C509-L_97 Datasheet, PDF (257/290 Pages) Siemens Semiconductor Group – 8-Bit CMOS Microcontroller

Bootstrap Loader
C509-L
10.4.2.1 Selection of Operating Mode 0
Operating mode 0 is used to transfer a program from the host to the XRAM of the MCU via serial
interface. The header block, which has to be prepared and sent by the host for the activation of
operating mode 0 must have the structure as shown in figure 10-11.
Figure 10-14
Header Block for Operating Mode 0
The operating mode 0 header block transfers the 16-bit XRAM startaddress for the following data
blocks, the number of data bytes in the following data or EOT blocks (blocklength), and a
checksum byte.
After confirming the received header block, the bootstrap loader enters mode 0, in which the desired
data is transmitted from the host to the XRAM of the MCU using the two transfer blocks of the types
DATA and EOT, which are shown in figure 10-11.
The complete communication for mode 0 (including entering mode 0) between the host and the
MCU after the synchronization shows the block diagram in figure 10-15.
If an error occurs while transmitting data blocks, the host software has to react on error codes, sent
by the bootstrap loader when rejecting a block. This case is illustrated in the block diagram of
figure 10-16.
Semiconductor Group
10-19
1997-10-01