HP 750 - Manual (Page 46)

5-4 Functional Overview C4705-90000
ASICs
On the main PCA, the processorĆsupport ASIC is designed to manipulate swath data into the
actualfiring order for the nozzles on the four cartridges that are mounted on the carriage
assembly. The processorĆsupport ASIC receives pixels from the physical swath RAM and
sends them serially to the carriage ASIC.
A main processor on the main PCA controls all plotter operations with the help of the
processorĆsupport ASIC and the servo processor. Communications between the servo
processor and the main processor take place through registers in the processorĆsupport ASIC.
The processorĆsupport ASIC provides pulseĆwidthĆmodulated signals to the YĆaxis
(carriageĆaxis) and the XĆaxis (mediaĆaxis) motor drivers, to drive the YĆaxis and the XĆaxis
motors. The linear encoder connected to the carriage PCA gives the processorĆsupport ASIC
feedback about the position of the carriage. The XĆaxis motor encoder on the XĆaxis motor
gives the processorĆsupport ASIC feedback about the position of the XĆaxis motor.
In addition, the processorĆsupport ASIC contains a DRAM controller that generates
multiplexor controlĆandĆenable strobes for the DRAM row and column addresses during a
memory access. The DRAM controller also arbitrates between a memory request and a
refresh request and performs the refresh operation.
Servo Processor
The servo processor communicates with the main processor through registers in the
processorĆsupport ASIC. The servo processor writes information into the registers and sends
an interrupt to the main processor. The main processor then reads the registers, and the
interrupt is automatically cleared. Using this procedure, the servo processor provides the
main processor with information from the plotter sensors. The sensors give the main
processor the ability to check status conditions.
The servo processor controls the:
D Servo motors.
D Front panel.
D Fan.
D Sensors.
D Electrically erasable readĆonly memory (EEROM).
D Stepper motors.
Stepper Motors
There are three types of stepper motors:
D The primer stepper motor is used to drive the nozzle primer.
D The bailstepper motor drives the bail.
D The wiper stepper motor drives the orthogonalwiper.