mc68hc11f1cpu3 Freescale Semiconductor, Inc, mc68hc11f1cpu3 Datasheet - Page 96

• Manufacturer Part Number: mc68hc11f1cpu3
• Description: Mc68hc11f1 Microcontroller
• Manufacturer: Freescale Semiconductor, Inc

7.7 Status Flags and Interrupts
7-10
The SCI transmitter has two status flags. These status flags can be read by software
(polled) to tell when the corresponding condition exists. Alternatively, a local interrupt
enable bit can be set to enable each of these status conditions to generate interrupt
requests when the corresponding condition is present. Status flags are automatically
set by hardware logic conditions, but must be cleared by software, which provides an
interlock mechanism that enables logic to know when software has noticed the status
indication. The software clearing sequence for these flags is automatic — functions
that are normally performed in response to the status flags also satisfy the conditions
of the clearing sequence.
EXTAL
XTAL
Figure 7-3 SCI Baud Rate Generator Block Diagram
CLOCK GENERATOR
OSCILLATOR
AND
( 4)
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AS
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2
2
2
2
2
2
2
0:0
SCR2:SCR1:SCR0
0:0:0
0:0:1
0:1:0
0:1:1
1:0:0
1:0:1
1:1:0
1:1:1
3
0:1
4
1:0
BAUD RATE
BAUD RATE
TRANSMIT
RECEIVE
(16X)
(1X)
SCI
SCI
13
16
SCP1:SCP0
1:1
TECHNICAL DATA
MC68HC11F1
INTERNAL
BUS
CLOCK
(PH2)