• State
  • Locked Locked
  • Replies 9 replies
  • Subscribers 52 subscribers
  • Views 2368 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.

32Mhz clock not working on CC2541 prototype

Jay Buggy
Prodigy 125 points
Other Parts Discussed in Thread: CC2541, LM92, TMP006, CC-DEBUGGER

Hi, We have built a prototype board (Based on sensor tag design) with CC2541 and a couple of temperature sensors (TMP006, LM92) on it.

CC-Debugger can see the CC2541, and also program it.  But we are not able to see the clock coming out of the crystal.  

We are using 32MHz TXC crystal (http://www.txccrystal.com/images/pdf/7b-accuracy.pdf).  Crystal has a load capacitance of 10pF; and Equivalent Seires Resistance (ESR) of 40 ohm. 

We have tried 12pF, 18pF, 22pF on leg capacitance.  

[Based on the formula C1*C2 / C1+C2; and with TI recommends, I think we covered the range on leg capacitance]

AVDDx, DVDD were at 2.4V.  No clock is seen on Pin 22/23 (XOSC_Q1/XOSC_Q2).

Please help see if this is not the right crystal, or if there is a recommended list of crystals with correct leg capacitance that will work with CC2541.

From the software standpoint, after downloading and starting execution, code can execute write to SLEEPCMD :  

    SLEEPCMD &= ~OSC_PD;     /* start 16MHz RCOSC & 32MHz XOSC */

but after that it is not able to get XOSC_STB in SLEEPSTA register.  Basically gets stuck in loop at 

   while(!(SLEEPSTA & XOSC_STB));

Value of SLEEPSTA is 0x2C.

Appreciate your help!

Thank you very much.

Jay.

  • 0
    TI__Guru 56590 points

    Hello Jay,

    From the specs it seems like it should work. can show me the parts of the schematic and layout that is related to the crystals?

    Here is a list of recommended crystals:

    http://processors.wiki.ti.com/index.php/CC_Crystals

  • 0
    TI__Guru 56590 points

    BTW: Have you installed a 32 kHz XTAL as well?

  • 0
    TI__Intellectual 1840 points

    Just to add to Eirik's suggestion,

    As per your mail, you mention that the CC Debugger is able to recognise the CC2541 , and you were also able to program it.

    So, the 32Mhz clock must be ticking.

    And since you also mention that it is stuck at the SLEEPCMD section, it likely points to the 32K crystal section of the HW.

    Please share the HW snapshot to support further.

    Also, let us know the BLE stack version and IAR version that you are currently using for this development.

    Regards,

    Vijay

  • 0 in reply to Vijayasarathy Shastri
    Mastermind 8695 points

    The chip will run with the 16MHz clock as the system clock. I have ran the chip with no crystals. It didn't do much, but i executed code

  • 0 in reply to Eirik V
    Prodigy 125 points

    Hello Eirik, Vijay, Thank you for your reply!  Here is the part of the schematic.

    We haven't tried any other crystal yet, but for time being replaced the 32MHz crystal with a oscillator.  And things started working fine.  Yes, we do have a 32KHz XTAL connected as well.

    IAR version we use is 8.30.2; and BLE stack version is 1.4.0.

    Thank you very much!

    Jay.

  • 0 in reply to Jay Buggy
    Mastermind 8695 points

    The 32MHz part number you referenced in your first post is a 4 pin package. The 32MHz part in your schematic only shows 2 pins. Explain the discrepancy.

    Could you provide the part # of your 32.7KHz crystal?

    Other flaws in your design can adversely impact the clock circuitry. Are you supplying > 2.1 volts to all the necessary pins? Do those pins have nearby decoupling capacitors?

  • 0 in reply to Jay Buggy
    TI__Guru 56590 points

    Peter:

    There is four pins, two of them (2&4) are grounded.

    Jay:

    Could you try the following to help us dig further:

    • Try to test an extended range on the load capacitance. Test down to 6 pF and up to the 30 pF range.
    • Set the following define in you IAR OSC32K_CRYSTAL_INSTALLED=FALSE:
      • Just to rule out the 32 kHz from the root cause, but since you where able to run it with an external oscillator this is probably not the root cause anyway...
    • Try to use the PER test in SmartRFStudio:
      • If you can transmit and receive packets with your design this means that the 32 MHz oscillator is working as this is needed to source the VCO in the radio that creates the RF frequencies.
    • Try to replace the 32 MHz crystal with a different of the same type and also try another one if possible.
    • Can you show us the PCB layout around your crystal and traces going the the XTAL pins on the CC2541?
  • 0 in reply to Eirik V
    Prodigy 125 points

    Hi Eirik, Peter, folks,

    I sincerely apologize for the delay in this.  The part indicated in my previous email [32MHz TXC crystal (http://www.txccrystal.com/images/pdf/7b-accuracy.pdf). ] was NOT the part used on the board.  There was a error on the side of procurer, and he got a wrong part.  For now, we are using the oscillator; and I will definitely get back to you on update with the crystal use.

    Apologies again!

    Thank you.

    Jay.

  • 0 in reply to Jay Buggy
    TI__Guru 56590 points

    It happens :), 

    Hopefully it will work well when you get the right part.