General-Purpose Input And Output (Gpio); Overview; Operation - Analog Devices MAX96752 User Manual

General-Purpose Input and Output (GPIO)

Overview

This section explains the GPIO function of MFP pins. The GPIO blocks communicate and regenerate state changes
of GPIO pins from one side of the serial link to the other. An input GPIO value on one side of the GMSL link may be
sent to any of the GPIO outputs on the opposite side of the link.
Depending on the pin, they can be used as either full or partial general-purpose input and output (GPIO) pins or for
other functionality (e.g., I C, LOCK, ERRB, etc.). Refer to the data sheets for additional details on GPIO capabilities
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and default states after power-up.
The MAX96752 family has 15 multifunction pins (MFPs), refer to datasheet for full details.

Operation

GPIO pin mapping is coordinated across the serial link through GPIO "pin ID" assignments. Each GPIO input is
assigned a pin ID that is included in the packet sent across the serial link and corresponds with a GPIO output. By
default, the GPIO mapping is GPIO0 to GPIO0, GPIO1 to GPIO1, GPIO2 to GPIO2, etc. The GPIO mappings can be
changed through registers.
GMSL devices use 5-bit pin IDs that can support mapping up to 32 GPIO pins. Note that the usable number of GPIOs
is limited by the specific GPIO pinout. Each GPIO is controlled by three registers: GPIO_A, GPIO_B, and GPIO_C. In
the register documentation, the GPIO mapping is sequential (i.e., the first three GPIO registers correspond to
GPIO0, then the next three to GPIO1, etc.). Additional details related to these registers can be found in the "GPIO
Registers" section of the respective data sheet.
When programming GPIOs, it is important to program the GPIO Rx before the GPIO Tx to avoid asynchronous initial
states. For example, if Tx is low but Rx is high, the first transition of Tx from low to high is ignored by Rx as Rx is
already high. All subsequent transitions are correctly observed.
MFP0
RX_ID = 3
(GPIO0)
GMSL LINK
SERIALIZER DESERIALIZER
MFP3
TX_ID = 3
(GPIO3)
Figure 23. GPIO Forwarding Example with a Transition from MFP3 to MFP0
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