Seco Qseven Q7-974 User Manual page 37

3.2.3.10 HDMI interface signals
As told in the previous paragraph, the Intel
Digital Display Interface #0, in particular, is used to implemented HDMI or Multimode Display Port interface.
Please be aware that the board is factory configured to have HDMI or Multimode Display Port interface.
If the board purchased is in HDMI configuration, then voltage level shifters on the carrier board are not necessary (they can also interfere with
regular working of the board). When placing an order of Q7-974 module, please take care of specifying if it must have HDMI interface or DP.
Signals involved in HDMI management are the following:
TMDS_CLK+/TMDS_CLK-: TMDS differential Clock.
TMDS_TX0+/TMDS_TX0-: TMDS differential pair #0
TMDS_TX1+/TMDS_TX1-: TMDS differential pair #1
TMDS_TX2+/TMDS_TX2-: TMDS differential pair #2
HDMI_CTRL_DAT: DDC Data line for HDMI panel. Bidirectional signal, electrical level +3.3V_S with a 2k2Ω pull-up resistor. Also used as a strap signal for the Q7-
974 module (please check par. 3.2.4 for further details).
HDMI_CTRL_CLK: DDC Clock line for HDMI panel. Bidirectional signal, electrical level +3.3V_S with a 2k2Ω pull-up resistor.
HDMI_CEC: HDMI Consumer Electronics Control (CEC) Line. Bidirectional signal, electrical level +3.3V_S. According to Qseven
reality, a General Purpose 1_wire bus interface, that can be used for implementation of HDMI_CEC. Real usage of this signal depends on Q7-974 dedicated API
libraries.
HDMI_HPD#: Hot Plug Detect Input signal. +3.3V_S electrical level signal, active low with 100kΩ pull-up resistor. Please consider that HDMI specification assume
that the Hot Plug signal is active high, and at +5V_S level. An inverting voltage level shifter is therefore needed on the Carrier board to ensure the working of HDMI
port
Please be aware that it is not necessary to implement voltage level shifter for TMDS differential pairs on the Carrier board, but such level shifters are still necessary
on Control data/Clock signals, as well as for Hot Plug Detect signal.
Voltage clamping diodes are also highly recommended on all signal lines for ESD suppression.
Please refer to the following schematics as an example of implementation of HDMI connection + voltage level shifters on the carrier board.
Q7-974
Q7-974 User Manual - Rev. First Edition: 0.1 - Last Edition: 2.3 - Author: S.B. - Reviewed by G.G. Copyright © 2017 SECO S.r.l.
®
Atom E38xx family of SOCs offer two Digital Display Interfaces, configurable to work in HDMI/DVI/DP++/eDP modes.
® specifications, the signal is, in
37