Mpu Initialization - Printronix L5020 Maintenance Manual

MPU Initialization

Starting conditions
MPU initialization starts when the printer is turned on.
Description of operations
1. EPRDY (Engine Power Ready) signal assertion
The print engine asserts the EPRDY signal to inform the controller that the
engine is ready for communication. When this signal goes true, the controller
may poll the engine status by sending the "Read Basic Status" command.
If an error occurs, the engine returns basic status information indicating an error,
in response to the "Read Basic Status" command from the controller. When the
controller receives this basic status information, it sends a "Read Error Status"
command to the engine, then displays an error message on the control panel
based on the returned error status information.
When the printer power is turned on, the engine asserts the SYNC signal (raster
synchronization) at fixed intervals, in order to indicate the horizontal scanning
start time for printing.
These fixed intervals are as follows:
1500 µsec for 240 dpi
1200 µsec for 300 dpi
900 µsec for 400 dpi
2. Memory check and memory initialization
3. Timer initialization
4. Control panel initialization
5. Mechanism initialization routine is called
6. RDY (Ready) signal assertion
The RDY signal is asserted by the print engine to inform the controller that the
print engine is ready to receive the *PRNT (print) signal.
2–36 Principles of Operation