Epson LQ-2550, Technical Manual

Page: 103 / 301

2.3.3.1 LED Drive Section
Each LED is controlled and driven
by expander driver MSM59371, which includes a 16-bit shift
register and LED drivers.
Figure 2-52 shows the data transfer timing for the MSM59371, and Figure 2-53 shows a block diagram
of the 1.
The MSM59371 converts 16-bit serial data (DATA IN) from the sub CPU into parallel data using a
synchronous clock and trigger signal (LOAD), then outputs the data to the output ports (O 1 to O 16).
Output ports 01 to 014 are used to drive the and 015 and 016 are for the signals that control
the reading of the switch states.
DATA IN
016 015 014 013 012 011 09
*1 LED7 LEO LEO lO 4
* ’
LOAD
I n d i c a t e s a n o l d v a l u e .
a n e w v a l u e .
I
Switch read control flag
NOTES: 1. An LED turns on when the data bit is “1”.
2. Refer to Table A-41 for the layout of the
Figure 2-52. Data Transfer Timing
DATA IN
RESET
LOAD
D1 D2 D3 D5 D6 D7 Da D9 D1 1
16-BIT LATCHES WITH RESET
I I I
I I 1
01 02 03 04 05 06 07 08 09 010 011 012 013 014 015” 016
Figure 2-53. Block Diagram
2-56