ReRAM 2 Click is a compact add-on board containing highly reliable resistive random-access memory. This board features the MB85AS8MT, an 8Mbit memory organized as 1,048,576 words of 8 bits from Fujitsu Semiconductor. The MB85AS8MT uses the resistance-variable memory process and silicon-gate CMOS process technologies to form nonvolatile memory cells. This SPI configurable ReRAM can withstand many write cycles (1x106 rewrite operations), has a data retention period greater than ten years, and can read and write to random addresses with very negligible delay. This Click board™ is ideal as a nonvolatile storage media or temporary RAM expansion for storing variables in any embedded application that requires rapid writes and unlimited endurance.

ReRAM 2 Click is supported by a mikroSDK compliant library, which includes functions that simplify software development.

ReRAM 2 Click as its foundation uses the MB85AS8MT, a highly reliable 8Mbit resistive random-access memory (ReRAM) organized as 1,048,576 words of 8 bits from Fujitsu Semiconductor. It uses the resistance-variable memory process and silicon-gate CMOS process technologies to form nonvolatile memory cells. The MB85AS8MT specifies 1.000.000 endurance cycles with data retention of a minimum of 10 years, which gives the MB85AS8MT the capability to handle unlimited reads/writes to the memory.

One prominent feature of the MB85AS8MT is an extremely small average current, despite its large density, for reading operations of 0.15mA at an operating frequency of 5MHz, which is only 5% of large density EEPROM devices. This feature enables minimal power consumption when in applications with frequent data-read operations. Besides higher write endurance, it has faster write speeds than EEPROM and flash memory, while its electric specifications, such as commands and timings, are compatible with EEPROM products.

The ReRAM 2 Click communicates with MCU through a standard SPI interface that enables high clock speeds up to 10MHz, supporting the two most common SPI modes, SPI Mode 0 and 3. An additional feature of this Click board™ represents the configurable Write Protection function labeled as WP routed on the PWM pin of the mikroBUS™ socket. The WP pin protects the entire memory and all registers from write operations and must be set to a low logic state to inhibit all the write operations. All memory and register writes are prohibited when this pin is low, and the address counter is not incremented. Besides, the ReRAM 2 Click also has an additional HOLD pin, routed to the RST pin of the mikroBUS™ socket labeled as HO, to interrupt a serial operation without aborting it.

This Click board™ can be operated only with a 3.3V logic voltage level. The board must perform appropriate logic voltage level conversion before using MCUs with different logic levels. However, the Click board™ comes equipped with a library containing functions and an example code that can be used, as a reference, for further development.

• Interface: SPI
• Compatibility: mikroBUS™
• Dimensions: 28.6 x 25.4mm
• Input Voltage: 3.3V
• Memory Size: 8 Mbit
• Write Endurance: 10⁶ Write Cycles
• Data Retention: 10 Years
• Operating Temperature Range: Min. -40°C, Typ. +25°C, Max. +85°C

• Schematic
• B85AS8MT Datasheet
• mikroSDK
• GitHub