Chapter 3
Design Considerations for In-Circuit
Programming
This chapter presents signal requirements for in-circuit programming of
the MSP430.
Topic Page
3.1 Signal Connections for In-System Programming and Debugging,
MSP-FET430PIF, MSP-FET430UIF, GANG430, PRGS430
3-2
3.2 External Power 3-4
3.3 Bootstrap Loader 3-5
3-2
3.1 Signal Connections for In-System Programming and Debugging, MSP-
FET430PIF, MSP-FET430UIF, GANG430, PRGS430
With the proper connections, you can use the C-SPY debugger and an
FET hardware JTAG interface such as the MSP-FETP430IF and MSP-
FET430UIF to program and debug code on your own target board. In
addition, the connections will also support the GANG430 or PRGS430
production programmers, thus providing an easy way to program
prototype boards, if desired.
Figure 3-1 shows the connections between the 14-pin FET Interface
module connector and the target device required to support in-system
programming and debugging using C-SPY for 4-wire JTAG
communication. Figure 3-2 shows the connections for 2-wire JTAG mode
(Spy-Bi-Wire). While 4-wire JTAG mode is generally supported on all
MSP430 devices, 2-wire JTAG mode is available on selected devices
only. Refer to Table 2-1 above for information on which interfacing
method can be used on which device.
The connections for the FET Interface module and the GANG430 or
PRGS430 are identical. Both the FET Interface module and GANG430
can supply V
CC
to your target board (via pin 2). In addition, the FET
Interface module and GANG430 have a V
CC
-sense feature that, if used,
requires an alternate connection (pin 4 instead of pin 2). The V
CC
-sense
feature senses the local V
CC
(present on the target board, i.e., a battery
or other local power supply) and adjusts the output signals accordingly. If
the target board is to be powered by a local V
CC
, then the connection to
pin 4 on the JTAG should be made, and not the connection to pin 2. This
utilizes the V
CC
-sense feature and prevents any contention that might
occur if the local on-board V
CC
were connected to the V
CC
supplied from
the FET Interface module or the GANG430. If the V
CC
-sense feature is
not necessary (i.e., the target board is to be powered from the FET
Interface module or the GANG430) the V
CC
connection is made to pin 2
on the JTAG header and no connection is made to pin 4. Figure 3-1 and
Figure 3-2 show a jumper block which supports both scenarios of
supplying V
CC
to the target board. If this flexibility is not required, the
desired V
CC
connections may be hard-wired eliminating the jumper block.
Pins 2 and 4 must not be connected simultaneously.
Note that in 4-Wire JTAG communication mode (Figure 3-1), the
connection of the target RST signal to the JTAG connector is optional
and not required. The MSP430 development tools and device
programmers perform a target reset through issuing a JTAG command to
gain control over the device. However, in the case this should be
unsuccessful, the RST signal of the JTAG connector may be used by the
development tool or device programmer as an additional way to assert a
device reset.