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10.7 Configurable Digital Inputs/Outputs
PiGear Nano also comes with four configurable digital I/O pins.
These four pins can be configured as either inputs or outputs. DIO-1 and DIO-2 are in one group,
while DIO-3 and DIO-4 are in another group. The pins in the same group must be in the same
input/output mode. Therefore, there are four possible configurations:
DIO-1
DIO-2
DIO-3
DIO-4
Configuration 1
INPUT
INPUT
INPUT
INPUT
Configuration 2
INPUT
INPUT
OUTPUT
OUTPUT
Configuration 3
OUTPUT
OUTPUT
INPUT
INPUT
Configuration 4
OUTPUT
OUTPUT
OUTPUT
OUTPUT
When the pin is in OUTPUT mode, it works as open drain output, which can bear up to 12V and drain
up to 500mA current.
The implementation uses two pieces of PCF8574 chips and they are connected to two I2C buses:
I2C-1 and I2C-6. Both chips have the same 0x20 I2C address. The one on I2C-6 works as an
internal controller and the one on I2C-1 provides the 4 DIO channels (mapped to bit 4~7 in I2C
register).
Summary of Contents for PiGear Nano
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