I have read the ST app note about crystal oscillators and I am concerned about the drive level. Before reading this app note, I chose the TXC 7M series crystals for its small size and reasonable cost. In the datasheet, its drive level is specified between 1 µW and 50 µW. Unfortunately, I do not have the equipment to measure the drive level in place on the board. Is there some advice you could give me here? Is the 7M series likely to work properly without a series resistor or do I need to change my design?