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1,874 Views
Registered: ‎03-26-2016

External I2C GPIO Expander on FMC Card (zc706)

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Hello,

 

I have been trying to install a new I2C GPIO expander to show as a gpiochip in /sys/class/gpio on the 706 Board.

This GPIO expander (PCA9534A) is part of an FMC card (Inrevium TB-FMCL-MIPI) and runs with VCCO 3V3.

I modified the SCL and SDA pins IOSTANDARD that go to the LPC FMC connector to LVCMOS33.

In the Vivado design, this device is connected to an AXI I2C interface.

 

I modified the device tree to include it as follows:

&amba {
	i2c@40040000 {
		compatible = "xlnx,xps-iic-2.00.a";
		interrupt-parent = <&intc>;
		interrupts = <0 30 4>;
		reg = <0x40040000 0x10000>;
		#address-cells = <1>;
		#size-cells = <0>;
	
		pca9534: gpio@3C {
			compatible = "nxp,pca9534";
			reg = <0x3C>;
			gpio-controller;
			#gpio-cells = <2>;
		};
	};
};

Where 0x3C what I believe is the correct address for the device.

 

During boot up, i receive the following errors:

pca953x 1-003c: failed reading register
pca953x: probe of 1-003c failed with error -5

I have a scope connected to the SDA and SCL pins. Strangely enough they are not pulled up all the way to 3V3 but only at around 2V.

In XSDK I have a small program that attempts to open the device i2c-1 set the address and write something. When I launch it I can see the SCL line going down for an instant.

 

I'm not familiar with any of these components and my knowledge kind of stops here.

I'm using Petalinux 2015.4 and Vivado 2015.4

What am I doing wrong?

 

Thanks!

Dario.

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3,288 Views
Registered: ‎03-26-2016

Re: External I2C GPIO Expander on FMC Card (zc706)

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I was on the wrong I2C line.

It was not so clear from the FMC card documentation.

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3,289 Views
Registered: ‎03-26-2016

Re: External I2C GPIO Expander on FMC Card (zc706)

Jump to solution

I was on the wrong I2C line.

It was not so clear from the FMC card documentation.

0 Kudos