Secondary Uart (Uart2); Usb Interface - Motorola G24 Developer's Manual

Chapter 2: Hardware Interface Description

Secondary UART (UART2)

The secondary UART is a 4-signal interface, which only provides data and flow control signals.
The secondary UART is designed, but not limited, to enhance the G24 capabilities by providing
connectivity to external devices or applications that require serial communications, such as GPS
receivers or Bluetooth wireless devices.
The secondary UART may also be used for standard serial communications, like the primary
UART.
The UART signals are active low CMOS level signals. For standard RS232 communications with
a PC, an external transceiver is required.
G24 is defined as a DCE device, and the user application is defined as the DCE device. These
definitions apply for the UART signals naming conventions, and the direction of data flow, as
described in Figure 2-13.
Figure 2-13: UART2 Interface Signals

USB Interface

G24 incorporates a standard Universal Serial Bus (USB) interface.
The G24 USB electrical interface and protocol conform to the USB 2.0 full-speed specifications.
G24 is defined as a USB device on the USB bus and does not support hub or host functionality.
USB may be used for standard communications with G24, as done through the UART interface.
When USB is active, G24's low power mode cannot be operated.
Important:
The USB interface signals are shown in Figure 2-14.
Figure 2-14: USB Interface Signals
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