13 Error Handling
56
KRONOS 20
13.4
Bootloader
The HEINZMANN Digital Controls include what is called a bootloader. This programme
section is stored at a specific location of the read-only memory (ROM) and is programmed
once for all at the factory. The bootloader cannot be cleared except by means of special
devices.
On starting the control programme by powering it up or by a reset, the bootloader pro-
gramme is always executed first. This programme performs various relevant tests telling
whether the actual control programme is or is not operable. Based on these tests the boot-
loader decides whether further programme execution can be handed on to the control pro-
gramme or whether execution must remain confined to the bootloader to preclude any risk
of personal injury or damage to the engine.
As long as the programme is in bootloader mode, KRONOS 20 cannot start to
work. The entire bootloader tests and the subsequent initialization of the main
programme will take about 300 ms..
13.4.1
Bootloader-Start Tests
The following section describes which tests are performed by the bootloader and which
measures may have to be taken. As long as these test are being conducted, there will be
no communication with the device, especially when due to some fatal error the pro-
gramme is caught in an infinite loop. For this reason, the current test mode is indicated
using the error output. The output is toggled to get an indication about the current test.
Watchdog-Test
This is to check whether the watchdog integrated into the processor is operable. This
is to ensure that in case of an undefined programme execution the control will go into
a safe state after a pre-defined time. If the outcome of the watchdog test is negative,
the bootloader programme will remain in an endless loop, and the above indications
will not change.
Bootloader Programme-Test
The error output signal will be reset. By this test, a check-sum is calculated over the
memory area containing the bootloader programme and compared with the check-
sum pre-programmed at the factory. If the sums do not match, the bootloader pro-
gramme will remain in an endless loop, and the above indications will be maintained.
RAM-Test Boot Loader Programme
During this test, various binary patterns are written to the RAM used by boot loader
and read out again. If at least one storage location does not contain the expected
code, the bootloader programme enters into an endless loop, and the above indica-
tions are maintained.
Note
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