Serial Interfaces; Primary Uart (Uart1); Secondary Uart (Uart2); Uart1 Interface Signals - Motorola 8900 - Blackberry Curve Cell Phone OEM Car Charger Developer's Manual

Chapter 2: Hardware Interface Description

Serial Interfaces

C24 includes three completely independent serial communications interfaces, which may be used
by the application for several purposes.

Primary UART (UART1)

The C24 primary UART is a standard 8-signal port for RS232. The UART is used for all the
communications with C24 - AT commands interface, 1x data and CSD data, programming and
software upgrades.
The UART signals are active low CMOS level signals. For standard RS232 communications with
a PC, an external transceiver is required.
C24 is defined as a DCE device, and the user application is defined as the DTE device. These
definitions apply for the UART signals naming conventions, and the direction of data flow, as
described in Figure 2-10.
Figure 2-10: UART1 Interface Signals
The C24 primary UART supports baud rates 300, 600, 1200, 2400, 4800, 9600, 19200, 38400,
57600, 115200 and 230400 bps.
Auto baud rate detection is not supported and the default baud rate is 115200 bps.
All flow control handshakes are supported: hardware, software, or none.
The UART default port configuration is 8 data bits, 1 stop bit and no parity, with hardware flow
control and 115200 baud rate.

Secondary UART (UART2)

The secondary UART is a 4-signal interface, which only provides data and flow control signals.
The secondary UART is used to communicate GPS data in NMEA format.
The UART signals are active low CMOS level signals. For standard RS232 communications with
a PC, an external transceiver is required.
December 15, 2008 C24 Module Hardware Description 21