C509-L_97 Datasheet, PDF (251/290 Pages) Siemens Semiconductor Group – 8-Bit CMOS Microcontroller

Bootstrap Loader
C509-L
10.4 Phase III: Serial Communication with the Host
After the successful synchronization with the host the bootstrap loader enters phase III, in which it
communicates with the host to select the desired operating modes. This communication between
host and bootstrap loader in phase III is based on different types of transfer blocks. Prior to the
description of the phase III operations, the transfer blocks are described in the next section.
10.4.1 Block Transfer Protocol
The communication between the host and the bootstrap loader is done by a simple transfer
protocol, which is based on a specified block structure. The communication is nearly unidirectional,
that means, that the host is sending several transfer blocks and the bootstrap loader is just
confirming them by sending back single acknowledge or error bytes. The MCU itself does not send
any transfer blocks. Figure 10-9 shows the general format of the transfer block.
Format Item
blocktype
data area
checksum
Description
This byte determines how data in the data area field
has to be interpreted.
The implemented blocktypes are:
00H Type: “HEADER”
01H Type: “DATA”
02H Type: “END OF TRANSMISSION” (EOT)"
This area contains a number of bytes which represent
the data of the transfer block. The number of bytes in
the data area may range between 00H and 7CH.
For safety purposes a checksum is build over
blocktype and data area field and sent after the data
area.
Figure 10-9
Basic Structure of a Bootstrap Loader Transfer Block
Semiconductor Group
10-13
1997-10-01