Can I set HDMI resolution to 320x240? I have this 50 $ projector and I connect a Dongle to it with HDMI cable-- so I have actual screen of 320x240, but the screen is broadcast at 720p. This results in unreadable letters, even if I set font size to huge setting. Can I somehow change the resolution dongle works?
Hope this helps. 
On my Note3 running Lollipop I was able to check for supported external resolutions by running ( via a terminal app or adb shell )

&gt;dmesg


and ( filtering with grep ) looking for the lines:

&lt;6&gt;[  581.051746] hdmi_edid_add_sink_video_format: EDID: format: 1 [640x480 p60 4/3], Supported
&lt;6&gt;[  581.051756] hdmi_edid_add_sink_video_format: EDID: format: 1 [640x480 p60 4/3], Supported by MHL
&lt;6&gt;[  581.051767] hdmi_edid_add_sink_video_format: EDID: format: 16 [1920x1080 p60 16/9], Supported
&lt;6&gt;[  581.051777] hdmi_edid_add_sink_video_format: EDID: format: 16 [1920x1080 p60 16/9], Not-Supported by MHL
&lt;6&gt;[  581.051790] hdmi_edid_add_sink_video_format: EDID: format: 4 [1280x 720 p60 16/9], Supported
&lt;6&gt;[  581.051801] hdmi_edid_add_sink_video_format: EDID: format: 4 [1280x 720 p60 16/9], Supported by MHL
&lt;6&gt;[  581.051812] hdmi_edid_add_sink_video_format: EDID: format: 133 [1280x1024 p60 5/4], Not-Supported
&lt;6&gt;[  581.051822] hdmi_edid_add_sink_video_format: EDID: format: 133 [1280x1024 p60 5/4], Not-Supported by MHL
&lt;6&gt;[  581.051833] hdmi_edid_add_sink_video_format: EDID: format: 132 [1024x768 p60 4/3], Not-Supported
&lt;6&gt;[  581.051843] hdmi_edid_add_sink_video_format: EDID: format: 132 [1024x768 p60 4/3], Not-Supported by MHL


which you'll note correspond to supported resolutions in:

&gt;cat /sys/devices/virtual/graphics/fb1/edid_modes 
1,4


then select your preferred output using :

&gt;setprop hw.hdmi.resolution 1


and then re-plug the mhl adapter.

which in my case resulted in 640x480 which was the only option supported by my 800x600 projector.

Thanks to this Force 720p Resolution on InForce 6540