Capture and store critical information without constant power with 48LM01 and PIC18F57Q43

EERAM 2 Click is based on the 48LM01, a 1024-Kbit SRAM with EEPROM backup in each memory cell from Microchip. The user can treat this device as a full symmetrical read/write SRAM with no limits on cell usage. The device handles backup to EEPROM on any power disruption, so the user can effectively view this device as an SRAM that never loses its data. The SRAM is organized as 131,072 x 8 bits with access via the SPI serial interface. The backup EEPROM is invisible and cannot be accessed by the user independently. The 48LM01 includes circuitry that detects VCC dropping below a certain threshold, shuts its connection to the outside environment, and transfers all SRAM data to the EEPROM portion of each cell for safekeeping. When VCC returns, the circuitry automatically returns the data to the SRAM, and the user’s interaction with the SRAM can continue with the same data set. When power is first

applied to the click board™, the VCAP capacitor is charged to VCC through the 48LM01 IC. During normal SRAM operation, the capacitor remains charged, and the device monitors the level of system VCC. If the system VCC drops below a set threshold, the device interprets this as a power-off or brown-out event. The device suspends all I/O operation, shuts off its connection with the VCC pin, and uses the saved energy in the capacitor to power the device through the VCAP pin as it transfers all SRAM data to EEPROM. On the next power-up of VCC, the data is transferred back to SRAM, the capacitor is recharged, and the SRAM operation continues. Besides standard 4-wire SPI lines, 48LM01 has an additional HOLD pin. This pin can be used for transmission suspension to the 48LM01 while in the middle of a serial sequence without retransmitting the entire sequence. It must be held high any time this function is not

being used. Once the device is selected and a serial sequence is underway, the HOLD pin may be pulled low to pause further serial communication without resetting the serial sequence. The 48LM01 is internally organized as a continuous SRAM array for reading and writing, along with a non-volatile EEPROM array that is not directly accessible to the user but can be refreshed or recalled on power cycles or software commands. The SRAM array is continuously addressable, so the entire array can be written without accessing pages. 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. Also, it comes equipped with a library containing functions and an example code that can be used, as a reference, for further development.

PIC18F57Q43 Curiosity Nano evaluation kit is a cutting-edge hardware platform designed to evaluate microcontrollers within the PIC18-Q43 family. Central to its design is the inclusion of the powerful PIC18F57Q43 microcontroller (MCU), offering advanced functionalities and robust performance. Key features of this evaluation kit include a yellow user LED and a responsive

mechanical user switch, providing seamless interaction and testing. The provision for a 32.768kHz crystal footprint ensures precision timing capabilities. With an onboard debugger boasting a green power and status LED, programming and debugging become intuitive and efficient. Further enhancing its utility is the Virtual serial port (CDC) and a debug GPIO channel (DGI

GPIO), offering extensive connectivity options. Powered via USB, this kit boasts an adjustable target voltage feature facilitated by the MIC5353 LDO regulator, ensuring stable operation with an output voltage ranging from 1.8V to 5.1V, with a maximum output current of 500mA, subject to ambient temperature and voltage constraints.