Advantech ARK-5420 Series, Руководство пользователя

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ARK-5420 User Manual 56
If one GPIO Pin is set to Output, you can read input value from the bit that register 1
corresponds to.
Register 2 - Polarity Inversion register
This register allows the user to invert the polarity of the Input Port register data. If a
bit in this register is set (written with ‘1’), the corresponding Input Port data is inverted.
If a bit in this register is cleared (written with a ‘0’), the Input Port data polarity is
retained.
If one GPIO Pin is set to Input, you can control the polarity of input pin from the bit
that register 2 corresponds to.
Register 3 - Configuration register
This register configures the directions of the I/O pins. If a bit in this register is set, the
corresponding port pin is enabled as an input with high-impedance output driver. If a
bit in this register is cleared, the corresponding port pin is enabled as an output. At
reset, the I/Os are configured as inputs with a weak pull-up to VDD.
Register 3 is used to set each GPIO as Input or Output:
If the bit is ‘0’, the corresponding GPIO pin is set as Output; If the bit is ‘1’, the corre-
sponding GPIO pin is set as Input.
Table 6.5: Register 2 - Polarity Inversion Register Bit Description
Bit Symbol Access Value Description
7 N7 R/W 0* inverts polarity of Input Port register data
6 N6 R/W 0* 0 = Input Port register data retained (default value)
5 N5 R/W 0* 1 = Input Port register data inverted
4 N4 R/W 0*
3 N3 R/W 0*
2 N2 R/W 0*
1 N1 R/W 0*
0 N2 R/W 0*
Table 6.6: Register 3 - Configuration Register Bit Description
Bit Symbol Access Value Description
7 C7 R/W 1* configures the directions of the I/O pins
6 C6 R/W 1* 0 = corresponding port pin enabled as an output
5 C5 R/W 1* 1 = corresponding port pin configured as input
4 C4 R/W 1*
3 C3 R/W 1*
2 C2 R/W 1*
1 C1 R/W 1*
1 C0 R/W 1*