C161RI_1 Datasheet, PDF (224/317 Pages) Siemens Semiconductor Group – 16-Bit CMOS Single-Chip Microcontroller

The Bootstrap Loader
C161RI
15 The Bootstrap Loader
The built-in bootstrap loader of the C161RI provides a mechanism to load the startup program,
which is executed after reset, via the serial interface. In this case no external memory or an internal
ROM/OTP/Flash is required for the initialization code starting at location 00’0000_H.
The bootstrap loader moves code/data into the internal RAM, but it is also possible to transfer data
via the serial interface into an external RAM using a second level loader routine. ROM memory
(internal or external) is not necessary. However, it may be used to provide lookup tables or may
provide “core-code”, i.e. a set of general purpose subroutines, e.g. for IO operations, number
crunching, system initialization, etc.
RSTIN
P0L.4
RxD0
TxD0
1)
2)
4)
3)
5)
CSP:IP
6)
Int. Boot ROM BSL-routine
32 bytes
user software
1) _{BSL initialization time, > 2 µs @ fCPU = 20 MHz.}
2) _{Zero byte (1 start bit, eight ‘0’ data bits, 1 stop bit), sent by host.}
3) _{Identification byte, sent by C161RI.}
4) _{32 bytes of code / data, sent by host.}
5) _{Caution: TxD0 is only driven a certain time after reception of the zero byte (2.5 µs @ fCPU = 20 MHz).}
6) _{Internal Boot ROM.}
Figure 15-1
Bootstrap Loader Sequence
The Bootstrap Loader may be used to load the complete application software into ROMless
systems, it may load temporary software into complete systems for testing or calibration, it may also
be used to load a programming routine for Flash devices.
The BSL mechanism may be used for standard system startup as well as only for special occasions
like system maintenance (firmware update) or end-of-line programming or testing.
Semiconductor Group
15-1
1998-05-01