Z90251 ZILOG [Zilog, Inc.], Z90251 Datasheet - Page 75

• Manufacturer Part Number: Z90251
• Description: eZVision 200 Television Controllers with OSD
• Manufacturer: ZILOG [Zilog, Inc.]

Bit 6 resets the IR Capture Timer. To stop the timer, set this bit to 1. To start the
timer, set the bit to 0.
Bits 5 and 4 set the IR Capture Edge. The rising edge, the falling edge, or both
edges of an input signal can be used as the source of IR interrupts. If both edges
are set as interrupt sources, Timer Control Register 0 (TCR0: 01h: Bank C)
must be read and checked by the Interrupt Service Routine (ISR) in order to
identify which edge was captured.
Bits 3 and 2 contain a time constant used in a digital filter to process the IR
Capture module in order to prevent errors.
Bits 1 and 0 set the IR Capture Counter to one of four different speeds.
The IR capture counter is driven by the clock generated by dividing the system
clock in the Z90255.
Table 52 IR Capture Register 0 03h: Bank C (IR_CP0)
Bit/
Field
CAP Glitch
CAP Speed
Bit
R/W
Reset
Note: R = Read W = Write X = Indeterminate
Bit/
Field
IR Capture Register 0
Bit
Position
3, 2
1, 0
R
7
0
Bit
Position
7,6,5,4,3,2,1,0
R
6
0
R/W
R/W
R/W
R
5
0
32 KB Television Controller with OSD
Value
R/W
00
01
10
00
01
10
11
11
R
4
0
R
Description
Glitch Filter Disabled
<2SCLK Filtered Out
<8SCLK Filtered Out
<16SCLK Filtered Out
SCLK/32
SCLK/4
SCLK/8
SCLK/16
Value Description
R
3
0
Reading Low Byte of IR
Capture Data
R
2
0
PS001301-0800
R
1
0
R
0
0
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