XE88LC02 Datasheet, PDF (85/184 Pages) List of Unclassifed Manufacturers – Sensing Machine Data Acquisition MCU with 16 + 10 bit ZoomingADC and LCD driver

Datasheet XE88LC02 Sensing
Machine Data Acquisition MCU
with Zooming ADC and LCD driver
14.6 Uart on the RC oscillator or external clock source
To select the external clock or RC oscillator for the Uart, the bit SelXtal in RegUartCmd has to be 0.
The choice between the RC oscillator and the external clock source is made with the bit EnExtClock
in RegSysClock.
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.
Frequency selection for correct Uart baud rates
RC oscillator (Hz)
External clock (Hz)
2’457’600
4’915’200
1’228’800
2’457’600
614’400
1’228’800
307’200
614’400
153’600
307’200
76’800
153’600
Table 14-9a
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 14-9.
RC frequency (Hz)
External clock freq. (Hz)
UartRcSel UartBR
000
111
110
101
100
011
010
001
000
010
001
000
2457600 1228800 614400 307200
4915200 2457600 1228800 614400
153600
76800
38400
19200
9600
4800
2400
1200
600
300
76800
38400
19200
9600
4800
2400
1200
600
300
-
38400
19200
9600
4800
2400
1200
600
300
-
-
19200
9600
4800
2400
1200
600
300
-
-
-
153600
307200
9600
4800
2400
1200
600
300
-
-
-
-
Table 14-9: Uart baud rate with RC clock or external clock
76800
153600
4800
2400
1200
600
300
-
-
-
-
-
Note 1 : Although not documented here, the coding of the baud rate used in the circuits XE88LC01,
XE88LC03 and XE88LC05 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.
14.7 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 14-10.
14-4
D0207-134