Sony UP-21MD Service Manual page 73

* Screen dispiay controi
A screen display control signal is generated by IC102. Exclusive clock circuit uses in this IC102. The
clock frequency have an effect to horizontal size on the screen. The H-sync and V-sync signal inputs
from the VPR-74 board are required as a timing pulse during operation. The control signal of display
data is output from CPU (pins 1 to 3 of IC103). Characters are actually superimposed using an analog
switch on the VPR-74 board. No screen display may appear when [SOURCE:THRU] or
[DISPLAY:OFF] is set in the menu.
« Remote 1 input and infrared remote control reception
An infrared remote control pulse is received using the infrared photosensor (IC302) on the KEY-49
board. This pulse is waveform-shaped by IC209 on the SY-299 board and output to the IF-852 board.
When a wired remote control is connected to J1 on the IF-852 board, a wired remote control pulse is
selected as output. When it is not connected to J1, output pulse of a photosensor is selected as output.
One of selected pulse is waveform-shaped by IC209 on the SY-299 board and shift by IC106, then input
to CPU (pins 40 and 41 of IC103). Therefore, the wire remote control operation may fail due to the
failure of J1 on the IF-852 board.
* Remote 2 input
The two types of remote controls can be connected that are a open/short remote control (RM-91 etc.) and
analog-level remote control (FS-36 etc.) in J2 on the IF-852 board. A open/short-level signal is processed
by 1C205 and input to CPU (pin 75 of IC103). An analog-level signal is processed by IC206 and input to
CPU (pin 49 of IC103).
¢ Remote 2 output
The control signal of a BUSY output signal is. output by CPU (pin 34 of IC103) and driven using a buffer
(1C208). Afterward, a signal is input to two circuits of TTL output and open collector output, then an
output signal is decided either them by setting of S201 on the SY-299 board.
4-4-4. Communication with Internal CPU in Unit
« Interface with mechanical control block on the SY-299 board (IC302: PRT)
Bi-directional communication is performed by the asynchronous serial communication that uses serial
communication interface CH.0 incorporated into CPU.
Signal line name vo Description
SY_PRT_TXD Output Communication data (IC103: SY — 1C302: PRT)
PRT_SY_RXD Input Communication data (IC302: PRT > 1C103: SY)
SY_PRT_RTS Output Communication enable (IC103: SY — 1C302: PRT) L:active
PRT_SY_CTS Input Communication enable (IC302: PRT — IC 103: SY) Liactive
Communication format
System Asynchronous system
Data length 8 bits
Stop bit 1 bit
Parity None
Baud rate 19200 bps
UP-2iMD V1 4-35