Quanzhi t507 removes the IO expansion chip and retains the expansion pin function

Launched by Feiling embedded OKT507-C As a popular development board, it has rich interface resources , But in fact OKT507-C Of CPU Pin resources are relatively scarce , So how does it implement such rich interface resources ？

The answer is that Feiling uses a IO Expansion chip ——TCA6424A. This is a 24 position I2C And system management bus (SMBus), Input and output (I/O) The extender has an interrupt output 、 Reset and configure registers .

Affected by the current international situation , The situation of the chip industry is very serious , In order to meet the needs of more customers , Keep as many functions as possible while reducing costs , Feiling brings you OKT507-C Get rid of IO The implementation method of retaining the function of the extended pin after expanding the chip .

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On the expansion chip IO Oral quilt WiFi、 bluetooth 、MIPI camera TP2854、DVP Cameras and line-out Port power enable pin reference , If you want to keep these functions , It is necessary to use other pins of the core board that can be reused for these functions .

This article will choose the development board LCD Function pins are reused for these functions , Users can choose according to their actual functional requirements . The method is as follows ：

1. Select pin

The corresponding function pins are shown in the table below ：

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2. Turn off the gpio_ext And the original function of the multiplexing pin

Modify the device tree , take LCD When the function is turned off , This group of pins can be used as ordinary GPIO. The modification path is as follows ：

vi OKT507-linux-sdk/kernel/linux4.9/arch/arm64/boot/dts/sunxi/OKT507-C Common.dtsi

2.1 Turn off the IO Expand chip functions

Because the expansion chip has been removed , So turn off the expansion chip node .

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2.2 Turn off the function of reusing pins

close LCD function , This article chooses LCD The pins on the are used for function multiplexing , The user needs to turn off the pin function used according to the actual situation .

take lcd_used Change it to 0

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lcd0 Node add status = “disabled”;

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3. Change the... Referenced in the device node GPIO

3.1 MIPI-5640 Pin configuration

Path as follows ：

vi OKT507-linux-sdk/kernel/linux-4.9/arch/arm64/boot/dts/sunxi/OKT507-C-Common.dtsi

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3.2 TP2854 Pin configuration

Path as follows ：

vi OKT507-linux-sdk/kernel/linux-4.9/arch/arm64/boot/dts/sunxi/OKT507-C-Common-TP2854M.dtsi

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It should be noted that ,MIPI5640 and TP2854 Share one MIPI Interface , Both functions are used MIPI_PWRDN Pin , Only one function can be selected in actual use , Therefore, this paper selects the same pin in the two function tests .

3.3 DVP-5640 Pin configuration

Path as follows ：

vi OKT507-linux-sdk/kernel/linux-4.9/arch/arm64/boot/dts/sunxi/OKT507-C-Common.dtsi

3.4 WiFi Pin configuration

Path as follows ：

vi OKT507-linux-sdk/kernel/linux-4.9/arch/arm64/boot/dts/sunxi/OKT507-C-Common.dtsi

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3.5 Bluetooth pin configuration

Path as follows ：

vi OKT507-linux-sdk/kernel/linux-4.9/arch/arm64/boot/dts/sunxi/OKT507-C-Common.dtsi

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3.6 Audio pin

Path as follows ：

vi OKT507-linux-sdk/kernel/linux-4.9/arch/arm64/boot/dts/sunxi/OKT507-C-Common.dtsi

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That's all OKT507-C Remove the development board IO The implementation method of retaining the function of the extended pin after expanding the chip , Please refer to the specific test method

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