psd835g2 STMicroelectronics, psd835g2 Datasheet - Page 12

• Manufacturer Part Number: psd835g2
• Description: Configurable Memory System On A Chip For 8-bit Microcontrollers
• Manufacturer: STMicroelectronics

Description
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In-application programming (IAP)
Two independent Flash memory arrays are included so that the MCU can execute code from
one while erasing and programming the other. Robust product firmware updates in the field
are possible over any communications channel (CAN, Ethernet, UART, J1850, etc.) using
this unique architecture. Designers are relieved of the following problems:
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Simultaneous READ and WRITE to Flash memory
How can the MCU program the same memory from which it is 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 extremely 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 80C51 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™
PSDsoft, 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 takes you through the remainder of the design with
point and click entry, covering PSD selection, pin definitions, programmable logic inputs and
outputs, 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: FlashLINK (JTAG) and PSDpro.
Simultaneous READ and WRITE to Flash memory
Complex memory mapping
Separate program and data space
PSD835G2