• State Resolved
  • Locked Locked
  • Replies 4 replies
  • Subscribers 56 subscribers
  • Views 503 views
  • Users 0 members are here
Support feedback
Options
Options
Related

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.

CC2530: CC2530 clock source

Manh Tuyen Ta
Prodigy 100 points
Part Number: CC2530


Hi,

I have been working on CC2530 as a newbie.I am confusing the difference between clock system source (32MHz XOSC and 16MHz RCOSC) and 32kHz oscillators (32kHz XOSC and 32kHZ RCOSC).

What is the main purpose of the 32kHz oscillators and its operations when switching from 16MHz RCOSC to 32MHz XOSC?

I have tried the CC253x-4x User guide but I still do not get the point.

Thank you for your attentions.

  • 0
    Guru 735695 points
    The purpose of 32kHz is major for sleeping mode of CC2530. When CC2530 isn't under sleeping mode, it would use 32kHz XOSC or 32kHZ RCOSC.
  • 0 in reply to YiKai Chen
    Prodigy 100 points
    Yikai Chen,
    What about its operation when a switch from 16MHz RCOSC to 32MHz XOSC?
    Could you explain more in detail the quote "When system clock is changed from the 16-MHz RCOSC to the 32-MHz XOSC (CLKCONCMD.OSC from 1 to 0), calibration of the 32-kHz RCOSC starts up and is performed once if the 32-kHz RCOSC is selected." coming from the User guide.
    What does "calibration" mean in this concept?
    Thank you,
  • 0 in reply to Manh Tuyen Ta
    Guru 735695 points
    I am not very clear about this 16-MHz RCOSC to the 32-MHz XOS thing and hope someone from TI can help to explain this.
  • 0 in reply to YiKai Chen
    TI__Guru* 87001 points
    Please refer to Table 4-1 in the User guide. There you see that in Active or IDLE you will have both HF oscillators and LF Oscillators running. The 32 MHz crystal is necessary for Radio operation. The 16 MHz RCOSC can be used otherwise.
    In PM modes you will have the LF oscillators running. If you do not require very high accuracy, you do not need a 32 kHz crystal in your design.
    An RC OSC is not very accurate if not calibrated. The way the device is designed is that whenever the 32 MHz crystal is started, the LF RCOSC is calibrated to have it run on a frequency close to 32.753 kHz (the LF RCOSC frequency is the 32 MHz crystal frequency divided by 977 and the accuracy after calibration is +-0.2 %)