topic Re: 9S08DZ - crystal problem in 8-bit Microcontrollers

9S08DZ - crystal problem

grimble — Mon, 15 Sep 2008 01:15:39 GMT

Hi,

I develop my own board for master thesis. It's based on MC9S08DZ60. Initially I build very simple board (power supply, BDM programming head, one LED). Simple blinking LED program worked fine. I use witztronics.com debugger and CodeWarrior 6.2

Next step, was to enable precise clock. I used 12Mhz crystal and schematics from datasheet. Rs resistor was omitted because it should be used only with low frequency crystals. Board schematics is attached.

After power up, Code Warrior debugger tells me that it can't load diagnostics algorithm to target system, the chip is locked or derivative selected wrong. Few 'OK's later I can see that debuger detects target speed change and uC resets itself endless.

I removed crystal and related resistors and capacitors. It seems that I damaged uC because still can't program it.

I tried capacitors 18pF, 22pF, 27pF, 33pF, 39pF and 47pF(ceramic, 5%, smd 1206). Crystal 6MHz and 12MHz. Rf resistor 1MOhm and 3,3MOhm

Finally my question is: what might cause the problem? should I use Rs resistor?

Bartek

Re: 9S08DZ - crystal problem

peg — Mon, 15 Sep 2008 06:05:33 GMT

Hello and welcome to the fora, grimble

Simply adding the hardware for an external crystal should have no effect whatsoever.
Presumably you are using a blank device or the one you were using previously in internal oscillator mode. Unless you get the device going and then switch it to external mode the extra parts just sit there and do nothing. I think you have some other problem here.

Re: 9S08DZ - crystal problem

erooll — Mon, 15 Sep 2008 22:04:46 GMT

Hi.

Try change Rf by one of 10M, also make sure that you are using External oscilator as clock source, I suggest use Device initialization on CW in order to set clock source settings.