NXP Semiconductors FXTH870 D Series, Руководство пользователя

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FXTH870xD
Sensors
Freescale Semiconductor, Inc.
121
13.9 RFM Registers
The RFM contains twelve registers to control its functions and 32 registers to provide access to the output data buffer.
13.9.1 RFM Control Register 0 - RFCR0
The RFCR0 register contains eight control bits for setting the output data rate of the RFM as described in Figure 98 .
The BPS[7:0] bits are set to $34 by an RFMRST signal which results in a default data rate of approximately 9600 bps.
13.10 RFM Control Register 1 - RFCR1
The RFCR1 register contains eight control bits for the RFM as described in Figure 99 .
$0030 Bit 7 6 5 4 3 2 1 Bit 0
R
BPS[7:0]
W
RFMRST:
0 0 1 1 0 1 0 0
Figure 98. RFM Control Register 0 (RFCR0)
Table 73. RFCR0 Field Descriptions
Field Description
7–0
BPS[7:0]
Data Rate - The BPS[7:0] control bits select the data rate for the transmitted datagrams as described by the following equation:
where:
f
DATA
= Data rate in bits/second
f
XTAL
= External crystal frequency in Hz = 26 MHz
BPS= Value of data rate code (BPS[7:0])
Examples of the value for common data rates are given in Table 74 . The BPS[7:0] control bits are set to $34 by the RFMRST
signal which results in a default data rate of 9600 bits/sec.
Table 74. Data Rate Option Examples
Data Rate
BPS[7:0]
Decimal Value
Data Rate
BPS[7:0]
Decimal Value
Target Nominal
f
XTAL
= 26 MHz
Target Nominal
f
XTAL
= 26 MHz
2000 bps 2000.0 249 4800 bps 4807.7 103
2400 bps 2403.8 207 5000 bps 5000.0 99
4000 bps 4000.0 124 9600 bps 9615.4 51
4500 bps 4504.5 110 19200 bps 19230.8 25
$0031 Bit 7 6 5 4 3 2 1 Bit 0
R
FRM[7:0]
W
RFMRST: 0 0 0 0 0 0 0 0
Figure 99. RFM Control Register 1 (RFCR1)
f
DATA
f
XTAL
52 BPS 1 +
  
-------------------------------------
5x10
5
BPS 1 +
 
-------------------------
= =