I2C - DS1307 - 24C02

1. No Communication (ACK Not Received)

Q: My device doesn’t respond to addresses.
A:

• Verify I2C_Init() was called first
• Check pull-up resistors (4.7kΩ on SDA/SCL)
• Confirm slave address matches datasheet (7-bit vs 8-bit)
• Use logic analyzer to check signal integrity

2. Signal Glitches

Q: Random NACKs or corrupted data.
A:

• Add small delays (_nop_()) between SCL/SDA transitions
• Ensure power supply is stable (>100mA for bus)
• Keep I2C traces short (<30cm)

3. Clock Stretching Issues

Q: Master hangs waiting for slave.
A:

• Implement timeout in I2C_Read():
  
  C

  u8 timeout = 255; while(SCL == 0 &amp;&amp; timeout--);// Prevent infinite wait

  1 2	u8 timeout = 255; while(SCL == 0 && timeout--);// Prevent infinite wait

4. Multi-Master Conflicts

Q: Bus locks up with multiple masters.
A:

• Add bus arbitration check after I2C_Start():
  
  C

  if(SDA == 0) { I2C_Stop(); return; }

  1 2 3 4

  if(SDA == 0) { I2C_Stop(); return; }

5. Speed Optimization

Q: How to increase I2C speed?
A:

• Reduce _nop_() delays (minimum 4.7µs for 100kHz)
• Use hardware I2C if available