Epson LQ-2550 Technical Manual page 129

2.3.7.1 E05A09BA Gate Array (MCU: 4B)
The MCU has two 4-phase stepper motor phase switching pulse generation circuits that can be
controlled separately. Phase switching timing, motor forward rotation, reverse rotation, and holding,
and the phase switching system are all controlled by the sub CPU. In addition to the above, the MCU
can control three ports.
Refer to Appendix A. 1.1.9 for details of the MCU.
The MCU (4B) goes active when address MMIO 1 is output by the sub CPU. However, the operating mode
is selected by a combination of the low order (4-bit) address and the RD (RCK) or ~ (~) signal. Table -
2-52 shows these combinations.
x
H
H x
L
L L
H
L
H
—
—
L
NOTES: 1.X . . . Don't care.
2. When the printer power is on or when the LOW
LOW.
Table 2-52. MCU (4B) Address Allocations
ADO SCK
x
x x x
L L H
L
H L
H L H
H L
!
H
L H
H
H L
L L H
L
H L
H
L H
H L
L L H
H
H L
L H
H
H
L
L
L H
H
H L
— — —
—
2-83
Function
Changes nothing.
CR motor rotational c-w
direction
2-2
motor phase
CR
switching
1-2
2-2
PF motor phase
switching
1-2
OUT = H
OUT = L
OUT = H
OUT = L
OUT = H
OUT = L
OUT = H
OUT = L
Same as the RST signal input
Not used
Resets the internal circuit and closes
the output gate.
INIT signal is input the RST signal goes
REV.-A
Remark
Left to righ
Carriage
Right to Ief
used
Not
Selects R56.
Selects R57.
Selects R55.
Enables IC (7 D).
--
—.