sx1441 Semtech Corporation, sx1441 Datasheet - Page 52

• Manufacturer Part Number: sx1441
• Description: Bluetooth V1.2 Soc For Voice And Data Applications With Dsp Capabilities
• Manufacturer: Semtech Corporation

Personal Area Network
3.12.4 Configuration
The configuration bits of the UART can be found in the registers RegUartFifoBaud, RegUartFifoCtrl and
RegUartFifoMisc.
The bits UartEnRx and UartEnTx are used to enable or disable the reception and transmission. The word length
(7 or 8 data bits) can be chosen with UartWL. A parity bit is added during transmission or checked during reception
if UartPE is set. The parity mode (odd or even) can be chosen with UartPM. Setting the bits UartXRx and UartXTx
respectively inverts the UA_RX and UA_TX signals.
The bit UartEcho automatically sends back the received data. The transmission function becomes then UA_TX =
UA_RX XOR UartXRx XOR UartXTx. UartEnRx or UartEnTx must be set to 1 to use the echo mode.
The bits UartFlowCtrl, RtsLevelMode and RtsMonitorMode are used to control the flow through RTS and CTS
pins as described in paragraph 3.12.8.
3.12.5 Baud Rates
The UART interface can be clocked by ckRCext when the Sel32k bit is cleared. UartRcSel and UartRcDiv select
the baud rate. The relation between the baudrate and the ckRCext clock frequency is given by:
FactorUartRcSel is the prescaler tap selection set by the bits UartRcSel in RegUartFifoBaud and factorUartRcDiv
is the division set by the bits UartRcDiv in RegUartFifoBaud. The values of these factors are given in the Table
91 and Table 92. With a 14 MHz frequency clock, the highest baudrate is 875 kbits/s.
Due to the RC clock dispersion, a digital frequency lock loop (DFLL) must be used to calibrate it before using it as
a clock source.
© Semtech 2006
UartRcDiv
UartRcSel
Baudrate
00000
00001
00010
00011
00100
00101
00110
00111
01000
01001
01010
01011
01100
01101
01110
000
001
010
011
100
101
110
111
Table 91 - Division factor for UartRcSel
=
Equation 3 – Baudrate vs. ckRCext
16
⋅
factorUart
52
factorUartRcSel
RcSel
factorUartRcDiv
f
ckRCext
⋅
factorUart
RcDiv
128
16
32
64
10
11
12
13
14
15
1
2
4
8
1
2
3
4
5
6
7
8
9
SX1441 – Bluetooth® 1.2 SoC
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Data Sheet