Daewoo 20V1NTS, Service Manual

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Fast R, G, B insertion : The external R, G, B insertion needs a fast switching and cannot be controlled by the software
(instruction cycle of 1µ sec). The fast switching pin 16 of SCART is directly connected to the TV processor pin 45 ( Fast
blanking input ). The display is synchronised with the selected video source, i.e. to get stable R, G, B signal insertion they
must be synchronised with the selected video source.
4. µ-Controller I/O pin configuration and function
The I/O pins of the µ-Controller can be configured in many ways. All port functions can be individually programmed by the
controlling software.
Each I/O port pin can be individually programmed in these configurations :
Open drain
In this mode, the port can function as input and output. It requires an external pull-up resistor. The maximum allowable
supply voltage for this pull up resistor is +5V.
So in this mode it is possible to interface a 5 Volt environment like I2C while the µ-Controller has a 3.3 Volt supply.
Push-Pull
The push pull mode can be used for output only. Both sinking and sourcing is active, which leads to steep slopes. The
levels are 0 and Vddp, the supply voltage 3.3Volts.
High impedance
This mode can be used for input only operation of the port.
Special port for LED
Pin 10 and 11 have the same functionality as the general I/O pins but in addition, their current source and sink capacity is
8 mA instead of 4 mA. These pins are used for driving LED's via a series current limiting resistor.
µ-Controller I/O pin configuration and function table
5
FUNCTIONAL DESCRIPTION
APPENDIX
pin name
configuration
description
Stand by TV on
1 n.u. High impedance High impedance not used
2 SCL Open Drain Open Drain Serial clock line
3 SDA Open Drain Open Drain Serial data line
4 SECAM L' High impedance
Push Pull / High SIF filter swi AM/FM
impedance switching
5 OCP High impedance High impedance
Over Current Protection (Switch the set
OFF if the voltage on this pin is <2.3V )
6 RF AGC in High impedance High impedance
Used during ATSS to measure
7RF signal level.
7 Key in High impedance High impedance Local keyboard input
8 S/SW High impedance High impedance external video switch
10 Red LED High impedance Open Drain
11 Green LED Open Drain High impedance
62 Audio mute Push Pull High impedance