树莓派ubuntu mate 修改屏幕解析度为800x480

树莓派的启动配置依靠/boot/config.txt来进行配置， 自己的HDMI屏幕是800X480的，其配置参数如下

此配置对使用ubuntu mate和noob来进行安装的raspbian的都可以使用。

1. # uncomment if you get no picture on HDMI for a default "safe" mode
2. #hdmi_safe=1
3. 一定要将此处的hdmi_safe=1注释掉，否则会优先使用此配置
4.  
5. # uncomment this if your display has a black border of unused pixels visible
6. # and your display can output without overscan
7. #disable_overscan=1
8.  
9. # uncomment the following to adjust overscan. Use positive numbers if console
10. # goes off screen, and negative if there is too much border
11. #overscan_left=16
12. #overscan_right=16
13. #overscan_top=16
14. #overscan_bottom=16
15.  
16. # uncomment to force a console size. By default it will be display's size minus
17. # overscan.
18. #framebuffer_width=1280
19. #framebuffer_height=720
20.  
21. # uncomment if hdmi display is not detected and composite is being output
22. hdmi_force_hotplug=1
23.  
24. # uncomment to force a specific HDMI mode (here we are forcing 800x480!)
25. hdmi_group=2
26. hdmi_mode=87
27. hdmi_cvt=800 480 60 6 0 0 0

此处的作用是使用DMT模式来配置HDMI， 并且添加HDMI mode 87其自定义的解析度为800x480刷新频率为60帧

1. max_usb_current=1
3. # uncomment to force a HDMI mode rather than DVI. This can make audio work in
4. # DMT (computer monitor) modes
5. #hdmi_drive=2
6.  
7. # uncomment to increase signal to HDMI, if you have interference, blanking, or
8. # no display
9. #config_hdmi_boost=4
10.  
11. # uncomment for composite PAL
12. #sdtv_mode=2
13.  
14. #uncomment to overclock the arm. 700 MHz is the default.
15. #arm_freq=800