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bleumers_j
Visitor II
July 9, 2003
Question

clock problems

  • July 9, 2003
  • 6 replies
  • 1380 views
Posted on July 09, 2003 at 14:06

clock problems

    This topic has been closed for replies.

    6 replies

    B
    bleumers_jAuthor
    Visitor II
    June 27, 2003
    Posted on June 27, 2003 at 09:30

    Hello,

    When i mount an 8MHz crystal on my board with 2x 47pF to ground and i switch off the RC-oscillator, the ST7 seems to 'die'.

    I can't read or write anymore with the ST-Stick and the program doesn't run.

    When i put the scope on the crystal, the clock doesn't run.

    Anyone an idea what's going wrong???

    Regards.
    S
    stephanie
    Visitor II
    July 2, 2003
    Posted on July 02, 2003 at 07:46

    What is your device? Did you configure the right oscillator range in option bytes? Which ICP did you choose in STVP7 (OPT disable or enable)?

    D
    drumfirex
    Visitor II
    July 2, 2003
    Posted on July 02, 2003 at 09:23

    I never used RC-oscillator (not internal nor external) so I'm not sure abuot the following procedure...

    I'm programming on ST72324 using inDart.

    If you use a crystal you should set ''Resonator Oscillator'' in the option bytes.

    You should program the option bytes when the uC is ''alive'', so:

    - switch on RC-oscillator

    - reprogram option bytes with ''Resonator Oscillator''

    - connect the crystal and switch off the RC-oscillator

    In the 72324 datasheet, typical values of capacitors (for a 8MHz xtal) are 33pF each.

    I hope that can help,

    Patrik
    B
    bleumers_jAuthor
    Visitor II
    July 2, 2003
    Posted on July 02, 2003 at 13:38

    Hi,

    Programming is OPT enable. Had the problem with the st7lite29 and with the st7dali. I'm using an 8MHz crystall.

    I choose the 4/8MHz Medium Speed resonator, program this. After doing this (like Patrik told) i switch off the internal oscillator and program the option bytes for a second time. After this the IC died...

    I must do something wrong but i can't figure out what.

    Greets

    D
    drumfirex
    Visitor II
    July 3, 2003
    Posted on July 03, 2003 at 09:32

    The signal on the crystal is present only if the option bytes are set correctly. I set two option bytes as follow:

    - [OSCRANGE] - Oscillator Range Selection: ''MS: 4-8MHz''

    - [OSCTYPE] - Oscillator Type Slection: ''Resonator Oscillator''

    Bye,

    Patrik
    S
    stephanie
    Visitor II
    July 9, 2003
    Posted on July 09, 2003 at 14:06

    The right way to proceed is the following one:

    * as by default, the clock is internal RC, program your Flash

    * then the option byte (no matter if the quartz is already on the appli board, it will be ignored when configured in internal RC thanks to internal switches): Resonnator oscillator, oscillator mid-range, internal RC off + the other options

    * remove your ICC cable

    * make a reset of the MCU
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