st7fmc2s7t6 STMicroelectronics, st7fmc2s7t6 Datasheet - Page 300

• Manufacturer Part Number: st7fmc2s7t6
• Description: 8-bit Mcu With Nested Interrupts, Flash, 10-bit Adc, Brushless Motor Control, Five Timers, Spi, Linsci
• Manufacturer: STMicroelectronics

ST7MC1/ST7MC2
IMPORTANT NOTES (Cont’d)
15.2 CLEARING ACTIVE INTERRUPTS OUTSIDE
INTERRUPT ROUTINE
When an active interrupt request occurs at the
same time as the related flag or interrupt mask is
being cleared, the CC register may be corrupted.
Concurrent interrupt context
The symptom does not occur when the interrupts
are handled normally, i.e. when:
- The interrupt request is cleared (flag reset or in-
terrupt mask) within its own interrupt routine
- The interrupt request is cleared (flag reset or in-
terrupt mask) within any interrupt routine
- The interrupt request is cleared (flag reset or in-
terrupt mask) in any part of the code while this in-
terrupt is disabled
If these conditions are not met, the symptom can
be avoided by implementing the following se-
quence:
Perform SIM and RIM operation before and after
resetting an active interrupt request
Nested interrupt context
The symptom does not occur when the interrupts
are handled normally, i.e. when:
- The interrupt request is cleared (flag reset or in-
terrupt mask) within its own interrupt routine
- The interrupt request is cleared (flag reset or in-
terrupt mask) within any interrupt routine with high-
er or identical priority level
- The interrupt request is cleared (flag reset or in-
terrupt mask) in any part of the code while this in-
terrupt is disabled
300/308
Ex:
SIM
reset flag or interrupt mask
RIM
If these conditions are not met, the symptom can
be avoided by implementing the following se-
quence:
15.3 LINSCI LIMITATIONS
15.3.1 LINSCI wrong break duration
SCI Mode
A single break character is sent by setting and re-
setting the SBK bit in the SCICR2 register. In
some cases, the break character may have a long-
er duration than expected:
- 20 bits instead of 10 bits if M=0
- 22 bits instead of 11 bits if M=1.
In the same way, as long as the SBK bit is set,
break characters are sent to the TDO pin. This
may lead to generate one break more than expect-
ed.
Occurrence
The occurrence of the problem is random and pro-
portional to the baudrate. With a transmit frequen-
cy of 19200 baud (fCPU=8MHz and SCI-
BRR=0xC9), the wrong break duration occurrence
is around 1%.
Workaround
If this wrong duration is not compliant with the
communication protocol in the application, soft-
ware can request that an Idle line be generated
before the break character. In this case, the break
duration is always correct assuming the applica-
tion is not doing anything between the idle and the
PUSH CC
SIM
reset flag or interrupt mask
POP CC