Z90251 Datasheet, PDF (65/97 Pages) Zilog, Inc. – eZVision 200 Television Controllers with OSD

Z90255 ROM and Z90251 OTP
32 KB Television Controller with OSD
57
7 Input/Output Ports
There are 20 input/output (I/O) ports. In addition, seven pulse-width modulators
(PWM), PWM1 through PWM6, and PWM11, can be configured as regular output
ports. The maximum number of I/O ports available is 27. Please refer to the port
bank and number carefully for exact addressing and access. See Table 39
through Table 49.
Table 39 Port configuration Register 00h: Bank F (PCON)
Bit
7
6
5
4
3
2
R/W
R/W R/W R/W
Reset
1
1
1
Note: R = Read W = Write X = Indeterminate
R/W
1
R/W
1
R/W
1
1
R/W
1
0
R/W
0
Bit/
Field
Bit
Position R/W Value
Description
Low EMI Z8
7
Oscillator
R/W
0 Low EMI Noise
1 Standard-POR
Low EMI Port 6
6
R/W
0 Low EMI Noise
1 Standard-POR
Low EMI Port 2
5
R/W
0 Low EMI Noise
1 Standard-POR
Reserved
4, 3
R
W
Return 1
Write 1s
Low EMI Port 4 and 2
PWMs
R/W
0 Low EMI Noise
1 Standard-POR
Low EMI OSD
1
Oscillator
R/W
0 Low EMI Noise
1 Standard-POR
Reserved
0
R/W
Return Unknown
No Effect
Ports 2, 4, and 6 can be set for Standard or Low EMI. The Low EMI option
can also be selected for the microcontroller oscillator or OSD oscillator. Standard
(1) is the High setting. Following Power-On Reset, Bits 1, 2, 5, 6, 7 each
has a value of 1.
PS001301-0800