Summit S93WD463 manual Erase/Write Enable and Disable, Erase All, Write All, Continuous Read

S93WD462/S93WD463

Erase

Upon receiving an ERASE command and address, the CS (Chip Select) pin must be deselected for a minimum of 250ns (tCSMIN). The falling edge of CS will start the auto erase cycle of the selected memory location. The ready/busy status of the S93WD462/WD463 can be determined by selecting the device and polling the DO pin. Once cleared, the content of a cleared location returns to a logical “1” state.

Erase/Write Enable and Disable

The S93WD462/WD463 powers up in the write disable state. Any writing after power-up or after an EWDS (write disable) instruction must first be preceded by the EWEN (write enable) instruction. Once the write in- struction is enabled, it will remain enabled until power to the device is removed, or the EWDS instruction is sent. The EWDS instruction can be used to disable all S93WD462/WD463 write and clear instructions, and will prevent any accidental writing or clearing of the device. Data can be read normally from the device regardless of the write enable/disable status.

Erase All

Upon receiving an ERAL command, the CS (Chip Se- lect) pin must be deselected for a minimum of 250ns (tCSMIN). The falling edge of CS will start the self clocking clear cycle of all memory locations in the device. The clocking of the SK pin is not necessary after the device has entered the self clocking mode. The ready/busy status of the S93WD462/WD463 can be determined by selecting the device and polling the DO pin. Once cleared, the contents of all memory bits will be in a logical “1” state.

Write All

Upon receiving a WRAL command and data, the CS (Chip Select) pin must be deselected for a minimum of 250ns (tCSMIN). The falling edge of CS will start the self clocking data write to all memory locations in the device. The clocking of the SK pin is not necessary after the device has entered the self clocking mode. The ready/ busy status of the S93WD462/WD463 can be deter- mined by selecting the device and polling the DO pin. It is not necessary for all memory locations to be cleared before the WRAL command is executed.

Page Write

93WD462 - Assume WEN has been issued. The host will then take CS high, and begin clocking in the start bit, write command and 7-bit address immediately followed by the first byte of data to be written. The host can then continue clocking in 8-bit bytes of data with each byte to be written to the next higher address. Internally the address pointer is incremented after receiving each group of eight clocks; however, once the address counter reaches xxx 1111 it will roll over to xxx 0000 with the next clock. After the last bit is clocked in no internal write operation will occur until CS is brought low.

93WD463 - Assume WEN has been issued. The host will then take CS high, and begin clocking in the start bit, write command and 6-bit address immediately followed by the first 16-bit word of data to be written. The host can then continue clocking in 16-bit words of data with each word to be written to the next higher

address. Internally the address pointer is incremented after receiving each group of sixteen clocks; however, once the address counter reaches xxx x111 it will roll over to xx x000 with the next clock. After the last bit is clocked in no internal write operation will occur until CS is brought low.

Continuous Read

This begins just like a standard read with the host issuing a read instruction and clocking out the data byte [word]. If the host then keeps CS high and continues generating clocks on SK, the S93WD462/ WD463 will output data from the next higher address location. The S93WD462/WD463 will continue incrementing the address and outputting data so long as CS stays high. If the highest address is reached, the address counter will roll over to address 0000. CS going low will reset the instruction register and any subsequent read must be initiated in the normal man- ner of issuing the command and address.

4 2029 2.2 1/23/01 SUMMIT MICROELECTRONICS, Inc.