PSD853F2VA-12UI View Datasheet(PDF) - STMicroelectronics
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PSD853F2VA-12UI Datasheet PDF : 128 Pages
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PSD architectural overview
3
PSD architectural overview
PSD8XXFX
PSD devices contain several major functional blocks. Figure 4 shows the architecture of the
PSD device family. The functions of each block are described briefly in the following
sections. Many of the blocks perform multiple functions and are user configurable.
3.1
Memory
Each of the memory blocks is briefly discussed in the following paragraphs. A more detailed
discussion can be found in Section 6.1: Memory blocks.
The 1 Mbit or 2 Mbit (128K x 8, or 256K x 8) Flash memory is the primary memory of the
PSD. It is divided into 8 equally-sized sectors that are individually selectable.
The optional 256 Kbit (32K x 8) secondary Flash memory is divided into 4 equally-sized
sectors. Each sector is individually selectable.
The optional SRAM is intended for use as a scratch-pad memory or as an extension to the
MCU SRAM.
Each sector of memory can be located in a different address space as defined by the user.
The access times for all memory types includes the address latching and DPLD decoding
time.
3.2
Page register
The 8-bit Page register expands the address range of the MCU by up to 256 times. The
paged address can be used as part of the address space to access external memory and
peripherals, or internal memory and I/O. The Page register can also be used to change the
address mapping of sectors of the Flash memories into different memory spaces for IAP.
3.3
PLDs
The device contains two PLDs, the Decode PLD (DPLD) and the Complex PLD (CPLD), as
shown in Table 4, each optimized for a different function. The functional partitioning of the
PLDs reduces power consumption, optimizes cost/performance, and eases design entry.
The DPLD is used to decode addresses and to generate Sector Select signals for the PSD
internal memory and registers. The DPLD has combinatorial outputs. The CPLD has 16
Output macrocells (OMC) and 3 combinatorial outputs. The PSD also has 24 input
macrocells (IMC) that can be configured as inputs to the PLDs. The PLDs receive their
inputs from the PLD input bus and are differentiated by their output destinations, number of
product terms, and macrocells.
The PLDs consume minimal power. The speed and power consumption of the PLD is
controlled by the Turbo Bit in PMMR0 and other bits in the PMMR2. These registers are set
by the MCU at run-time. There is a slight penalty to PLD propagation time when invoking the
power management features.
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Doc ID 7833 Rev 7
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