What should be considered when USB device can not be recognized?
Users can check the following aspects:
1． USB device power supply is between 4.4V and 5.25V;
2． D+, D- cable is connected properly;
3． Full-speed devices D+ pulled up 1.5K resistor to Vreg33, low-speed devices D- pulled up 1.5K resistor to Vreg33. Sonix Flash IC not need 1.5K pull-up resistor, but there need a capacitance connected to the ground, low speed 4.7uf, full speed 1uf;
4． The external connected crystal matchs the crystal options;
5． Whether the resistance or capacitance parameters series connected to ground on D+, D- referred to reference circuit that Sonix provided;
1． USB device power supply is between 4.4V and 5.25V;
2． D+, D- cable is connected properly;
3． Full-speed devices D+ pulled up 1.5K resistor to Vreg33, low-speed devices D- pulled up 1.5K resistor to Vreg33. Sonix Flash IC not need 1.5K pull-up resistor, but there need a capacitance connected to the ground, low speed 4.7uf, full speed 1uf;
4． The external connected crystal matchs the crystal options;
5． Whether the resistance or capacitance parameters series connected to ground on D+, D- referred to reference circuit that Sonix provided;