What limits Beagle Board Black HDMI resolution

People, read your docs… According to the latest System Reference Manual, BBB added support for 1920x1080@24Hz resolution: https://github.com/CircuitCo/BeagleBone-Black/tree/master/BBB_SRM.pdf

6.10 HDMI Interface

The BeagleBone Black has an onboard HDMI framer that converts the LCD signals and audio signals to drive a HDMI monitor. The design uses an NXP TDA19988 HDMI Framer.

The following sections provide more detail into the design of this interface.

6.10.1 Supported Resolutions

The maximum resolution supported by the BeagleBone Black is 1280x1024 @ 60Hz. Table 9 below shows the supported resolutions. Not all resolutions may work on all monitors, but these have been tested and shown to work on at least one monitor. EDID is supported on the BeagleBone Black. Based on the EDID reading from the connected monitor, the highest compatible resolution is selected.

Table 9. HDMI Supported Monitor Resolutions


NOTE: The updated software image used on the Rev A5B board added support for 1920x1080@24HZ.

Per above, it seemed that 1920x1080 was possible in the 50-60Hz range without audio. Has the community been able to figure out a way to get that to work?

1920x1080@24HZ is the best it can do.


Great, now how does one specify a particular resolution and audio option upon startup?

I’d like to refine my question to you Gerald…

How can I get 24-bit color with the BBB via either HDMI or LCD (assuming the LCD I wire up is a 24/32-bit color panel)? I thought the TI spec indicated the BBB could drive true-color but all I can manage to get out of the BBB is 16-bit color regardless if I use HDMI or the LCD from 4D Systems.

All 24 bits are available on the expansion headers. I cannot speak for 4D systems as to how their board is designed and if they support 24b mode or not.

HDMI only has 16 bits connected, so you cannot get 24b color on it.


Thanks Gerald,

I will have to confirm this by wiring up another LCD panel to the expansion headers. It’s unfortunate to learn that there is a 16-bit color limitation via HDMI output. On the Raspberry Pi I can issue the “fbset -depth 24” bash command and the HDMI output switches to 24-bit color depth. When I try that command on the BBB it returns with the error “ioctl FBIOPUT_VSCREENINFO: Invalid argument”. Only 8 and 16 work as valid bit depths with the BBB.

We did this for a reason. Our focus was expansion and due to the pin muxing, the extra 8 bits would wipe out a lot of functionality. Se we decided to make those easily accessible when connected to a monitor.


Higher color output through the HDMI connector uses up pins?

Yes. There are a certain amount of pins on the expansion headers. Each pin has up to 8 functions per pin. For each pin that is set to the HDMI function, the other 7 functions are no longer available to the expansion header when the HDMI is in use. Some of these functions are some of the more popular functions. So, we went 16bit so those other function could be there for people to use and still have HDMI capabilities.


Yes, looking at the board schematic, in order to use LCD_DATA16 - 23 (missing 8 bits) you would have to give up 6 GPIO’s and 2 PWM’s.