LG KE820 Service Manual page 56

3. TECHNICAL BRIEF
3.17.6 System Integration
Figure 30 Mobile system integration
The UART (serial interface) is used for the software interface between S-Gold2 baseband and the
Bluetooth chip. For the HCI UART transport layer four interface lines are needed, two for data
(UARTTXD and UARTRXD) and two for hardware flow control (UARTRTS and UARTCTS). For the
HCI Three-Wire UART transport layer two interface lines (UARTTXD and UARTRXD) are needed. The
hardware flow control lines (UARTRTS and UARTCTS) are supported but the use is optional. In
KE820/KG99 used three-wire UART communication.
The UART interface has its own supply voltage (VDDUART) to ensure compatibility with the I/O
voltages used by the S-Gold2.
The PCM/I2S interface is used as audio interface and can handle up to two voice channels. The PCM
interface also has its own supply voltage (VDDPCM) to ensure compatibility with the I/O voltages used
by the S-Gold2 baseband processor.
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