How to Use 25LC160: Examples, Pinouts, and Specs

The 25LC160 is a 16K-bit (2K x 8) serial EEPROM manufactured by Microchip Technology. It is designed for non-volatile data storage, meaning it retains data even when power is removed. The device communicates using the Serial Peripheral Interface (SPI) protocol, making it suitable for a wide range of applications requiring reliable and compact memory solutions.

• Data logging in embedded systems
• Configuration and calibration data storage
• Firmware or parameter storage in microcontroller-based systems
• Industrial automation and control systems
• Consumer electronics requiring small-scale non-volatile memory

The following table outlines the key technical details of the 25LC160:

The 25LC160 is available in an 8-pin package. The pinout and descriptions are as follows:

1. Power Supply: Connect the VCC pin to a power source (2.5V to 5.5V) and the VSS pin to ground.
2. SPI Connections:
   • Connect the CS pin to a GPIO pin on the microcontroller to enable/disable the EEPROM.
   • Connect the SCK pin to the SPI clock pin of the microcontroller.
   • Connect the SI pin to the SPI MOSI (Master Out Slave In) pin.
   • Connect the SO pin to the SPI MISO (Master In Slave Out) pin.
3. Optional Pins:
   • If write protection is required, pull the WP pin low.
   • If the hold feature is needed, connect the HOLD pin to a GPIO pin or pull it high if unused.
4. SPI Configuration: Configure the SPI interface on the microcontroller with the following settings:
   • Clock polarity (CPOL): 0
   • Clock phase (CPHA): 0
   • Data order: MSB first
5. Read/Write Operations:
   • To write data, send the WRITE instruction (0x02) followed by the memory address and data bytes.
   • To read data, send the READ instruction (0x03) followed by the memory address and read the data bytes.

• Ensure the CS pin is pulled high when the EEPROM is not in use to avoid unintentional operations.
• Avoid exceeding the maximum clock frequency of 10 MHz to ensure reliable communication.
• Use decoupling capacitors (e.g., 0.1 µF) near the VCC pin to stabilize the power supply.
• Allow sufficient time for the write cycle (5 ms) to complete before initiating another write operation.
• Use the WP pin to protect critical data from accidental overwrites.

Below is an example of interfacing the 25LC160 with an Arduino UNO to write and read data:

#include <SPI.h>

// Pin definitions
const int CS_PIN = 10; // Chip Select pin connected to Arduino pin 10

void setup() {
  Serial.begin(9600);
  SPI.begin();
  pinMode(CS_PIN, OUTPUT);
  digitalWrite(CS_PIN, HIGH); // Ensure CS is high initially
}

void loop() {
  // Write data to EEPROM
  writeEEPROM(0x0000, 0x42); // Write 0x42 to address 0x0000
  delay(10); // Wait for write cycle to complete

  // Read data from EEPROM
  byte data = readEEPROM(0x0000);
  Serial.print("Read Data: 0x");
  Serial.println(data, HEX);

  while (1); // Stop execution
}

void writeEEPROM(unsigned int address, byte data) {
  digitalWrite(CS_PIN, LOW); // Select the EEPROM
  SPI.transfer(0x02);        // Send WRITE instruction
  SPI.transfer((address >> 8) & 0xFF); // Send high byte of address
  SPI.transfer(address & 0xFF);        // Send low byte of address
  SPI.transfer(data);        // Send data byte
  digitalWrite(CS_PIN, HIGH); // Deselect the EEPROM
}

byte readEEPROM(unsigned int address) {
  digitalWrite(CS_PIN, LOW); // Select the EEPROM
  SPI.transfer(0x03);        // Send READ instruction
  SPI.transfer((address >> 8) & 0xFF); // Send high byte of address
  SPI.transfer(address & 0xFF);        // Send low byte of address
  byte data = SPI.transfer(0x00); // Read data byte
  digitalWrite(CS_PIN, HIGH); // Deselect the EEPROM
  return data;
}

1. No Data Read/Write:

   • Ensure the CS pin is correctly toggled (low during operations, high otherwise).
   • Verify SPI connections and ensure the correct pins are used for MOSI, MISO, and SCK.
   • Check the power supply voltage and ensure it is within the operating range (2.5V to 5.5V).

2. Corrupted Data:

   • Ensure the write cycle time (5 ms) is respected before initiating another operation.
   • Use decoupling capacitors to stabilize the power supply.

3. Device Not Responding:

   • Verify the SPI clock frequency does not exceed 10 MHz.
   • Check the WP and HOLD pins; ensure they are configured correctly.

Q1: Can I use the 25LC160 with a 3.3V microcontroller?
A1: Yes, the 25LC160 operates within a voltage range of 2.5V to 5.5V, making it compatible with 3.3V systems.

Q2: How many write/erase cycles can the 25LC160 handle?
A2: The device supports up to 1,000,000 write/erase cycles, ensuring long-term reliability.

Q3: What happens if power is lost during a write operation?
A3: The data being written may be corrupted. It is recommended to use a power-fail detection circuit to prevent such issues.

Q4: Can I use multiple 25LC160 devices on the same SPI bus?
A4: Yes, multiple devices can share the same SPI bus. Assign a unique CS pin for each device to select them individually.