Epson EPL-N1200, Service Manual

Page: 82 / 149

2.2.1.7 Video Interface
The ASIC E05B17 (IC16) maps the SRAM into a different memory space from system memory.
The CPU transmits data from the V-RAM (in the system RAM) to the SRAM using the ASIC
E05B17. The ASIC cell converts the image data in the SRAM from parallel to serial, synchronizes
it, and then transmits it to the engine controller board. In other words, the SRAM is a temporary
buffer used to transmit the image data to the engine controller board.
This serial image data
creates VIDEO signal of video interface.
The signal line of the internal video interface circuit (the C205 MAIN board and engine controller
board) can be broadly divided into four groups. The first group (PRINT, CPRDY, EPRDY, and
PRDY) gives the status of either the video controller or engine controller and indicates whether they
are ready to communicate with each other or ready to start the printing operation.
The second group (VSYNC, HSYNC) is the synchronizing signal for the printing operation. The
third group (VIDEO) is the serial video data signal. The fourth group (CMD, SRCLK, CTBSY, and
ETBSY) is used to transfer the commands (from the video controller) or status (from the engine
controller) for printer mechanism control. Except for VIDEO, PRINT, VSINC, and HSYNC, all
signals are controlled by ASIC E05A93.
This printer has BiRITech function standard. These functions modify the VIDEO signal with the
ASIC E05B17 (IC16).
EPL-N1200 Service Manual Operating Principles
Rev. A 2-23