Posted on March 26, 2004 at 05:08Hi
Your option bytes settings look okay, but I wouldn't use the HS setting unless you're really using a ceramic resonator. The external clock CLK_IN on OSC1 is the correct source for a quartz crystal.
However I'm assuming that your selection isn't working, otherwise you wouldn't be asking!
Perhap you've made the same mistake as I did?
The default CLK_IN source is via PB4 (see option byte 0, bits [4:6]). After a power-on-reset the MCU is looking for your 8MHz clock on PB4 and not at the OSC1 and OCS2 pins. So you need to modify the option bytes before swapping the clock source. i.e.
(1) Connect your 8MHz clock to PB4.
(2) Modify the option bytes, via the STVDB7.
[At this point the ICC comms might fail, as the source clock is lost.]
(3) Re-wire the 8MHz clock to the OSC1 and OCS2 pins.
(4) Re-start the STVDB7 project /debugger.
[This should swap the clock source and re-establsh the ICC comms.]
Regards
Steve.
[ This message was edited by: Steveboy on 26-03-2004 09:45 ]
