ST72321AR9-Auto STMicroelectronics, ST72321AR9-Auto Datasheet - Page 239

• 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
22.1.7
22.1.8
SCI wrong break duration
Description
A single break character is sent by setting and resetting the SBK bit in the SCICR2 register.
In some cases, the break character may have a longer duration than expected:
●
●
In the same way, as long as the SBK bit is set, break characters are sent to the TDO pin.
This may lead to generating one break more than expected.
Occurrence
The occurrence of the problem is random and proportional to the baud rate. With a transmit
frequency of 19200 baud (f
occurrence is around 1%.
Workaround
If this wrong duration is not compliant with the communication protocol in the application,
software can request that an Idle line be generated before the break character. In this case,
the break duration is always correct assuming the application is not doing anything between
the idle and the break. This can be ensured by temporarily disabling interrupts.
The exact sequence is:
●
●
●
●
16-bit timer PWM mode
In PWM mode, the first PWM pulse is missed after writing the value FFFCh in the OC1R
register (OC1HR, OC1LR). It leads to either full or no PWM during a period, depending on
the OLVL1 and OLVL2 settings.
20 bits instead of 10 bits if M = 0
22 bits instead of 11 bits if M = 1
Disable interrupts
Reset and Set TE (IDLE request)
Set and Reset SBK (Break Request)
Re-enable interrupts
CPU
Doc ID 13829 Rev 1
= 8 MHz and SCIBRR = 0xC9), the wrong break duration
Known limitations
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