SAF-C164SM Infineon Technologies, SAF-C164SM Datasheet - Page 263

• Manufacturer Part Number: SAF-C164SM
• Description: 16-Bit CMOS Microcontroller
• Manufacturer: Infineon Technologies

15.2
After sending the identification byte, the BSL enters a loop to receive 32 bytes via ASC0.
These bytes are stored sequentially in locations 00’FA40
internal RAM. Up to 16 instructions may be placed in the RAM area. To execute the
loaded code, the BSL then jumps to location 00’FA40
The bootstrap loading sequence is now terminated, but, the C164CM remains in BSL
mode. Most probably, the initially loaded routine will load additional code or data, as an
average application is likely to require substantially more than 16 instructions. This
second receive loop may use the pre-initialized interface ASC0 directly to receive data
and store it to arbitrary user-defined locations.
This second level of loaded code may be the final application code. It may also be
another, more sophisticated, loader routine that adds a transmission protocol to enhance
the integrity of the loaded code or data. It may also contain a code sequence to change
the system configuration and enable the bus interface to store the received data into
external memory.
This process may go through several iterations or may directly execute the final
application. In all cases, the C164CM will continue to run in BSL mode, with the
watchdog timer disabled and limited access to the internal code memory. All code
fetches from the internal ROM area (00’0000
mapped to segment 1) are redirected to the special Boot-ROM. Data fetches access will
access the internal code memory of the C164CM, if any is available, but will return
undefined data on ROMless devices.
Note: Data fetches from a protected ROM will not be executed.
15.3
In order to execute a program in normal mode (i.e. watchdog timer active, full access to
user memory, etc.), the BSL mode must first be terminated. The C164CM exits BSL
mode in two ways:
• upon a software reset, ignoring the external configuration (P0L.4 or RD)
• upon a hardware reset, not configuring BSL mode.
After the non-BSL reset, the C164CM will start executing out of user memory as
externally configured via PORT0 or RD/ALE (depending on EA).
User’s Manual
Loading the Startup Code
Exiting Bootstrap Loader Mode
15-5
H
… 00’7FFF
H
, i.e. the first loaded instruction.
H
H
or 01’0000
through 00’FA5F
C164CM/C164SM
Bootstrap Loader
H
… 01’7FFF
Derivatives
V1.0, 2002-02
H
of the
H
, if