ST72C334N2T6 STMicroelectronics, ST72C334N2T6 Datasheet - Page 91

• Manufacturer Part Number: ST72C334N2T6
• Description: Microcontrollers (MCU) Flash 8K SPI/SCI
• Manufacturer: STMicroelectronics

Specifications of ST72C334N2T6

• Data Bus Width: 8 bit
• Program Memory Type: Flash
• Program Memory Size: 8 KB
• Data Ram Size: 384 B
• Interface Type: SCI, SPI
• Maximum Clock Frequency: 8 MHz
• Number Of Programmable I/os: 32
• Number Of Timers: 16 bit
• Operating Supply Voltage: 3.2 V to 5.5 V
• Maximum Operating Temperature: + 85 C
• Mounting Style: SMD/SMT
• Package / Case: TQFP-64
• Minimum Operating Temperature: - 40 C
• On-chip Adc: 8 bit
• Lead Free Status / Rohs Status: In Transition

SERIAL COMMUNICATIONS INTERFACE (Cont’d)
6.6.7 Register Description
STATUS REGISTER (SR)
Read Only
Reset Value: 1100 0000 (C0h)
Bit 7 = TDRE Transmit data register empty.
This bit is set by hardware when the content of the
TDR register has been transferred into the shift
register. An interrupt is generated if the TIE =1 in
the CR2 register. It is cleared by a software se-
quence (an access to the SR register followed by a
write to the DR register).
0: Data is not transferred to the shift register
1: Data is transferred to the shift register
Note: data will not be transferred to the shift regis-
ter as long as the TDRE bit is not reset.
Bit 6 = TC Transmission complete.
This bit is set by hardware when transmission of a
frame containing Data, a Preamble or a Break is
complete. An interrupt is generated if TCIE=1 in
the CR2 register. It is cleared by a software se-
quence (an access to the SR register followed by a
write to the DR register).
0: Transmission is not complete
1: Transmission is complete
Bit 5 = RDRF Received data ready flag.
This bit is set by hardware when the content of the
RDR register has been transferred into the DR
register. An interrupt is generated if RIE=1 in the
CR2 register. It is cleared by hardware when
RE=0 or by a software sequence (an access to the
SR register followed by a read to the DR register).
0: Data is not received
1: Received data is ready to be read
Bit 4 = IDLE Idle line detect.
This bit is set by hardware when a Idle Line is de-
tected. An interrupt is generated if the ILIE=1 in
the CR2 register. It is cleared by hardware when
RE=0 by a software sequence (an access to the
SR register followed by a read to the DR register).
0: No Idle Line is detected
1: Idle Line is detected
TDRE
7
TC
RDRF
IDLE
OR
NF
FE
0
-
Note: The IDLE bit will not be set again until the
RDRF bit has been set itself (i.e. a new idle line oc-
curs). This bit is not set by an idle line when the re-
ceiver wakes up from wake-up mode.
Bit 3 = OR Overrun error.
This bit is set by hardware when the word currently
being received in the shift register is ready to be
transferred into the RDR register while RDRF=1.
An interrupt is generated if RIE=1 in the CR2 reg-
ister. It is cleared by hardware when RE=0 by a
software sequence (an access to the SR register
followed by a read to the DR register).
0: No Overrun error
1: Overrun error is detected
Note: When this bit is set RDR register content will
not be lost but the shift register will be overwritten.
Bit 2 = NF Noise flag.
This bit is set by hardware when noise is detected
on a received frame. It is cleared by hardware
when RE=0 by a software sequence (an access to
the SR register followed by a read to the DR regis-
ter).
0: No noise is detected
1: Noise is detected
Note: This bit does not generate interrupt as it ap-
pears at the same time as the RDRF bit which it-
self generates an interrupt.
Bit 1 = FE Framing error.
This bit is set by hardware when a de-synchroniza-
tion, excessive noise or a break character is de-
tected. It is cleared by hardware when RE=0 by a
software sequence (an access to the SR register
followed by a read to the DR register).
0: No Framing error is detected
1: Framing error or break character is detected
Note: This bit does not generate interrupt as it ap-
pears at the same time as the RDRF bit which it-
self generates an interrupt. If the word currently
being transferred causes both frame error and
overrun error, it will be transferred and only the OR
bit will be set.
Bit 0 = Unused.
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