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Joined: Thu Oct 22, 2015 4:07 pm

DPI + I2C signal conflict

Thu Oct 22, 2015 4:28 pm


I am using a RPi2 Rev 1.1 and I would like to utilize the DPI interface from the GPIO port to run a basic parallel interface tft lcd module.
The module also includes a touchpanel that uses I2C communication.
It appears that there is a signal conflict between the clock signals for the display, i.e. pclk, hsync, vsync, & den, and both i2c interfaces.
Is it possible to re-map the i2c interface to unused gpio, such as GPIO 26 & 27, through device tree manipulation?
I've managed to change the i2c0_pins to <0x1A 0x1B>, but was unsuccessful in probing my i2c device.
I have attached the DPI color data map for reference. I intend on using configuration number 5. Please note that GPIO 0, 1, 2, & 3 are reserved for the display clock signals.

Any help would be much appreciated.

Thank you,
Steffen S.
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Raspberry Pi Engineer & Forum Moderator
Raspberry Pi Engineer & Forum Moderator
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Re: DPI + I2C signal conflict

Thu Oct 22, 2015 7:57 pm

Simply, no. That is why all the official blog/forum posts have stated the fact.

There are only certain pins that the I2C buses can be routed to. For I2C-0, those are 0&1, 28&29, and 44&45. For I2C-1 they are 2&3, 44&45.
GPIOs 28&29 are routed to the camera and display connectors. GPIOs 44&45 are not available on the standard Pi (45 is used for the right audio channel, 44 isn't brought out. They are available on the Compute Module).
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