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PSD813F2, PSD833F2, PSD834F2, PSD853F2, PSD854F2
PROGRAMMING IN-CIRCUIT USING THE JTAG SERIAL INTERFACE
The JTAG Serial Interface block can be enabled
on Port C (see
Table 34., page 70
). All memory
blocks (primary and secondary Flash memory),
PLD logic, and PSD Configuration Register bits
may be programmed through the JTAG Serial In-
terface block. A blank device can be mounted on
a printed circuit board and programmed using
JTAG.
The standard JTAG signals (IEEE 1149.1) are
TMS, TCK, TDI, and TDO. Two additional signals,
TSTAT and TERR, are optional JTAG extensions
used to speed up Program and Erase cycles.
By default, on a blank PSD (as shipped from the
factory or after erasure), four pins on Port C are
enabled for the basic JTAG signals TMS, TCK,
TDI, and TDO
.
See Application Note
AN1153
for more details on
JTAG In-System Programming (ISP).
Standard JTAG Signals
The standard JTAG signals (TMS, TCK, TDI, and
TDO) can be enabled by any of three different con-
ditions that are logically ORed. When enabled,
TDI, TDO, TCK, and TMS are inputs, waiting for a
JTAG serial command from an external JTAG con-
troller device (such as FlashLINK or Automated
Test Equipment). When the enabling command is
received, TDO becomes an output and the JTAG
channel is fully functional inside the PSD. The
same command that enables the JTAG channel
may optionally enable the two additional JTAG sig-
nals, TSTAT and TERR.
The following symbolic logic equation specifies the
conditions enabling the four basic JTAG signals
(TMS, TCK, TDI, and TDO) on their respective
Port C pins. For purposes of discussion, the logic
label JTAG_ON is used. When JTAG_ON is true,
the four pins are enabled for JTAG. When
JTAG_ON is false, the four pins can be used for
general PSD I/O.
JTAG_ON = PSDsoft_enabled +
/* An NVM configuration bit inside the
PSD is set by the designer in the
PSDsoft Express Configuration utility.
This dedicates the pins for JTAG at all
times (compliant with IEEE 1149.1 */
Microcontroller_enabled +
/* The microcontroller can set a bit at
run-time by writing to the PSD
register, JTAG Enable. This register is
located at address CSIOP + offset C7h.
Setting the JTAG_ENABLE bit in this
register will enable the pins for JTAG
use. This bit is cleared by a PSD reset
or the microcontroller. See
Table
35., page 71
for bit definition. */
PSD_product_term_enabled;
/* A dedicated product term (PT) inside
the PSD can be used to enable the JTAG
pins. This PT has the reserved name
JTAGSEL. Once defined as a node in
PSDabel, the designer can write an
equation for JTAGSEL. This method is
used when the Port C JTAG pins are
multiplexed with other I/O signals. It
is recommended to logically tie the
node JTAGSEL to the JEN\ signal on the
Flashlink cable when multiplexing JTAG
signals. See Application Note 1153 for
details. */
The state of the PSD Reset (RESET) signal does
not interrupt (or prevent) JTAG operations if the
JTAG pins are dedicated by an NVM configuration
bit (via PSDsoft Express). However, Reset (RE-
SET) will prevent or interrupt JTAG operations if
the JTAG enable register is used to enable the
JTAG pins.
The PSD supports JTAG In-System-Configuration
(ISC) commands, but not Boundary Scan. The PS-
Dsoft Express software tool and FlashLINK JTAG
programming cable implement the JTAG In-Sys-
tem-Configuration (ISC) commands. A definition
of these JTAG In-System-Configuration (ISC)
commands and sequences is defined in a supple-
mental document available from ST. This docu-
ment is needed only as a reference for designers
who use a FlashLINK to program their PSD.