7.5.2 Clear RSWP

Similar to the Set RSWP command, the reversible write protection on all quadrants can be reversed or unprotected by transmitting the Clear RSWP command. The Clear RSWP sequence requires the master to send a Start condition followed by sending a device address byte of ‘01100110’ (66h) with the R/W bit set to ‘0’.

The AT34C04 should respond with an ACK. The master transmits a word address byte and data bytes with ‘don’t care’ values. The AT34C04 will respond with either an ACK or NACK to both the word address and data word. In conjunction with sending the protocol, the A0 pin must be connected to V_HV for the duration of the Clear RSWP command (see Figure 7-5). To end the Clear RSWP sequence, the master sends a Stop condition.

Note: The write protection of individual quadrants cannot be reversed separately, and executing the Clear RSWP command will clear the write protection on all four quadrants leaving all quadrants with no software write protection.