I bought this so that my power consumption for a solar/battery shack is cut by 60% (to about 5W) from that of using a full sized screen (around 12W). More importantly for radio, it also gets rid of the very RFI-noisy large monitor, restoring peace to the HF bands. The extra space freed-up by the diminutive screen is also very welcome.
The screen is a 1024 x 600 WaveShare 7" (17.8cm) LCD, which I bought for £60 from ModMyPi. It has a HDMI input, and touchscreen capability.
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| Success, but it took me a while to get there! The very high display quality is not really evident in this photo. |
The screen comes complete, but you have to assemble the plastic enclosure, which is machined to a very high standard. Fitting the whole thing together is quite fiddly, but simple. You can save a fair bit of money if you buy the screen without a frame. For radio purposes, the lack of plastic frame often makes mounting the screen easier.
There are no instructions with the screen, which is strange, because it doesn't need a lot of instructions; just a few lines are enough.
Instead, you have to visit a Wiki page for the device. This is fine, but a little 'Chinglish' in its delivery.
What is not clear, until you spend hours playing around with the Raspberry Pi's config.txt file, is that the configuration changes simply need to be added at the end of the config.txt file. You don't edit those values already in the file, which is how I thought it worked. I think the maker and/or the seller should stick a simple few lines of advice on this in the box. But margins are so low they don't bother.
For posterity, and to help those struggling as I did, what you have to do is:
(1) Connect your Pi to a normal-sized HDMI screen such as a TV, PC monitor, or recycled laptop screen (the latter idea, with a suitable screen driver from ebay, is a good, though more cumbersome (and non-touchcreen) alternative to the Waveshare, and a little cheaper, that also does not need any of these config file modifications)
(2) Boot up your Pi. With normal-sized screens, it detects the correct display setttings without user input. The Raspberry Pi 4B may settle down into correct screen display without these settings, but it might prove unstable; you are much better to change the settings as given.
(3) Click on the command dialog box
(4) Type in sudo nano /boot/config.txt (note, there must be a space between 'nano' and /boot).
(5) Immediately below the last command that is already in the config.txt file, (i.e. do not insert spaces or blank lines, but immediately below), enter the lines below accurately:
max_usb_current=1
hdmi_group=2
hdmi_mode=87
hdmi_cvt 1024 600 60 6 0 0 0
hdmi_drive=1
There must be no spaces before or after the '=' sign, and the numbers in the hdmi_cvt line have a space between the 'cvt' and 1024, and then spaces between each number (i.e. hdmi_cvt<space>1024<space>600<space>60<space>6<space>0<space>0<space>0)
If you use the LCD with Raspberry Pi 4 B, you need to remove the line
dtoverlay=vc4-fkms-V3D from config.txt file
(6) Press CTRL X and press 'Y' for yes to save.
(7) type sudo reboot and press <return> It may be better to disconnect the Pi from the large display and reconnect it to the Waveshare before pressing <return> 'blind' (without a screen to see proceedings).
(2019 December 23 - REMINDER TO ME: Audio input and output in the WSJT-X software settings should be sysdefault:codec; also on new Pi installs, make sure audio input/output is USB Codec).
One reason for making the instructions clearer is that if you get it wrong, you will have to go and edit the config file on another computer (if you can access the config file, which isn't always the case). If you can't see it on a PC, for example, the fastest turnaround is to quick-format the SD card again on a PC and reinstall the NOOBS files, then insert into the Pi for it to reinstall its OS, then go to the top of the instructions above at number (1).
Once I understood and wrote these lines into the config file, the screen immediately went from being a mess of flashing lines to a full-colour, vibrant display. Power from a USB 'powerbank' is enough to keep both the Pi and the screen running for several hours, making backpacking a reality.
Other people have commented that this screen has a high quality display, and indeed it does! Instead of a low resolution display like you get with so many other models, this is just like using a full-sized monitor in miniature. It isn't a struggle to read the screen at all.
The screen has attachments for the Pi itself on the back, which then effectively gives you a Pi-based tablet, or a small laptop, with the considerable advantage of being modifiable for many practical projects.
One piece of advice for Raspberry Pi 4B applications: the screen comes with a micro-HDMI male to female adapter, which is very bulky and doesn't make for a very robust connection. I strongly advise you to buy a micro-HDMI male to full size HDMI male cable, which is far more secure and much less heavy on the Pi's HDMI board socket.
A great product, provided it stands the test of time! UPDATE: I've been using this screen for 4 years now, and it's seen some tough action: left in my /A site for months, which is cold and damp, and also a lot of roughing it in my car with /P seaside operations. This is a good product!
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