Z90251 Datasheet, PDF (16/97 Pages) Zilog, Inc. – eZVision 200 Television Controllers with OSD

Z90255 ROM and Z90251 OTP
32 KB Television Controller with OSD
8
Table 2 Single-Purpose Pin Descriptions (Continued)
Acronym
V_BLANK
Pin Name(s)
Video Blank
V_CC
V_SYNC
XTAL1, XTAL2
Power Supply
Vertical Sync
Time-Based
Input
Output
Description
CMOS output, programmable polarity. This pin is used as
a super-impose control port to display characters from
video RAM. The signal controls Y-signal output of CRTs
and turns off the incoming video display while the
characters in video RAM are super-imposed on the
screen. The output ports of color data directly drive three
electron guns on the CRT; at the same time VBLANK
output turns off the Y signal.
Power supply
Input pin for external vertical synchronization signal.
These pins connect to the internal parallel-resonant clock
crystal oscillator circuit with two capacitors to GND.
XTAL1 can be used as an external clock input.
1.3 Multiplexed Pin Descriptions
Table 3 lists the Multiplexed Pin acronyms, pin names, and descriptions.
Table 3 Multiplexed Pin Descriptions
Acronym
P20/HLFTN
P24/SCLK0
P25/SDATA0
P26/SCLK1
P27/SDATA1
P62/ADC0
P60/ADC3
Pin Name(s)
Description
Port 2 bit 0 or Halftone Output Port 2 bit 0 can be programmed as an input or output
line.
Port 2 bit 4 or I²C Clock
Port 2 bit 4 or I²C Clock
Port 2 bit 5 or I²C Data
Port 2 bit 5 or I²C Data
Port 2 bit 6 or I²C Clock
Port 2 bit 7 or I²C Data
Port 2 bit 6 or I²C Clock
Port 2 bit 7 or I²C Data
Port 6 bit 2 or
Analog-to-Digital Converter
Channel 0
P62 can be read directly. A negative edge event is
latched into IRQ2 to initiate an IRQ2-vectored interrupt if
appropriately enabled.
Port 6 bit 0 or
Analog-to-Digital Converter
Channel 3
Port 6 bit 0 can be programmed as an input or output
line.
PS001301-0800