PSD835G2-70UI datasheet(73/110 Pages) STMICROELECTRONICS

73 / 110 page

PSD8XX Family

PSD835G2

The

PSD835G2

Functional

Blocks

(cont.)

9.6.1 Standard JTAG Signals (cont.)

The PSD835G2 supports JTAG-ISP commands, but not Boundary Scan. ST's

PSDsoft software tool and FlashLink JTAG programming cable implement these JTAG-ISC

commands.

9.6.2 JTAG Extensions

TSTAT and TERR are two JTAG extension signals enabled by a JTAG command

received over the four standard JTAG pins (TMS, TCK, TDI, and TDO). They are used to

speed programming and erase functions by indicating status on PSD pins instead of

having to scan the status out serially using the standard JTAG channel. See Application

Note 54.

TERR will indicate if an error has occurred when erasing a sector or programming in

Flash memory. This signal will go low (active) when an error condition occurs, and stay

low until a special JTAG command is executed or a chip reset pulse is received after an

“ISC-DISABLE” command.

TSTAT behaves the same as the Rdy/Bsy signal described in section 9.1.1.2. TSTAT will

be high when the PSD835G2 device is in read array mode (Flash memory and Boot Block

contents can be read). TSTAT will be low when Flash memory programming or erase

cycles are in progress, and also when data is being written to the Flash Boot Block.

TSTAT and TERR can be configured as open-drain type signals with a JTAG command.

9.6.3 Security and Flash Memories Protection

When the security bit is set, the device cannot be read on a device programmer or through

the JTAG Port. When using the JTAG Port, only a full chip erase command is allowed.

All other program/erase/verify commands are blocked. Full chip erase returns the part to a

non-secured blank state. The Security Bit can be set in PSDsoft.

All Flash Memory and Boot sectors can individually be sector protected against erasures.

The sector protect bits can be set in PSDsoft.

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