psd4235g2 STMicroelectronics, psd4235g2 Datasheet - Page 13

• Manufacturer Part Number: psd4235g2
• Description: Flash In-system Programmable Isp Peripherals For 16-bit Mcus 5v Supply
• Manufacturer: STMicroelectronics

PSD4235G2
1.2.1
1.2.2
1.2.3
1.3
Simultaneous READ and WRITE to Flash memory
How can the MCU program the same memory from which it executing code? It cannot. The
PSD allows the MCU to operate the two Flash memory blocks concurrently, reading code
from one while erasing and programming the other during IAP.
Complex memory mapping
How can I map these two memories efficiently? A programmable Decode PLD (DPLD) is
embedded in the PSD. The concurrent PSD memories can be mapped anywhere in MCU
address space, segment by segment with extermely high address resolution. As an option,
the secondary Flash memory can be swapped out of the system memory map when IAP is
complete. A built-in page register breaks the MCU address limit.
Separate Program and Data space
How can I write to Flash memory while it resides in Program space during field firmware
updates? My 80C51XA will not allow it. The PSD provides means to reclassify Flash
memory as Data space during IAP, then back to Program space when complete.
PSDsoft™ Express
PSDsoft Express, a software development tool from ST, guides you through the design
process step-by-step making it possible to complete an embedded MCU design capable of
ISP/IAP in just hours. Select your MCU and PSDsoft Express takes you through the
remainder of the design with point and click entry, covering PSD selection, pin definitions,
programmable logic inputs and outpus, MCU memory map definition, ANSI-C code
generation for your MCU, and merging your MCU firmware with the PSD design. When
complete, two different device programmers are supported directly from PSDsoft Express:
FlashLINK (JTAG) and PSDpro.
Summary description
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