XE8000EV108 Semtech, XE8000EV108 Datasheet - Page 111

• Manufacturer Part Number: XE8000EV108
• Description: EVAL BOARD FOR XE8806/XE8807
• Manufacturer: Semtech
• Type: MCUr

Specifications of XE8000EV108

• Contents: Fully Assembled Evaluation Board
• For Use With/related Products: XE88LC06AMI026
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

In order to obtain a correct baud rate, the RC oscillator or external clock frequency have to be set to one of the
frequencies given in the table below. The precision of the obtained baud rate is directly proportional to the
frequency deviation of the used clock source with respect to the values in the table below.
For each of these frequencies, the baud rate can be selected with the bits UartBR(2:0) in RegUartCtrl and
UartRcSel(2:0) in RegUartCmd as shown in Table 15-9.
RC frequency (Hz)
External clock freq. (Hz)
Note 1 : Although not documented here, the coding of the baud rate used in the circuits XE8801, XE8803 and
XE8805 can also be used.
Note 2 : The precision of the baud rate is directly proportional to the frequency deviation of the used clock from the
ideal frequency given in the table. In order to increase the precision and stability of the RC oscillator, the DFLL
(digital frequency locked loop) can be used with the crystal oscillator as a reference.
15.7 UART on the crystal oscillator
In order to use the crystal oscillator as the clock source for the UART, the bit SelXtal in RegUartCmd has to be
set. The crystal oscillator has to be enabled by setting the EnableXtal bit in RegSysClock. The baud rate selection
is done using the UartBR bits as shown in Table 15-10.
© Semtech 2006
UartRcSel
000
010
UartBR
111
110
101
100
011
010
001
000
001
000
RC oscillator (Hz)
2’457’600
1’228’800
614’400
307’200
153’600
76’800
Frequency selection for correct Uart baud rates
2457600
4915200
153600
76800
38400
19200
9600
4800
2400
1200
600
300
Table 15-9: Uart baud rate with RC clock or external clock
Table 15-10: UART baud rate with Xtal clock
1228800
2457600
Xtal freq. (Hz)
76800
38400
19200
9600
4800
2400
1200
600
300
-
UartBR
011
010
001
000
Table 15-9a
1228800
614400
38400
19200
9600
4800
2400
1200
15-4
600
300
-
-
32768
2400
1200
External clock (Hz)
600
300
307200
614400
19200
9600
4800
2400
1200
600
300
-
-
-
4’915’200
2’457’600
1’228’800
614’400
307’200
153’600
153600
307200
9600
4800
2400
1200
600
300
-
-
-
-
XE8806A/XE8807A
153600
76800
4800
2400
1200
600
300
-
-
-
-
-
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