131
MC95FG308 / MC95FG208
ABOV Semiconductor Co., Ltd.
The Frame Error (FE) flag indicates the state of the first stop bit. The FE flag is zero when the stop bit was correctly
detected as one, and the FE flag is one when the stop bit was incorrect, ie detected as zero. This flag can be used for
detecting out-of-sync conditions between data frames.
The Data OverRun (DOR) flag indicates data loss due to a receive buffer full condition. A DOR occurs when the
receive buffer is full, and another new data is present in the receive shift register which are to be stored into the receive
buffer. After the DOR flag is set, all the incoming data are lost. To prevent data loss or clear this flag, read the receive
buffer.
The Parity Error (PE) flag indicates that the frame in the receive buffer had a Parity Error when received. If Parity
Check function is not enabled (UPM[1]=0), the PE bit is always read zero.
Note) The error flags related to receive operation are not used when USART is in SPI mode.
11.7.9.3
Parity Checker
If Parity bit is enabled (UPM[1]=1), the Parity Checker calculates the parity of the data bits in incoming frame and
compares the result with the parity bit from the received serial frame.
11.7.9.4
Disabling Receiver
In contrast to Transmitter, disabling the Receiver by clearing RXE bit makes the Receiver inactive immediately. When
the Receiver is disabled the Receiver flushes the receive buffer and the remaining data in the buffer is all reset. The
RXD pin is not overridden the function of USART, so RXD pin becomes normal GPIO or primary function pin.
11.7.9.5
Asynchronous Data Reception
To receive asynchronous data frame, the USART includes a clock and data recovery unit. The Clock Recovery logic is
used for synchronizing the internally generated baud-rate clock to the incoming asynchronous serial frame on the RXD
pin.
The Data recovery logic samples and low pass filters the incoming bits, and this removes the noise of RXD pin.
The next figure illustrates the sampling process of the start bit of an incoming frame. The sampling rate is 16 times the
baud-rate for normal mode, and 8 times the baud rate for Double Speed mode (U2X=1). The horizontal arrows show
the synchronization variation due to the asynchronous sampling process. Note that larger time variation is shown
when using the Double Speed mode.
Figure 11.43
Start bit Sampling
RxD
0
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14 15
16
1
2
3
IDLE
BIT0
START
0
1
2
3
4
5
6
7
8
1
2
Sample
(U2X = 0)
Sample
(U2X = 1)
Содержание MC95FG208 Series
Страница 14: ...14 MC95FG308 MC95FG208 ABOV Semiconductor Co Ltd 4 Package Diagram Figure 4 1 32 Pin SOP Package...
Страница 15: ...15 MC95FG308 MC95FG208 ABOV Semiconductor Co Ltd Figure 4 2 32 Pin QFN Package...
Страница 16: ...16 MC95FG308 MC95FG208 ABOV Semiconductor Co Ltd Figure 4 3 32 Pin LQFP Package...
Страница 17: ...17 MC95FG308 MC95FG208 ABOV Semiconductor Co Ltd Figure 4 4 28 Pin SOP Package...
Страница 18: ...18 MC95FG308 MC95FG208 ABOV Semiconductor Co Ltd Figure 4 5 28 Pin SOP Package continue...
Страница 19: ...19 MC95FG308 MC95FG208 ABOV Semiconductor Co Ltd Figure 4 6 28 Pin SOP Package...
Страница 20: ...20 MC95FG308 MC95FG208 ABOV Semiconductor Co Ltd Figure 4 7 28 Pin TSSOP Package...
Страница 21: ...21 MC95FG308 MC95FG208 ABOV Semiconductor Co Ltd Figure 4 8 20 Pin SOP Package...
Страница 22: ...22 MC95FG308 MC95FG208 ABOV Semiconductor Co Ltd Figure 4 9 20 Pin TSSOP Package...
Страница 23: ...23 MC95FG308 MC95FG208 ABOV Semiconductor Co Ltd Figure 4 10 16 Pin SOP Package...
Страница 24: ...24 MC95FG308 MC95FG208 ABOV Semiconductor Co Ltd Figure 4 11 16 Pin TSSOP Package...