Q7-A29
Q7-A29 - Rev. First Edition: 1.0 - Last Edition: 1.0 - Author: S.B. - Reviewed by G.G. Copyright © 2016 SECO S.r.l.
36
3.2.3.10
HDMI interface signals
As told in the previous paragraph, the AMD G-Series SOCs offer two Digital Display Interfaces, configurable to work in HDMI/DVI/DP/eDP modes.
Digital Display Interface #1, in particular, is used to implemented HDMI or Display Port interface.
Signals involved in HDMI management are the following:
T/TMDS_CLK-: TMDS differential Clock.
T/TMDS_TX0-: TMDS differential pair #0.
T/TMDS_TX1-: TMDS differential pair #1.
T/TMDS_TX2-: TMDS differential pair #2.
HDMI_CTRL_DAT: DDC Data line for HDMI panel. Bidirectional signal, electrical level +3.3V_S with a 2k2
Ω
pull-up resistor. Also used as a strap signal for the Q7-
A29 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 2k2
Ω
pull-up resistor.
HDMI_CEC: HDMI Consumer Electronics Control (CEC) Line. Bidirectional signal, electrical level +3.3V_A with a 27k
Ω
pull-up resistor. According to Qseven
®
specifications, the signal is, in 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-A29 dedicated API libraries.
DP_HDMI_HPD#: Hot Plug Detect Input signal. +3.3V_S electrical level signal, active low with 100k
Ω
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 conn voltage level shifters on the carrier board.
Please be aware that the board is factory configured to have HDMI or 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-A29 modules, please take care of specifying if they must have HDMI interface or DP.
