Quad-Serial Configuration (EPCQ) Devices Datasheet

ID 683078
Date 1/23/2020
Document Table of Contents

1.7.9. Write Bytes Operation (02h)

This operation allows bytes to be written to the memory. You must execute the write enable operation before the write bytes operation. After the write bytes operation is completed, the write enable latch bit in the status register is set to 0.

When you execute the write bytes operation, you shift in the write bytes operation code, followed by a 3-byte addressing mode (A[23..0]) or a 4-byte addressing mode (A[31..0]), and at least one data byte on the DATA0 pin. If the eight LSBs (A[7..0]) are not all 0, all sent data that goes beyond the end of the current page is not written into the next page. Instead, this data is written at the start address of the same page. You must ensure the nCS signal is set low during the entire write bytes operation.

Figure 15. Write Bytes Operation Timing DiagramTo access the entire EPCQ256 or EPCQ512/A memory, use 4-byte addressing mode. In the 4-byte addressing mode, the address width is 32-bit address.

If more than 256 data bytes are shifted into the EPCQ device with a write bytes operation, the previously latched data is discarded and the last 256 bytes are written to the page. However, if less than 256 data bytes are shifted into the EPCQ device, they are guaranteed to be written at the specified addresses and the other bytes of the same page are not affected.

The device initiates a self-timed write cycle immediately after the nCS signal is driven high. For details about the self-timed write cycle time, refer to tWB in the related information below. You must account for this amount of delay before another page of memory is written. Alternatively, you can check the write in progress bit in the status register by executing the read status operation while the self-timed write cycle is in progress. The write in progress bit is set to 1 during the self-timed write cycle and 0 when it is complete.

Note: You must erase all the memory bytes of EPCQ devices before you implement the write bytes operation. You can erase all the memory bytes by executing the erase sector operation in a sector or the erase bulk operation throughout the entire memory