Epson SQ-B50/2550 Technical Manual page 112

REV.-A
2.4.2.2 Carriage Motor Control
A block diagram of the carriage motor control circuit is shown in Figure 2-47.
(Refer also to Location 14-16/F-1 of the Seima Board Circuit Diagram in the Appendix).
Carriage motor control is not performed directly by the CPU. Rather, the DCU(4B) controls the motor
based on the signals it receives from the CPU (MMIO control).
The DCU is enabled by a LOW MMI002 signal from the MMU.
The CPU sends motor control commands and revolution speed data to the DCU; this allows the motor
speed to be controlled as desired. The DCU, meanwhile, detects position data and stop signals from
the encoder and the carriage home position sensor, and provides this information to the CPU.
The encoder signal is also used as a basis for generating the print timing signal, which is output to the
printhead control circuit. The functions of the carriage motor control circuit can be broadly divided into
the following:
• Speed (revolution speed) control
• Drive current control
• Carriage position control (revolution counter, home position recognition, stop signal output)
• Print timing signal (PTS) generation
DCU (4B)
, - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 1
I
Command Data
.. 00"'07
Spee d Contro ler
ENC
CR Motor
Motor
Drive
Circuit
Motor
Pre-driver
PTS
AOrvA2
..
Reset Signal .. IRST
I
I
_ _
~M..:...M~I..:.0..:.0..:.2
__ I -
.. I CE
I
_.. I=-N_T_'=---
i
STO PSi g n a I
L _
MMIO Address
Printhead Control
Circuit
CHP Sensor
(C RH)
Figure 2-47. Block Diagram of Carriage Motor Control Circuit
2-44