参数资料
型号: PSD4235F1-C-90MI
厂商: 意法半导体
英文描述: Flash In-System-Programmable Peripherals for 16-Bit MCUs
中文描述: Flash在系统可编程外设的16位微控制器
文件页数: 19/93页
文件大小: 503K
代理商: PSD4235F1-C-90MI
PSD4000 Series
Preliminary Information
16
9.1.1.3 Memory Operation
The main Flash and secondary Flash memories are addressed through the microcontroller
interface on the PSD4000 device. The microcontroller can access these memories in one
of two ways:
J
The microcontroller can execute a typical bus write or read
operation
just as it would
if accessing a RAM or ROM device using standard bus cycles.
J
The microcontroller can execute a specific
instruction
that consists of several write
and read operations. This involves writing specific data patterns to special addresses
within the Flash to invoke an embedded algorithm. These instructions are summarized
in Table 8.
Typically, Flash memory can be read by the microcontroller using read operations, just
as it would read a ROM device. However, Flash memory can only be erased and
programmed with specific instructions. For example, the microcontroller cannot write a
single word directly to Flash memory as one would write a word to RAM. To program a
word into Flash memory, the microcontroller must execute a program instruction sequence,
then test the status of the programming event. This status test is achieved by a read
operation or polling the Rdy/Busy pin (PE4).
The Flash memory can also be read by using special instructions to retrieve particular
Flash device information (sector protect status and ID).
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 PSD4000 main Flash and secondary Flash support these instructions (see Table 8):
J
Erase memory by chip or sector
J
Suspend or resume sector erase
J
Program a word
J
Reset to read array mode
J
Read Main Flash Identifier value
J
Read sector protection status
J
Bypass Instruction
These instructions are detailed in Table 8. 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 byte AAh to address
XAAAh during the first cycle and data byte 55h to address X554h during the second cycle
(unless the Bypass Instruction feature is used. See 9.1.1.7). 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.
The
PSD4000
Functional
Blocks
(cont.)
相关PDF资料
PDF描述
PSD4235F1-C-90U Flash In-System-Programmable Peripherals for 16-Bit MCUs
PSD4235F1-C-90UI Flash In-System-Programmable Peripherals for 16-Bit MCUs
PSD4235F2-15UI Flash In-System-Programmable Peripherals for 16-Bit MCUs
PSD4235F2-70UI Flash In-System-Programmable Peripherals for 16-Bit MCUs
PSD4235F2-90B81 Flash In-System-Programmable Peripherals for 16-Bit MCUs
相关代理商/技术参数
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