PSD913212JIT ST Microelectronics, PSD913212JIT Datasheet - Page 21

• Manufacturer Part Number: PSD913212JIT
• Description: Flash In-System Programmable ISP Peripherals For 8-bit MCUs
• Manufacturer: ST Microelectronics

Preliminary Information
The
PSD9XX
Functional
Blocks
(cont.)
9.1.1.3.1 Instructions
An instruction is defined as a sequence of specific operations. Each received byte is
sequentially decoded by the PSD and not executed as a standard write operation. The
instruction is executed when the correct number of bytes are properly received and the
time between two consecutive bytes is shorter than the time-out value. Some instructions
are structured to include read operations after the initial write operations.
The sequencing of any instruction must be followed exactly. Any invalid combination of
instruction bytes or time-out between two consecutive bytes while addressing Flash
memory will reset the device logic into a read array mode (Flash memory reads like a
ROM device).
The PSD9XX main Flash and Secondary Flash support these instructions (see Table 9):
These instructions are detailed in Table 9. For efficient decoding of the instructions, the
first two bytes of an instruction are the coded cycles and are followed by a command byte
or confirmation byte. The coded cycles consist of writing the data AAh to address X555h
during the first cycle and data 55h to address XAAAh during the second cycle. Address
lines A15-A12 are don’t care during the instruction write cycles. However, the appropriate
sector select signal (FSi or CSBOOTi) must be selected.
The main Flash and the Secondary Flash Block have the same set of instructions (except
Read main Flash ID). The chip selects of the Flash memory will determine which Flash will
receive and execute the instruction. The main Flash is selected if any one of the FS0-7 is
active, and the secondary Flash Block is selected if any one of the CSBOOT0-3 is active.
Erase memory by chip or sector
Suspend or resume sector erase
Program a byte
Reset to read array mode
Read Main Flash Identifier value
Read sector protection status
Bypass Instruction (PSD934F2 and PSD954F2 only)
PSD9XX Family
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