CMS32L051 User Manual |Chapter 2 Pin Function
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2.3.7 Port output mode register (POMxx)
This is the register that sets the output mode in bits. When communicating serially with external devices
with different potentials and simple
I2C
communication with external devices with different potentials, an N-
channel open-drain output mode can be selected for the SDA xx pin.
After the reset signal is generated, the values of these registers become 00H.
Register address = base address + offset address; the base address of the POM register is 0x40040000,
and the offset address is shown in the figure below.
Note: For the bit set to N-channel open-drain output mode (POMmn=1), no internal pull-up resistor is connected.
Figure 2-7 Format of port output mode register
Selection of output mode for the Pmn pin (m=0~3, 5~7, 12~14, n=0~7).
Note: 1 The initial value must be set for the unassigned bits.
2. It is limited to CMS32L051xx-S series products. For products other than the CMS32L051xx-S series, ports P60, P61
are dedicated N-channel open drain output ports and do not need to be configured with POM registers.
3. Ports P121~P124 do not have N-channel open-drain output function.
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