TM4C1231E6PZ Datasheet, PDF (509/1173 Pages) Texas Instruments – Tiva™ TM4C1231E6PZ Microcontroller

Tiva^™ TM4C1231E6PZ Microcontroller
manufacturing or bring-up mode, care must be taken to ensure all words are written in immediate
succession. If not, then partial password unlock would need to be supported to recover.
■ If the word write requires the block to be written to the copy buffer, then it is possible to fail or
lose power during the subsequent operations. A control word mechanism is used to track what
step the EEPROM was in if a failure occurs. If not completed, the EESUPP register indicates
the partial completion, and the EESUPP START bit can be written to allow it to continue to
completion.
■ If a copy buffer erase fails or power is lost while erasing, the EESUPP register indicates it is not
complete and allows it to be restarted
After a reset and prior to writing any data to the EEPROM, software must read the EESUPP register
and check for the presence of any error condition which may indicate that a write or erase was in
progress when the system was reset due to a voltage drop. If either the PRETRY or ERETRY bits are
set, the peripheral should be reset by setting and then clearing the R0 bit in the EEPROM Software
Reset (SREEPROM) register and waiting for the WORKING bit in the EEDONE register to clear
before again checking the EESUPP register for error indicators. This procedure should allow the
EEPROM to recover from the write or erase error. In very isolated cases, the EESUPP register may
continue to register an error after this operation, in which case the reset should be repeated. After
recovery, the application should rewrite the data which was being programmed when the initial
failure occurred.
Soft Reset Handling
The following soft resets should not be asserted during an EEPROM program or erase operation:
■ Software reset (SYSRESREQ)
■ Software peripheral reset
■ Watchdog reset
■ MOSC failure reset
The WORKING bit of the EEDONE register can be checked before the reset is asserted to see if an
EEPROM program or erase operation is occurring. Soft resets may occur when using a debugger
and should be avoided during an EEPROM operation. A reset such as the Watchdog reset can be
mapped to an external reset using a GPIO, or Hibernate can be entered, if time is not a concern.
Endurance
Endurance is per meta-block which is 2 blocks. Endurance is measured in two ways:
1. To the application, it is the number of writes that can be performed.
2. To the microcontroller, it is the number of erases that can be performed on the meta-block.
Because of the second measure, the number of writes depends on how the writes are performed.
For example:
■ One word can be written more than 500K times, but, these writes impact the meta-block that the
word is within. As a result, writing one word 500K times, then trying to write a nearby word 500K
times is not assured to work. To ensure success, the words should be written more in parallel.
June 12, 2014
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Texas Instruments-Production Data