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TC1784
Program Memory Unit (PMU)
User´s Manual
5-93
V1.1, 2011-05
PMU, V1.47
a) If the marker is erased the data part could have been programmed incompletely.
Therefore the data part should not be used or alternatively it could be programmed
again to a following page.
b) If the marker contains incorrect data the data part was most likely programmed
correctly but the marker was programmed incompletely. The page could be used
as is or alternatively the data could be programmed again to a following page.
c) If the marker is ok the data part was programmed completely and has the full
retention. However this is not ensured for the marker part itself. Therefore the
algorithm must be robust against the case that the marker becomes unreadable
later.
Recovery From Aborted Logical Sector Erase (“ALSE”)
When while erasing one of the logical sectors a power failure occurs or a reset is
triggered the aborted erase process might leave the complete physical sector
unreadable. As often the logical sectors contain important boot code the application
might not start anymore. Thus the recommended step to repeat the aborted erase after
startup can not be realized.
The FAM implements two recovery algorithms. The selection between the two is done
with the SPREC bit (“Soft-Programming Recovery”), i.e. bit 0 of byte 2 in the UCB1 (see
“User Configuration Block UCB1” on Page 5-76
In both cases the algorithm checks first the sectors PS0 and PS4 for an over-erased
state. When this is detected the bit FSR.VER is set to inform the application (see
). After that the algorithm tries to repair this state:
•
The default algorithm is selected with SPREC = 0. The over-erased logical sector is
searched. When finding one this algorithm programs it shortly with all-one data. The
other logical sectors become readable again.
At least theoretically (especially when operating the device outside of the allowed
operating conditions) this algorithm could destroy valid data: when an over-erased
logical sector is reported incorrectly during normal startup without a preceding sector
erase the data of a logical sector would be overwritten with all-one.
•
An alternative algorithm is selected when SPREC = 1. This algorithm searches also
for the over-erased logical sector as before. For repair a smarter but more time
consuming algorithm is performed. The affected logical sector is not overwritten with
all-one but only the over-erased 0-bits are slightly programmed so that they become
normal 0-bits again. Under all circumstances this algorithm can not destroy any data
but when a lot of data has to be repaired the flash startup time can be increased to
over 250 ms.
Note: The ALSE recovery algorithm is triggered by every reset. However in case of an
application reset at high clock frequencies the algorithm “SPREC=1” might not
finish before the watchdog is triggered. This can cause a device hang-up. A
Summary of Contents for TC1784
Page 1: ...User s Manual V1 1 2011 05 Microcontrollers TC1784 32 Bit Single Chip Microcontroller ...
Page 3: ...User s Manual V1 1 2011 05 Microcontrollers TC1784 32 Bit Single Chip Microcontroller ...
Page 950: ...TC1784 Direct Memory Access Controller DMA User s Manual 11 132 V1 1 2011 05 DMA V3 03 ...
Page 1949: ...TC1784 General Purpose Timer Array GPTA v5 User s Manual 21 297 V1 1 2011 05 GPTA v5 V1 14 ...
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