CY545 Stepper System Controller
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When the CY545 is reset, it will read the first three locations of the external memory. If the
values read are 12H, 34H, and 56H respectively, the CY545 will then switch to the program
execution mode, and start reading commands from location 00003 of the memory. This allows
the CY545 to work in a stand alone mode, without any commands from a host computer or
other source than the memory itself. This function is shown below:
00000
00001
00002
00003
12H
34H
56H
...
12H in address 0
34H in address 1
56H in address 2
First CY545 command in address 3
This feature will only occur if the first three bytes have the proper key codes in them. Any other
values in those locations will keep the CY545 in the direct command mode, waiting for
commands from a host system before doing anything.
To set up the auto start function, simply record the data bytes 12h, 34h, and 56h, in locations 0
to 2 of the memory, followed immediately by the command sequence desired. For example:
Y 0<cr>
E<cr>
Set memory pointer address to zero
Following sequence is recorded to memory
<Ctrl-R>4V
R 125<cr>
F 15<cr>
key sequence 12h, 34h, 56h
standard CY545 commands follow now
.......
additional start up commands
Q<cr>
End of memory content definition
When the CY545 is now reset, it will execute the memory-based commands, starting with the
“R125<cr>” command, since the key sequence was found in the first three locations.
As a special convenience, you may command the CY545 to ignore the auto start command
sequence, by holding the XMEM_SEL signal low while the CY545 is reset. If the signal is low,
the CY545 will not test the memory contents for the 12h, 34h, 56h key sequence. Instead, the
CY545 will set itself into the Command mode, and wait for commands from the serial or parallel
interface.
This is especially useful during program development, where errors in the memory content must
be corrected before the CY545 can run the memory based commands. Without this feature, you
would be forced to remove the memory and delete the key sequence, before the CY545 could
be operated with the memory again.
The sequence for bypassing the Auto Start tests is:
•
•
•
•
•
Drive the XMEM_SEL signal low
Reset the CY545
Delay 2 milliseconds after reset is released
Release the XMEM_SEL signal
Issue any CY545 commands in the direct Command mode
© 2002 Cybernetic Micro Systems
45
Chapter 12 - External Memory Support
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