CHAPTER 17 FLASH MEMORY

17.7Notes on using Flash Memory

This section provides notes on using the MB89F202, especially for flash memory.

■Input of a Hardware Reset (RST)

To input a hardware reset when reading is in progress, i.e., when the automatic algorithm has not been started, secure a minimum low-level width of 1650 ns.

To input a hardware reset while a write or erase is in progress, i.e., while the automatic algorithm is being started, secure a minimum low-level width of 1650 ns. In this case, 20 ∝s are required until the data becomes readable after the operation being performed terminates and the flash memory is fully initialized.

Performing a hardware reset during a write operation makes the data being written undetermined. Also note that performing a hardware reset or shut-down during an erase operation may make the sector from which data is being erased unusable.

■Software Reset, Watchdog Timer Reset

When write/erase of flash memory is set up for normal mode and CPU memory access mode is internal ROM mode, and if a reset cause occurs while the automatic algorithm of flash memory is being activated, the CPU may run out of control.

The cause of a reset does not initialize the flash memory and keeps the automatic algorithm operating. Thus, when the CPU starts a sequence after the reset is cancelled, the flash memory may not have been in a read state. Prevent a cause of a reset from occurring while the flash memory is writing or erasing.

■Program Access to Flash Memory

While the automatic algorithm is being activated, any read access to the flash memory is disabled. When CPU memory access mode is set to internal ROM mode, move program areas into another area such as RAM, and then start a write or erase.

In this case, when the flash containing interrupt vectors are erased, the writing or erasing of interrupt processing cannot be executed.

For the same reason, other interrupt processing shall be disabled while the automatic algorithm is being activated.

■Flash Content Protection

Flash content can be read using parallel / serial programmer if the flash content protection mechanism is not activated.

One predefined area of the flash (FFFCH) is assigned to be used for preventing the read access of flash content. If the protection code "01H" is written in this address (FFFCH), the flash content cannot be read by any parallel / serial programmer.

Note : The program written into the flash cannot be verified once the flash protection code is written ("01H" in FFFCH). It is advised to write the flash protection code at last.

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Fujitsu F202RA, MB89202 Software Reset, Watchdog Timer Reset, Program Access to Flash Memory, Flash Content Protection
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F202RA, MB89202 specifications

The Fujitsu MB89202 and F202RA microcontrollers are part of the 16-bit microcontroller family, renowned for their robust performance and versatility in a variety of embedded system applications. These devices are tailored for high-efficiency operation across diverse industries, including automotive, consumer electronics, and industrial automation.

One of the main features of the MB89202 is its powerful CPU core, which operates at a clock speed of up to 20 MHz. This enables the microcontroller to perform complex calculations and consumer-grade applications seamlessly. The architecture is designed to handle multiple tasks effectively, making it suitable for real-time operations.

Memory capacity is a vital characteristic of the MB89202, featuring on-chip RAM and ROM configurations. The microcontroller can accommodate different memory variants, providing developers with flexibility in memory allocation based on their application requirements. This adaptability facilitates applications ranging from simple control systems to complex data processing tasks.

The F202RA variant extends the capabilities of the MB89202 by integrating advanced peripheral functions. It includes built-in timers, A/D converters, and serial communication interfaces, which are essential for interfacing with other hardware components or sensors. The availability of these peripherals reduces the need for additional external circuits, thus contributing to a more compact and cost-effective design.

In terms of power management, the MB89202 series employs advanced power-saving technologies. The microcontroller offers various low-power modes, enabling devices to conserve energy during idle times, making it highly suitable for battery-operated applications. This characteristic not only enhances the efficiency of devices but also extends their operational lifespan.

Moreover, the Fujitsu MB89202 series incorporates robust protection features, including watchdog timers and failure detection mechanisms. These safety features ensure reliable operation in critical systems, making them a preferred choice in applications where failure is not an option.

The MB89202 and F202RA microcontrollers also support a range of development tools and environments, including integrated development environments (IDEs) and software libraries, which facilitate rapid application development. With these tools, developers can efficiently prototype, debug, and optimize their applications.

In summary, the Fujitsu MB89202 and F202RA microcontrollers stand out with their efficient performance, extensive memory options, integrated peripherals, and power-saving capabilities, making them ideal for a wide array of embedded applications. Their reliability and robustness further enhance their attractiveness for designers seeking advanced microcontroller solutions.
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