M95512-A125 Datasheet, PDF (20/44 Pages) STMicroelectronics – Automotive 512-Kbit serial SPI bus EEPROMs with high-speed clock

Instructions
M95512-A125 M95512-A145
4.6
Write to Memory Array (WRITE)
The WRITE instruction is used to write new data in the memory.
As shown in Figure 10, to send this instruction to the device, Chip Select (S) is first driven
low. The bits of the instruction byte, address bytes, and at least one data byte are then
shifted in (MSB first), on Serial Data Input (D). The instruction is terminated by driving Chip
Select (S) high at a data byte boundary. Figure 10 shows a single byte write.
Figure 10. Byte Write (WRITE) sequence
3
                      
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 "IT!DDRESS
$ATA"YTE
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(IGH)MPEDANCE
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1. Depending on the memory size, as shown in Table 7, the most significant address bits are Don’t Care.
A Page write is used to write several bytes inside a page, with a single internal Write cycle.
For a Page write, Chip Select (S) has to remain low, as shown in Figure 11, so that the next
data bytes are shifted in. Each time a new data byte is shifted in, the least significant bits of
the internal address counter are incremented. If the address counter exceeds the page
boundary (the page size is 128 byte), the internal address pointer rolls over to the beginning
of the same page where next data bytes will be written. If more than 128 byte are received,
only the last 128 byte are written.
Note:
For both Byte write and Page write, the self-timed Write cycle starts from the rising edge of
Chip Select (S), and continues for a period t_W (as specified in Table 15).
The instruction is discarded, and is not executed, under the following conditions:
• if a Write cycle is already in progress
• if the addressed page is in the region protected by the Block Protect (BP1 and BP0)
bits
• if one of the conditions defined in Section 3.4.1 is not satisfied
The self-timed Write cycle t_W is internally executed as a sequence of two consecutive
events: [Erase addressed byte(s)], followed by [Program addressed byte(s)]. An erased bit
is read as “0” and a programmed bit is read as “1”.
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