C509-L_97 Datasheet, PDF (265/290 Pages) Siemens Semiconductor Group – 8-Bit CMOS Microcontroller

Bootstrap Loader
C509-L
10.4.2.4 Selection of Operating Mode 3
Mode 3 is used to execute a custom software in the external FLASH memory at any start address.
The header block, which has to be prepared and sent by the host for the activation of operating
mode 3 has the structure as shown in figure 10-24.
Figure 10-24
Header Block for Operating Mode 3
Mode 3 performs a direct program execution at a given startaddress, which is sent in the header
block. After sending the appropriate header block no further serial communication is necessary for
this mode. The block diagram for the communication between the host and the MCU in mode 3 is
shown in figure 10-25.
Figure 10-25
Operating Mode 3 Communication Structure
Note: The start address startaddress has to be greater than 200H, because in the bootstrap
mode the bootstrap loader overlaps the code address area of the external FLASH memory
from 0000H to 01FFH.
Semiconductor Group
10-27
1997-10-01