ST72321AR9-Auto STMicroelectronics, ST72321AR9-Auto Datasheet - Page 139

• Manufacturer Part Number: ST72321AR9-Auto
• Description: 8-bit MCU for automotive with 60 Kbyte Flash, 10-bit ADC, timers, SPI, SCI and I2C interfaces
• Manufacturer: STMicroelectronics

Specifications of ST72321AR9-Auto

• Hdflash Endurance: 100 cycles, data retention 20 years
• Clock Sources: crystal/ceramic resonator oscillators, internal RC oscillator and bypass for external clock
• 4 Power Saving Modes: Halt, Active Halt, Wait and Slow

ST72321xx-Auto
15.4.2
Note:
Transmitter
The transmitter can send data words of either 8 or 9 bits depending on the M bit status.
When the M bit is set, word length is 9 bits and the 9th bit (the MSB) has to be stored in the
T8 bit in the SCICR1 register.
Character transmission
During an SCI transmission, data shifts out least significant bit first on the TDO pin. In this
mode, the SCIDR register consists of a buffer (TDR) between the internal bus and the
transmit shift register (see
Procedure
1.
2.
3.
4.
Clearing the TDRE bit is always performed by the following software sequence:
1.
2.
The TDRE bit is set by hardware and it indicates:
●
●
●
This flag generates an interrupt if the TIE bit is set and the I bit is cleared in the CCR
register.
When a transmission is taking place, a write instruction to the SCIDR register stores the
data in the TDR register and which is copied in the shift register at the end of the current
transmission.
When no transmission is taking place, a write instruction to the SCIDR register places the
data directly in the shift register, the data transmission starts, and the TDRE bit is
immediately set.
When a frame transmission is complete (after the stop bit) the TC bit is set and an interrupt
is generated if the TCIE is set and the I bit is cleared in the CCR register.
Clearing the TC bit is performed by the following software sequence:
1.
2.
The TDRE and TC bits are cleared by the same software sequence.
Break characters
Setting the SBK bit loads the shift register with a break character. The break frame length
depends on the M bit (see
As long as the SBK bit is set, the SCI send break frames to the TDO pin. After clearing this
Select the M bit to define the word length.
Select the desired baud rate using the SCIBRR and the SCIETPR registers.
Set the TE bit to assign the TDO pin to the alternate function and to send an idle frame
as first transmission.
Access the SCISR register and write the data to send in the SCIDR register (this
sequence clears the TDRE bit). Repeat this sequence for each data to be transmitted.
An access to the SCISR register
A write to the SCIDR register
The TDR register is empty.
The data transfer is beginning.
The next data can be written in the SCIDR register without overwriting the previous
data.
An access to the SCISR register
A write to the SCIDR register
Figure
Figure
Doc ID 13829 Rev 1
62).
63).
Serial communications interface (SCI)
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