
Description of Units
Hardware-Manual • Doc.-No.: I.2306.21 / Rev. 3.5
CPCI-405
Page 22 of 57
3.3 Function of Coding Switch
3.3.1 Overview
Coding switch
bit
Function
Default setting at delivery
1
no special function / general purpose
OFF
2
no special function / general purpose
OFF
3
no special function / general purpose
OFF
4
switching the boot Flash-EPROM
boot from Flash-EPROM U600
Table 3.3.1: Assignment of coding switch bits
The state of the DIP switches can be read at address 0xF040 0002. Each switch’s state is represented
in the least significant bits.
3.3.2 Switching the Boot-Flash-EPROM via Coding Switch Bit 4
The local operating system is booted from the Flash-EPROM U600 per default (chip select CS0 of
PowerPC 405GP). By means of the coding switch the chip select signal can be switched so that the
Flash-EPROM U610 will be accessed.
This switching can be used, for instance, to boot an ‘Emergency Operating System’ in the second Flash
EPROM, if the board does not boot up again after a change in the default Flash-EPROM.
Position of coding
switch bit 4
Function
0
Memory area of Flash-EPROM U610 is at CS0
1
Memory area of Flash-EPROM U600 is at CS0
(default setting)
Table 3.3.2: Meaning of coding switch bits 4