??? 09/01/06 19:13 Read: times |
#123533 - ALE probably won't help ... Responding to: ???'s previous message |
If the oscillator is not oscillating, it's unlikely the ALE will do anything.
What's at issue is the size of the load capacitors on the X1 and X2 pins. Whether the crystal is parallel- or series-resonant, the oscillation should be on the order of 20 MHz if it is a fundamental mode crystal. The circuit internal to the MCU should look, essentially, like a CMOS inverter with its input on X1 and output on X2 (It may be reversed on an ATMEL part, one never knows, but one pin is an input and the other is an output.) If it's not obvious whether or not it's an inverter, perhaps there's no power on the part (bent Vcc or Vss pin, for example.) Please answer carefully and completely the following questions. Are the load capacitors of the value specified in the datasheet for the device you're using? Is the supply voltage as specified in the datasheet? RE |