DSM2180F3 datasheet(25/63 Pages) STMICROELECTRONICS

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DSM2180F3

DSM Security Bit

A programmable security bit in the DSM protects

its contents from unauthorized viewing and copy-

ing. When set, the security bit will block access of

programming devices (JTAG or others) to the

DSM Flash memory and PLD configuration. The

only way to defeat the security bit is to erase the

entire DSM device, after which the device is blank

and may be used again. The DSP will always have

access to Flash memory contents through the 8-bit

data port even while the security bit is set. The

DSP can read the status of the security bit (but it

cannot change it) by reading the Device Security

csiop block as defined in Table 8.

Reset Flash

The Reset Flash instruction sequence resets the

internal memory logic state machine and puts

Flash memory into Read Array mode. It consists of

one write cycle (see Table 5). It must be executed

after:

– Reading the Flash Protection Status or Flash ID

– An Error condition has occurred (and the device

has set the Error Flag (DQ5) bit to 1) during a

Flash memory Program or Erase cycle.

The Reset Flash instruction sequence puts the

Flash memory back into normal Read Array mode.

It may take the Flash memory up to a few millisec-

onds to complete the Reset cycle. The Reset

Flash instruction sequence is ignored when it is is-

sued during a Program or Bulk Erase cycle of the

Flash memory. The Reset Flash instruction se-

quence aborts any on-going Sector Erase cycle,

and returns the Flash memory to the normal Read

Array mode within a few milliseconds.

Page Register

The 8-bit Page Register increases the addressing

capability of the DSP by a factor of up to 256. The

contents of the register can also be read by the

DSP. The outputs of the Page Register (PG0-

PG7) are inputs to the DPLD decoder and can be

included in the Sector Select (

FS0-FS7) equa-

tions. See Figure 12.

If memory paging is not needed, or if not all 8 page

these bits may be used in the CPLD for general

logic. The eight flip-flops in the register are con-

nected to the internal data bus D0-D7. The DSP

can write to or read from the Page Register. The

Page Register can be accessed at address loca-

tion

csiop + E0h. Page Register outputs are

cleared to logic 0 at reset.

Figure 12. Page Register

PLDs

The PLDs bring programmable logic to the device.

After specifying the logic for the PLDs using PSD-

soft Express, the logic is programmed into the de-

vice and available upon Power-up.

The PLDs have selectable levels of performance

and power consumption.

The device contains two PLDs: the Decode PLD

(DPLD), and the Complex PLD (CPLD), as shown

in Figure 13.

Table 9. DPLD and CPLD Inputs

Note: 1. DSP address lines A16, A17, and others may enter the

DSM device on any pin on ports B, C, or D. See Figure 6

for recommended connections.

2. Additional DSP control signals may enter the DMS device

on any pin on Ports B, C, or D. See Figure 6 for recom-

mended connections.

Input Source

Input Name

Number

Signals

DSP Address Bus1

A15-A0

DSP Control Signals2

CNTL2-CNTL0

Reset

RST

PortB Input Macrocells

PB7-PB0

PortC Input Macrocells

PC7-PC0

Port D Inputs

PD2-PD0

Page Register

PG7-PG0

Macrocell AB

Feedback

MCELLAB FB7-0

Macrocell BC

Feedback

MCELLBC FB7-0

Flash memory

Program Status Bit

Ready/Busy

RESET

D 0-D 7

R/W

PAGE

PGR0

PGR1

PGR2

PGR3

DPLD

AND

CPLD

INTERNAL

SELECTS

AND LOGIC

PLD

PGR4

PGR5

PGR6

PGR7

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