How to Use M93C46: Examples, Pinouts, and Specs

The M93C46 is a 1K-bit electrically erasable programmable read-only memory (EEPROM) manufactured by STMicroelectronics. It operates with a serial interface, making it ideal for applications requiring compact, non-volatile memory storage. The M93C46 supports both 8-bit and 16-bit data organization modes, providing flexibility for various use cases.

• Configuration data storage in embedded systems
• Calibration data storage for sensors
• Non-volatile memory for microcontroller-based designs
• Secure storage for device identification or authentication keys
• Data logging in industrial and automotive systems

The M93C46 is available in an 8-pin package. Below is the pinout and description:

1. Power Supply: Connect the VCC pin to a stable power source (2.5V to 5.5V) and the GND pin to ground.
2. Chip Select: Use the CS pin to enable or disable communication with the EEPROM. Pull it high to enable communication.
3. Clock Signal: Provide a clock signal to the SK pin to synchronize data transfer.
4. Data Input/Output: Use the DI pin to send data to the EEPROM and the DO pin to read data from it.
5. Organization Mode: Set the ORG pin to configure the memory organization:
   • Connect to GND for 16-bit word organization.
   • Connect to VCC for 8-bit byte organization.

• Pull-up Resistors: Use pull-up resistors on the CS and DI lines to ensure proper logic levels.
• Write Protection: Avoid accidental writes by ensuring the CS pin is low when not in use.
• Timing Requirements: Adhere to the timing specifications in the datasheet for reliable operation.
• Decoupling Capacitor: Place a 0.1 µF decoupling capacitor near the VCC pin to filter noise.

Below is an example of how to interface the M93C46 with an Arduino UNO to write and read data.

#include <SPI.h>

// Define pin connections
const int CS_PIN = 10;

void setup() {
  // Initialize serial communication for debugging
  Serial.begin(9600);

  // Set up SPI and chip select pin
  pinMode(CS_PIN, OUTPUT);
  digitalWrite(CS_PIN, HIGH); // Disable chip by default
  SPI.begin();
}

void loop() {
  // Example: Write data to M93C46
  writeEEPROM(0x00, 0x1234); // Write 16-bit data to address 0x00
  delay(10); // Wait for write cycle to complete

  // Example: Read data from M93C46
  uint16_t data = readEEPROM(0x00);
  Serial.print("Read Data: 0x");
  Serial.println(data, HEX);

  while (1); // Stop execution
}

void writeEEPROM(uint8_t address, uint16_t data) {
  digitalWrite(CS_PIN, LOW); // Enable chip
  SPI.transfer(0x40 | (address & 0x3F)); // Send WRITE opcode and address
  SPI.transfer(data >> 8); // Send high byte of data
  SPI.transfer(data & 0xFF); // Send low byte of data
  digitalWrite(CS_PIN, HIGH); // Disable chip
}

uint16_t readEEPROM(uint8_t address) {
  digitalWrite(CS_PIN, LOW); // Enable chip
  SPI.transfer(0x80 | (address & 0x3F)); // Send READ opcode and address
  uint8_t highByte = SPI.transfer(0x00); // Read high byte
  uint8_t lowByte = SPI.transfer(0x00); // Read low byte
  digitalWrite(CS_PIN, HIGH); // Disable chip
  return (highByte << 8) | lowByte; // Combine high and low bytes
}

1. No Data Output on DO Pin:

   • Ensure the CS pin is pulled high during communication.
   • Verify the clock signal on the SK pin is within the specified frequency range.

2. Write Operation Fails:

   • Check if the power supply voltage is stable and within the operating range.
   • Ensure the write cycle time (5 ms) is respected before initiating another operation.

3. Incorrect Data Read:

   • Verify the ORG pin configuration matches the intended data organization (8-bit or 16-bit).
   • Check for noise or signal integrity issues on the SPI lines.

Q: Can the M93C46 operate at 3.3V?
A: Yes, the M93C46 supports an operating voltage range of 2.5V to 5.5V, making it compatible with 3.3V systems.

Q: How do I protect the EEPROM from accidental writes?
A: Keep the CS pin low when not in use and ensure proper handling of the write enable/disable commands.

Q: What is the maximum clock frequency for the M93C46?
A: The maximum clock frequency is 2 MHz when operating at 5V. For lower voltages, refer to the datasheet for specific limits.