO_PF2_C2O);
ROM_GPIOPinTypeComparator(GPIO_PORTC_BASE, GPIO_PIN_4 | GPIO_PIN_5 | GPIO_PIN_6 | GPIO_PIN_7);
ROM_GPIOPinTypeComparator(GPIO_PORTG_BASE, GPIO_PIN_6 | GPIO_PIN_7);
ROM_GPIOPinTypeComparator(GPIO_PORTF_BASE, GPIO_PIN_0 | GPIO_PIN_1 | GPIO_PIN_2);
ROM_ComparatorConfigure(COMP_BASE, 0, COMP_TRIG_NONE | COMP_INT_RISE | COMP_ASRCP_PIN | COMP_OUTPUT_NORMAL);
ROM_ComparatorConfigure(COMP_BASE, 1, COMP_TRIG_NONE | COMP_INT_RISE | COMP_ASRCP_PIN | COMP_OUTPUT_NORMAL);
ROM_ComparatorConfigure(COMP_BASE, 2, COMP_TRIG_NONE | COMP_INT_RISE | COMP_ASRCP_PIN | COMP_OUTPUT_NORMAL);
ROM_ComparatorIntEnable(COMP_BASE, 0);
ROM_ComparatorIntEnable(COMP_BASE, 1);
ROM_ComparatorIntEnable(COMP_BASE, 2);
ROM_IntEnable(INT_COMP0);
ROM_IntEnable(INT_COMP1);
ROM_IntEnable(INT_COMP2);

-regards

KLG

  • 0
    Guru 47900 points

    Indeed - PF0 on the new M4F defaults into a special mode - and must be "unlocked" to enable its re-purpose - as you seek.  Fear not - procedure is explained w/in the MCU's datasheet - wise always to "RTFM."  You should know that our group - several months back - chose this exact pin for its comparator function - my report here exceeds the theoretical - we've actually re-purposed PF0 and use it in its comparator output mode.

    Ours is a 64 pin M4F - am concerned by your code's use of three comparators - wouldn't it be safer/easier/faster to bring up one comparator at a time?  (especially during checkout/verification - we think so - KISS)

    As always - quicker scan thru most recent errata is wise - often this errata provides the most current info on your chip.