Can Jetson AGX Orin SPI1/SPI2/SPI3 Be Used with a Fintek F75113 SPI GPIO Expander?

Robotics & Edge Computing Jetson Systems Jetson AGX Orin
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We plan to connect a Fintek F75113 GPIO controller to one of the SPI interfaces on Jetson AGX Orin.

The F75113 supports SPI and will be used to provide 8 GPOs and 8 GPIs. According to the F75113 datasheet, its SPI interface consists of SPI_CLK, SPI_CS#, SPI_MOSI and SPI_MISO, and the F75113 operates as an SPI target device. Therefore, we plan to configure the Jetson AGX Orin SPI controller as the SPI initiator.

Could you please help confirm the following:

  1. Can SPI1, SPI2 and SPI3 on Jetson AGX Orin be used as general-purpose SPI initiators to communicate with external SPI target devices such as the Fintek F75113?

  2. Are there any restrictions on the type of SPI target device that can be connected to SPI1/SPI2/SPI3?

  3. Are there any specific limitations or requirements regarding SPI mode, clock frequency, chip-select timing, pinmux configuration, or software support?

  4. Since the F75113 operates at 3.3 V, could you also confirm the I/O voltage levels of SPI1, SPI2 and SPI3 on the AGX Orin module, and whether an external level shifter is required?

The F75113 datasheet is attached for reference.

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F75113_V0.17P.pdf (1.1 MB)

The attached file is the datasheet. Can this device be connected to any of the SPI interfaces on the Jetson AGX Orin?

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hello nirvanasssssss,

assuming you are using JetPack 7.2.1 / Jetson Linux r39.2.1

yes, SPI1, SPI2, and SPI3 on Jetson AGX Orin can be configured as general-purpose SPI initiators. in this configuration, CLK, MOSI, and chip select are outputs from Jetson, while MISO is an input. SPI1 and SPI3 provide two chip-select signals, while SPI2 provides one.
there is no restriction specific to an SPI GPIO expander. compatibility depends on the target device’s protocol, electrical levels, SPI mode, and timing requirements.

Jetson AGX Orin supports SPI modes 0 through 3. the module datasheet specifies a maximum SCK frequency of 81.6 MHz, but the configured frequency and chip-select timing must also satisfy the F75113 requirements.
for example, its datasheet specifies setup/hold requirements and a minimum chip-select deselect time of 100 ns.
the selected pins must be configured for their SPI functions through pinmux, and the corresponding SPI controller must be enabled in the device tree. a suitable Linux SPI client driver or a configured userspace SPI interface is also required.

regarding voltage levels, the SPI1/SPI2/SPI3 pins on the AGX Orin module use 1.8V CMOS signaling and are 3.3V tolerant as inputs. however, 3.3V tolerance does not mean that a 1.8V Jetson output is guaranteed to be recognized by a 3.3V target. in this case, the attached F75113 datasheet specifies a minimum input-high voltage of 2.0 V for SPI_CLK, SPI_CS#, and SPI_MOSI. therefore, Jetson’s 1.8 V outputs do not meet the F75113 input-high requirement, and level translation is required for those signals.
the F75113 SPI_MISO output is within the Jetson input tolerance, but power sequencing and possible back-driving should also be considered. using an appropriately rated, direction-aware SPI level translator for all four signals is recommended. please also select a level translator that supports the required SPI clock frequency and push-pull signaling.