![](http://datasheet.mmic.net.cn/30000/MQ83C154DXXX-25-883R_datasheet_2377229/MQ83C154DXXX-25-883R_807.png)
807
6384E–ATARM–05-Feb-10
AT91SAM9G20
None.
44.2.7.3
SSC: Transmitter Limitations in Slave Mode
If TK is programmed as output and TF is programmed as input, it is impossible to emit data
when start of edge (rising or falling) of synchro with a Start Delay equal to zero.
Problem Fix/Workaround
None.
44.2.7.4
SSC: Periodic Transmission Limitations in Master Mode
If Last Significant Bit is sent first (MSBF = 0) the first TAG during the frame synchro is not sent.
Problem Fix/Workaround
None.
44.2.8
Shutdown Controller (SHDWC)
44.2.8.1
SHDWC: SHDN Signal may be Driven to Low Level Voltage During Device Power-on
If only VDDBU is powered during boot sequence (No VDDCORE), the SHDN signal may be
driven to low level voltage after a delay.This delay is linked to the startup time of the slow clock
selected by OSCSEL signal.
If SHDN pin is connected to the Enable pin (EN) of the VDDCORE regulator, VDDCORE estab-
lishment does not occur and the system does not start.
Problem Fix/Workaround
1.
VDDCORE must be established within the delay corresponding to the startup time of
the slow clock selected by OSCSEL.
2.
Add a glue logic to latch the rising edge of the SHDN signal. The reset of the latch out-
put (EN_REG) can be connected to a PIO and used to enter the shutdown mode.
44.2.9
Static Memory Controller (SMC)
44.2.9.1
SMC: Chip Select Parameters Modification
The user must not change the configuration parameters of an SMC Chip Select (Setup, Pulse,
Cycle, Mode) if accesses are performed on this CS during the modification.
For example, the modification of the Chip Select 0 (CS0) parameters, while fetching the code
from a memory connected on this CS0, may lead to unpredictable behavior.
Problem Fix/Workaround
The code used to modify the parameters of an SMC Chip Select can be executed from the inter-
nal RAM or from a memory connected to another Chip Select
44.2.10
System Controller (SYSC)
44.2.10.1
SYSC: Possible Event Loss when reading RTT_SR
If an event (RTTINC or ALMS) occurs within the same slow clock cycle as when the RTT_SR is
read, the corresponding bit might be cleared. This can lead to the loss of this event.
Problem Fix/Workaround
The software must handle an RTT event as an interrupt and should not poll RTT_SR.