User's Manual l MBa8x UM 0100 l © 2021, TQ-Systems GmbH
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close to the DP socket. A self-resetting fuse of 2 A is provided on the DP_PWR pin (DP spec requires a fuse of max. 3 A).
The connection of HDMI to this port is not provided!
Note: NXP explains in the i.MX8 QM/i.MX8 QXP Hardware Developers Guide
The Display Port silicon IP natively supports the DisplayPort Dual Mode (DP++). There are no current
plans to support this functionality in the BSP or to validate this feature in silicon.
For this reason this functionality is not supported on the MBa8x.
3.14.8.2
HDMI In
The i.MX 8 provides an HDMI input. Thus, for example, image data can be converted to another display interface. HDMI-RX
supports a resolution of up to 4K at 30 FPS. HEC (HDMI Ethernet Channel) is not supported.
The differential HDMI signals are extended and have a differential impedance of 100 Ω. HDMI_RX_MON_5V is connected to pin
18 (+5V) of the HDMI socket by means of 100 nF to ground. This 5 V, which is provided by the HDMI source, also supplies the
pull-ups on the DDC lines. HDMI_RX_CEC (Consumer Electronics Control) is connected to 3.3 V via 27 kΩ and Schottky diode
(pull-up).
ARC (Audio Return Channel): HDMI_RX_ARC_N remains unconnected. The shield of the HDMI socket is connected to GND.
3.14.8.3
LVDS
The i.MX 8 has two LVDS controllers, each with a dual LVDS interface or two channels. Each of the channels uses four differential
lanes for transmission.
The mainboard allows a single LVDS or dual LVDS to be connected at a time. For this reason, 2x GPIO (BLT_EN, RESET#), one
PWR_EN and one PWM signal are provided per LVDS interface. The GPIOs are multiplexed on the CPU instead of the dedicated
I2C signals. The LVDSx_PWM and LVDSx_PWR_EN signals are already dedicated pins of the LVDS bus.
TQMa8x
LVDSx (CH0/CH1)
LVDS data
5 V / 12 V
USB
LVDS control
5 V / 3,3 V
RESET , BLT _EN,
PWR_EN,
CONTRAST/PWM
2x
Figure 14:
Block diagram LVDS
The differential LVDS signals are extended and have a differential impedance of 100 Ω. Furthermore, all signal lines are provided
with ESD protection.
As with all TQ mainboards, there is no redriver and no ground lines between the differential pairs. Experience has shown that this
limits the possible cable length to approx. 30 cm.
3.14.8.4
MIPI DSI
The TQMa8x has two MIPI DSI interfaces with four differential lanes each. In addition, the interface offers an I2C master for each
of the two DSI ports as well as a dedicated GPIO and PWM pin.
These interfaces are intended for the connection of an adapter board for embedded display modules. This allows easy
accessibility and flexibility in the choice of display, but requires the use of an adapter board.