树莓派使用hdmi转vga连接显示器自动设置的分辨率有时会不正确，需要手动设置合适的分辨率。
vi /boot/config.txt
hdmi_group=2hdmi_mode=16hdmi_ignore_edid=0xa5000080hdmi_mode根据分辨率的不同，填写的数字也不同，以下是分辨率对应的数字
hdmi_mode=1 640x350 85Hzhdmi_mode=2 640x400 85Hzhdmi_mode=3 720x400 85Hzhdmi_mode=4 640x480 60Hzhdmi_mode=5 640x480 72Hzhdmi_mode=6 640x480 75Hzhdmi_mode=7 640x480 85Hzhdmi_mode=8 800x600 56Hzhdmi_mode=9 800x600 60Hzhdmi_mode=10 800x600 72Hzhdmi_mode=11 800x600 75Hzhdmi_mode=12 800x600 85Hzhdmi_mode=13 800x600 120Hzhdmi_mode=14 848x480 60Hzhdmi_mode=15 1024x768 43Hz DO NOT USEhdmi_mode=16 1024x768 60Hzhdmi_mode=17 1024x768 70Hzhdmi_mode=18 1024x768 75Hzhdmi_mode=19 1024x768 85Hzhdmi_mode=20 1024x768 120Hzhdmi_mode=21 1152x864 75Hzhdmi_mode=22 1280x768 reduced blankinghdmi_mode=23 1280x768 60Hzhdmi_mode=24 1280x768 75Hzhdmi_mode=25 1280x768 85Hzhdmi_mode=26 1280x768 120Hz reduced blankinghdmi_mode=27 1280x800 reduced blankinghdmi_mode=28 1280x800 60Hzhdmi_mode=29 1280x800 75Hzhdmi_mode=30 1280x800 85Hzhdmi_mode=31 1280x800 120Hz reduced blankinghdmi_mode=32 1280x960 60Hzhdmi_mode=33 1280x960 85Hzhdmi_mode=34 1280x960 120Hz reduced blankinghdmi_mode=35 1280x1024 60Hzhdmi_mode=36 1280x1024 75Hzhdmi_mode=37 1280x1024 85Hzhdmi_mode=38 1280x1024 120Hz reduced blankinghdmi_mode=39 1360x768 60Hzhdmi_mode=40 1360x768 120Hz reduced blankinghdmi_mode=41 1400x1050 reduced blankinghdmi_mode=42 1400x1050 60Hzhdmi_mode=43 1400x1050 75Hzhdmi_mode=44 1400x1050 85Hzhdmi_mode=45 1400x1050 120Hz reduced blankinghdmi_mode=46 1440x900 reduced blankinghdmi_mode=47 1440x900 60Hzhdmi_mode=48 1440x900 75Hzhdmi_mode=49 1440x900 85Hzhdmi_mode=50 1440x900 120Hz reduced blankinghdmi_mode=51 1600x1200 60Hzhdmi_mode=52 1600x1200 65Hzhdmi_mode=53 1600x1200 70Hzhdmi_mode=54 1600x1200 75Hzhdmi_mode=55 1600x1200 85Hzhdmi_mode=56 1600x1200 120Hz reduced blankinghdmi_mode=57 1680x1050 reduced blankinghdmi_mode=58 1680x1050 60Hzhdmi_mode=59 1680x1050 75Hzhdmi_mode=60 1680x1050 85Hzhdmi_mode=61 1680x1050 120Hz reduced blankinghdmi_mode=62 1792x1344 60Hzhdmi_mode=63 1792x1344 75Hzhdmi_mode=64 1792x1344 120Hz reduced blankinghdmi_mode=65 1856x1392 60Hzhdmi_mode=66 1856x1392 75Hzhdmi_mode=67 1856x1392 120Hz reduced blankinghdmi_mode=68 1920x1200 reduced blankinghdmi_mode=69 1920x1200 60Hzhdmi_mode=70 1920x1200 75Hzhdmi_mode=71 1920x1200 85Hzhdmi_mode=72 1920x1200 120Hz reduced blankinghdmi_mode=73 1920x1440 60Hzhdmi_mode=74 1920x1440 75Hzhdmi_mode=75 1920x1440 120Hz reduced blankinghdmi_mode=76 2560x1600 reduced blankinghdmi_mode=77 2560x1600 60Hzhdmi_mode=78 2560x1600 75Hzhdmi_mode=79 2560x1600 85Hzhdmi_mode=80 2560x1600 120Hz reduced blankinghdmi_mode=81 1366x768 60Hzhdmi_mode=82 1080p 60Hzhdmi_mode=83 1600x900 reduced blankinghdmi_mode=84 2048x1152 reduced blankinghdmi_mode=85 720p 60Hzhdmi_mode=86 1366x768 reduced blanking参考链接：http://shumeipai.nxez.com/2013/08/31/custom-display-resolution-raspberry-pie.html