ST72F321J ST Microelectronics, ST72F321J Datasheet - Page 104

• Manufacturer Part Number: ST72F321J
• Description: 8-BIT MCU
• Manufacturer: ST Microelectronics

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DataSheet
ST72321J
SERIAL COMMUNICATIONS INTERFACE (Cont’d)
10.6.4.7 Parity Control
Parity control (generation of parity bit in trasmis-
sion and and parity chencking in reception) can be
enabled by setting the PCE bit in the SCICR1 reg-
ister. Depending on the frame length defined by
the M bit, the possible SCI frame formats are as
listed in
Table 21. Frame Formats
Legend: SB = Start Bit, STB = Stop Bit,
PB = Parity Bit
Note: In case of wake up by an address mark, the
MSB bit of the data is taken into account and not
the parity bit
Even parity: the parity bit is calculated to obtain
an even number of “1s” inside the frame made of
the 7 or 8 LSB bits (depending on whether M is
equal to 0 or 1) and the parity bit.
Ex: data=00110101; 4 bits set => parity bit will be
0 if even parity is selected (PS bit = 0).
Odd parity: the parity bit is calculated to obtain an
odd number of “1s” inside the frame made of the 7
or 8 LSB bits (depending on whether M is equal to
0 or 1) and the parity bit.
Ex: data=00110101; 4 bits set => parity bit will be
1 if odd parity is selected (PS bit = 1).
Transmission mode: If the PCE bit is set then the
MSB bit of the data written in the data register is
not transmitted but is changed by the parity bit.
Reception mode: If the PCE bit is set then the in-
terface checks if the received data byte has an
even number of “1s” if even parity is selected
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M bit
4
0
0
1
1
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Table
PCE bit
21.
1
0
0
1
| SB | 7-bit data | PB | STB |
| SB | 8-bit data PB | STB |
| SB | 8 bit data | STB |
| SB | 9-bit data | STB |
SCI frame
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(PS=0) or an odd number of “1s” if odd parity is se-
lected (PS=1). If the parity check fails, the PE flag
is set in the SCISR register and an interrupt is gen-
erated if PIE is set in the SCICR1 register.
10.6.5 Low Power Modes
10.6.6 Interrupts
The SCI interrupt events are connected to the
same interrupt vector.
These events generate an interrupt if the corre-
sponding Enable Control Bit is set and the inter-
rupt mask in the CC register is reset (RIM instruc-
tion).
Mode
WAIT
HALT
Transmit Data Register
Empty
Transmission Com-
plete
Received Data Ready
to be Read
Overrun Error Detected
Idle Line Detected
Parity Error
Interrupt Event
In Halt mode, the SCI stops transmit-
ting/receiving until Halt mode is exit-
ed.
Description
No effect on SCI.
SCI interrupts cause the device to exit
from Wait mode.
SCI registers are frozen.
Event
RDRF
TDRE
Flag
IDLE
OR
TC
PE
Control
Enable
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TCIE
ILIE
Bit
RIE
PIE
TIE
from
Wait
Exit
Yes
Yes
Yes
Yes
Yes
Yes
from
Exit
Halt
No
No
No
No
No
No
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