Sabre Smart Devices HDMI RPU

[atillametetured]

Hello,

Regarding the pull-up resistors on the DDC pins, they should be pulled high with weak PU resistors, which is the case for the CEC and HPD on the Sabre for Smart Devices. However I2C lines are not pulled up externally. I assume there are internal resistors on these pins to pull the line high when not operating, which is according to the I2C bus specification. Why then the HPD or CEC lines cannot be pulled high internally? Are there no internal PU on the pins they are conencted (K1 and K2) ? If not, where can I see which pins have internal PU and which dont?

Also the HDMI specification 1.3a states Source SCL and SDA pins should  have minimum 1.5k and maximum 2.0k ohm pull ups while as sink SCL pull up should be 47k ohms and does not mention the SDA line. Is this compliant with IMX6? I am planning to use IMX as the transmitter to stream video on an LCD so I assume I have to comply with the source parameters that are 1.5k-2.0k gap. Is this satisfied with the internal pull ups in IMX?

Regards,

Mete

[igorpadykov · Accepted solution]

Hi Atilla

pads K1,K2 (HDMI_HPD, HDMI_DDCCEC) have not internal pull resistors,

this is described in p.276 Table 4-1. Pin Assignments i.MX6DQ Reference Manual (rev.3  7/2015)

http://cache.freescale.com/files/32bit/doc/ref_manual/IMX6DQRM.pdf

SCL and SDA (EIM_EB2, EIMD16) have internal pull resistors, however not in 1.5k-2.0k range,

so they should be connected externally. Pad properties (pull resistor values, e.t.c.) can

be found in Chapter 26 IOMUX Controller (IOMUXC) in descriptions of IOMUXC_SW_PAD_CTL_PAD_x_y

registers.

Best regards

igor

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[atillametetured]

Hello Igor,

Thank you very much for the information.

Best Regards,

Mete