Pins and Connections

USB2SER Data Sheet, Rev. 0

Freescale Semiconductor

7

1.6

Reset and system initialization

The USB2SER has three reset sources:

•

Power-on Reset (POR)

•

External Reset Pin (RESET)

•

Software update Reset (Soft Reset)

System startup from any reset source starts with the crystal frequency auto-detection that takes 48 ms. After this step, the device

initializes the internal PLL to setup the internal clock to 48 MHz which will be used as the reference for the USB and UART to

work properly.

determine if the internal voltage regulator has to be enabled.

Figure 5. Clock and system initialization

1.7

VID and PID configuration

The USB2SER includes the functionality to modify the VID, PID, Product Description Strings and Power Descriptor Value.

The default parameters are:

•

VID — 15A2 Hex

•

PID — 005A Hex

•

Power Descriptor Value for 100 mA

•

Manufacturer string — FREESCALE SEMICONDUCTOR INC.

•

Product string — USB TO SERIAL

•

Serial number string — Version 1.0

RESET

Is Reset a POR

Wait for

VUSB33

Capacitors

discharge

550ms

Crystal

Autodetection

PLL Init

System Init

48msec

System

Ready