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Unable to program 01h register in CDCE925?

Kalpesh Krishna
Prodigy 20 points
Other Parts Discussed in Thread: CDCE925

We are programming the CDCE925 http://www.ti.com/lit/ds/symlink/cdce925.pdf

Since 01h has some read-only bits too, what's the correct way to program the lower 4 bits of this register? We need to set the slave address's A0 and A1 bit.

On attempting to program the 01h register with values 0x03 or 0x13, the device no longer accepts I2C communication. We had to power down/up the device.

  • 0
    TI__Expert 5325 points
    Hello Kalpesh,
    the read-only bits are hard-wired. Please use zero for the read-only bits of offset 0x01.
    Please be careful when you implement changes here - this register contains the programmable LSBs of the I2C slave address.
    Reg01[1:0]="SLAVE_ADR" Thus you need to adapt the slave address you are using.
    Moreover a bitfield to use very carefully is Reg01[5]="EELOCK". When you write a '1' to this bitfield the EEPROM is locked forever.
    The issue with your test writes is not the '1' in the upper nibble, it is the '3' in the lower nibble. The default LSBs are '0'.

    Best regards,
    Patrick