CY545 Stepper System Controller
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You should be aware of this time period delay when using EEPROM, because it is possible to
send serial characters to the CY545 faster than the EEPROM can accept them, when running
the serial interface at higher baud rates. It is best to have a time delay between each character
in this case, or else use the CTS signal to hold off the communications until the CY545 is ready.
Note that the parallel interface takes care of this time delay on its own, since the CY545 will stay
busy while it is writing the character to the memory.
Additional care must be taken when using the parallel command interface along with external
memory. Since both functions share the CY545 data bus, the parallel command source must be
able to release the data bus when the CY545 is commanded to access the external memory.
The host system should only drive the data lines when the CY545 is not busy, and the host
must stay off the bus while the CY545 is executing commands from the memory. No special
signals are provided in this mode; the CY545 simply reads commands from the memory and
executes them until it encounters a stop command.
Special HP LED Display Control Signals
Along with the normal serial and parallel data outputs, the CY545 also supports a special
parallel LED display, using the Hewlett-Packard HDSP-211x displays. These are compact, 8-
character displays, with programmable intensity, custom characters, and other features. The
displays are very convenient and compact, making them useful in a minimal CY545 based
system.
© 2002 Cybernetic Micro Systems
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Chapter 16 - Timing and Control
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