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Programmable Hardware Manual (PHM)
© Tibbo Technology Inc.
4.1.1.8
Real-time Clock (RTC)
The EM2000 features an onboard real-time clock (RTC). This RTC has a dedicated
backup power input through pin VCCB of the module. Acceptable input voltage range
for the VCCB pin is 1.8~3.3V.
You can connect the VCCB pin directly to the backup battery, just make sure that
the voltage on VCCB line does not exceed 3.3V. You can also forget this line to the
main 3.3V power.
Your Tibbo BASIC/C application can access the RTC through the RTC (rtc.) object,
which is documented in the TIDE, TiOS, Tibbo BASIC, and Tibbo C Manual.
4.1.1.9
Flash and EEPROM Memory
The EM2000 has three kinds of non-volatile memory onboard:
·
1MB program flash.
TiOS occupies 256KB in the program flash memory. The
remaining 768KB can be used to store your compiled application binary and
permanent (unchangeable) data.
·
1MB flash disk
that houses hardened, fault-tolerant file system. The entire disk
can be used by your application to store necessary data. The disk is under the
control of the flash disk (fd.) object.
·
2KB EEPROM.
The EEPROM is almost fully available to your application, save for a
small 28-byte area called the "special configuration area". The EEPROM is
accessed through the storage (stor.) object.
For more information on fd. and stor. objects see TIDE, TiOS, Tibbo BASIC, and
Tibbo C Manual. Details on the special configuration area are provided in the
Platform-dependent Programming Information
section inside the EM2000 platform
documentation (same manual).
On the advice of one of our customers we are giving you the following
reminder: Like all other EEPROMs on the market, EEPROM ICs used in Tibbo
devices allow for a limited number of write cycles. As the Wikipedia article on
EEPROMs (
https://en.wikipedia.org/wiki/EEPROM
) states, the EEPROM "
...has a
limited life for erasing and reprogramming, now reaching a million operations in
modern EEPROMs. In an EEPROM that is frequently reprogrammed while the
computer is in use, the life of the EEPROM is an important design consideration.
"
When planning to use the stor. object, please carefully consider if the planned mode
of EEPROM use will allow the EEPROM to work reliably through the entire projected
life of your product. For more information see
Prolonging and Estimating EEPROM
Like all other flash memory devices on the market, flash ICs used in Tibbo products
only allow for a limited number of write cycles. As the Wikipedia article on flash
memory (
https://en.wikipedia.org/wiki/Flash_memory
) explains, modern flash ICs still
suffer from comparatively low write endurance. In Tibbo devices, this endurance is
around 100'000 write cycles per sector. When you are using the flash memory for
file storage, the fd. object employs sector wear leveling to maximize the life of the
flash IC (but the life still remains limited). If your application employs direct sector
access, then it is your job to plan the application around the life limitations of the
flash memory. For data that changes often, consider using the EEPROM memory
instead. EEPROMs have much better endurance.