clock problems

[bleumers_j]

Posted on July 09, 2003 at 14:06

clock problems

[bleumers_j]

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.

[stephanie]

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)?

[drumfirex]

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

[bleumers_j]

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

[drumfirex]

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

[stephanie]

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