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3.3 Bootstrap Loader
Bootstrap Loader
When a target socket module is powered from an external supply, the external supply powers the device
on the target socket module and any user circuitry connected to the target socket module, and the FET
interface module continues to be powered from the PC via the parallel port. If the externally supplied
voltage differs from that of the FET interface module, the target socket module must be modified so that
the externally supplied voltage is routed to the FET interface module (so that it may adjust its output
voltage levels accordingly). See the target socket module schematics in
Appendix B .
The JTAG pins provide access to the Flash memory of the MSP430Fxxx devices. On some devices, these
pins are shared with the device port pins, and this sharing of pins can complicate a design (or it may
simply not be possible to do so). As an alternative to using the JTAG pins, most MSP430Fxxx devices
contain a program (a "Bootstrap Loader") that permits the Flash memory to be erased and programmed
simply, using a reduced set of signals. Application reports
SLAA089 and SLAA096 fully describe this
interface. TI does not produce a BSL tool. However, customers can easily develop their own BSL tools
using the information in the application reports, or BSL tools can be purchased from third parties. See the
MSP430 web site for the application reports and a list of MSP430 third-party tool developers.
TI suggests that MSP430Fxxx customers design their circuits with the BSL in mind (i.e., TI suggests
providing access to these signals via, for example, a header).
See FAQ Hardware #11 for a second alternative to sharing the JTAG and port pins.
The BSL tool requires the following device signals:
•
RST/NMI
•
TEST
(1)
or TCK
•
GND
•
VCC
•
P1.1
•
P2.2 or P1.0
(2)
(1)
If present on device
(2)
'1xx and '2xx devices use pins P1.1 and P2.2 for the BSL. '4xx devices use pins P1.0 and P1.1 for
the BSL.
SLAU138F – June 2004 – Revised March 2007 Design Considerations for In-Circuit Programming 27
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