PSD81XFX, PSD83XF2, PSD85XF2
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JTAG Extensions
TSTAT and TERR are two JTAG extension signals
enabled by an “ISC_ENABLE” command received
over the four standard JTAG signals (TMS, TCK,
TDI, and TDO). They are used to speed Program
and Erase cycles by indicating status on
PSD8XXFX signals instead of having to scan the
status out serially using the standard JTAG chan-
nel. See Application Note AN1153
TERR indicates if an error has occurred when
erasing a sector or programming a byte in Flash
memory. This signal goes Low (active) when an
Error condition occurs, and stays Low until an
“ISC_CLEAR” command is executed or a chip Re-
set (RESET) pulse is received after an
“ISC_DISABLE” command.
TSTAT behaves the same as Ready/Busy de-
scribed in the section entitled “Ready/Busy (PC3)”,
on page 18. TSTAT is High when the PSD8XXFX
device is in READ Mode (primary and secondary
Flash memory contents can be read). TSTAT is
Low when Flash memory Program or Erase cycles
are in progress, and also when data is being writ-
ten to the secondary Flash memory.
TSTAT and TERR can be configured as open-
drain type signals during an “ISC_ENABLE” com-
mand. This facilitates a wired-OR connection of
TSTAT signals from multiple PSD8XXFX devices
and a wired-OR connection of TERR signals from
those same devices. This is useful when several
PSD8XXFX devices are “chained” together in a
JTAG environment.
Security and Flash memory 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 and Verify commands
are blocked. Full Chip Erase returns the part to a
non-secured blank state. The Security Bit can be
set in PSDsoft Express Configuration.
All primary and secondary Flash memory sectors
can individually be sector protected against era-
sures. The sector protect bits can be set in PSD-
soft Express Configuration.
INITIAL DELIVERY STATE
When delivered from ST, the PSD8XXFX device
has all bits in the memory and PLDs set to 1. The
PSD8XXFX Configuration Register bits are set to
0. The code, configuration, and PLD logic are
loaded using the programming procedure. Infor-
mation for programming the device is available di-
rectly from ST. Please contact your local sales
representative.
Table 35. JTAG Enable Register
Note: 1. The state of Reset (RESET) does not interrupt (or prevent) JTAG operations if the JTAG signals are dedicated by an NVM Config-
uration bit (via PSDsoft Express). However, Reset (RESET) prevents or interrupts JTAG operations if the JTAG enable register is
used to enable the JTAG signals.
Bit 0
JTAG_Enable
0 = off JTAG port is disabled.
1 = on JTAG port is enabled.
Bit 1
X
0
Not used, and should be set to zero.
Bit 2
X
0
Not used, and should be set to zero.
Bit 3
X
0
Not used, and should be set to zero.
Bit 4
X
0
Not used, and should be set to zero.
Bit 5
X
0
Not used, and should be set to zero.
Bit 6
X
0
Not used, and should be set to zero.
Bit 7
X
0
Not used, and should be set to zero.