3.5 tft lcd hdmi free sample
Compatible and Direct-connect with any revision of Raspberry Pi. (If you are using a Raspberry Pi Zero / Zero 2 W, an additional HDMI cable is required.)
The 3.5 inch LCD Display is directly pluggable into a Raspberry Pi and perfectly fits various Pi models from B+ to Raspberry Pi 3B+. It is a brilliant alternative for an HDMI monitor. When set up, it behaves as a human-machine interface enabling the user to prototype with the Raspberry Pi device anywhere at any time.
In these videos, the SPI (GPIO) bus is referred to being the bottleneck. SPI based displays update over a serial data bus, transmitting one bit per clock cycle on the bus. A 320x240x16bpp display hence requires a SPI bus clock rate of 73.728MHz to achieve a full 60fps refresh frequency. Not many SPI LCD controllers can communicate this fast in practice, but are constrained to e.g. a 16-50MHz SPI bus clock speed, capping the maximum update rate significantly. Can we do anything about this?
The fbcp-ili9341 project started out as a display driver for the Adafruit 2.8" 320x240 TFT w/ Touch screen for Raspberry Pi display that utilizes the ILI9341 controller. On that display, fbcp-ili9341 can achieve a 60fps update rate, depending on the content that is being displayed. Check out these videos for examples of the driver in action:
This driver does not utilize the notro/fbtft framebuffer driver, so that needs to be disabled if active. That is, if your /boot/config.txt file has lines that look something like dtoverlay=pitft28r, ..., dtoverlay=waveshare32b, ... or dtoverlay=flexfb, ..., those should be removed.
If you have been running existing fbcp driver, make sure to remove that e.g. via a sudo pkill fbcp first (while running in SSH prompt or connected to a HDMI display), these two cannot run at the same time. If /etc/rc.local or /etc/init.d contains an entry to start up fbcp at boot, that directive should be deleted.
-DPIRATE_AUDIO_ST7789_HAT=ON: If specified, targets a Pirate Audio 240x240, 1.3inch IPS LCD display HAT for Raspberry Pi with ST7789 display controller
-DKEDEI_V63_MPI3501=ON: If specified, targets a KeDei 3.5 inch SPI TFTLCD 480*320 16bit/18bit version 6.3 2018/4/9 display with MPI3501 display controller.
-DGPIO_TFT_DATA_CONTROL=number: Specifies/overrides which GPIO pin to use for the Data/Control (DC) line on the 4-wire SPI communication. This pin number is specified in BCM pin numbers. If you have a 3-wire SPI display that does not have a Data/Control line, set this value to -1, i.e. -DGPIO_TFT_DATA_CONTROL=-1 to tell fbcp-ili9341 to target 3-wire ("9-bit") SPI communication.
-DGPIO_TFT_RESET_PIN=number: Specifies/overrides which GPIO pin to use for the display Reset line. This pin number is specified in BCM pin numbers. If omitted, it is assumed that the display does not have a Reset pin, and is always on.
-DGPIO_TFT_BACKLIGHT=number: Specifies/overrides which GPIO pin to use for the display backlight line. This pin number is specified in BCM pin numbers. If omitted, it is assumed that the display does not have a GPIO-controlled backlight pin, and is always on. If setting this, also see the #define BACKLIGHT_CONTROL option in config.h.
Here is a full example of what to type to build and run, if you have the Adafruit 2.8" 320x240 TFT w/ Touch screen for Raspberry Pi with ILI9341 controller:
If the size of the default HDMI output /dev/fb0 framebuffer differs from the resolution of the display, the source video size will by default be rescaled to fit to the size of the SPI display. fbcp-ili9341 will manage setting up this rescaling if needed, and it will be done by the GPU, so performance should not be impacted too much. However if the resolutions do not match, small text will probably appear illegible. The resizing will be done in aspect ratio preserving manner, so if the aspect ratios do not match, either horizontal or vertical black borders will appear on the display. If you do not use the HDMI output at all, it is probably best to configure the HDMI output to match the SPI display size so that rescaling will not be needed. This can be done by setting the following lines in /boot/config.txt:
These lines hint native applications about the default display mode, and let them render to the native resolution of the TFT display. This can however prevent the use of the HDMI connector, if the HDMI connected display does not support such a small resolution. As a compromise, if both HDMI and SPI displays want to be used at the same time, some other compatible resolution such as 640x480 can be used. See Raspberry Pi HDMI documentation for the available options to do this.
Interestingly, fbcp-ili9341 is about ~33msecs faster than a cheap 3.5" KeDei HDMI display. I do not know if this is a result of the KeDei HDMI display specifically introducing extra latency, or if all HDMI displays connected to the Pi would have similar latency overhead. An interesting question is also how SPI would compare with DPI connected displays on the Pi.
To get tearing free updates, you should use a DPI display, or a good quality HDMI display. Beware that cheap small 3.5" HDMI displays such as KeDei do also tear - that is, even if they are controlled via HDMI, they don"t actually seem to implement VSYNC timed internal operation.
Having no vsync is not all bad though, since with the lack of vsync, SPI displays have the opportunity to obtain smoother animation on content that is not updating at 60Hz. It is possible that content on the SPI display will stutter even less than what DPI or HDMI displays on the Pi can currently provide (although I have not been able to test this in detail, except for the KeDei case above).
The main option that affects smoothness of display updates is the #define USE_GPU_VSYNC line in config.h. If this is enabled, then the internal Pi GPU HDMI vsync clock is used to drive frames onto the display. The Pi GPU clock runs at a fixed rate that is independent of the content. This rate can be discovered by running tvservice -s on the Pi console, and is usually 59Hz or 60Hz. If your application renders at this rate, animation will look smooth, but if not, there will be stuttering. For example playing a PAL NES game that updates at 50Hz with HDMI clock set at 60Hz will cause bad microstuttering in video output if #define USE_GPU_VSYNC is enabled.
If USE_GPU_VSYNC is disabled, then a busy spinning GPU frame snapshotting thread is used to drive the updates. This will produce smoother animation in content that does not maintain a fixed 60Hz rate. Especially in OpenTyrian, a game that renders at a fixed 36fps and has slowly scrolling scenery, the stuttering caused by USE_GPU_VSYNC is particularly visible. Running on Pi 3B without USE_GPU_VSYNC enabled produces visually smoother looking scrolling on an Adafruit 2.8" ILI9341 PiTFT set to update at 119Hz, compared to enabling USE_GPU_VSYNC on the same setup. Without USE_GPU_VSYNC, the dedicated frame polling loop thread "finds" the 36Hz update rate of the game, and then pushes pixels to the display at this exact rate. This works nicely since SPI displays disregard vsync - the result is that frames are pushed out to the SPI display immediately as they become available, instead of pulling them at a fixed 60Hz rate like HDMI does.
By default fbcp-ili9341 builds with a statistics overlay enabled. See the video fbcp-ili9341 ported to ILI9486 WaveShare 3.5" (B) SpotPear 320x480 SPI display to find details on what each field means. Build with CMake option -DSTATISTICS=0 to disable displaying the statistics. You can also try building with CMake option -DSTATISTICS=2 to show a more detailed frame delivery timings histogram view, see screenshot and video above.
Enable the option #define DISPLAY_ROTATE_180_DEGREES in config.h. This should rotate the SPI display to show up the other way around, while keeping the HDMI connected display orientation unchanged. Another option is to utilize a /boot/config.txt option display_rotate=2, which rotates both the SPI output and the HDMI output.
If fbcp-ili9341 does not support your display controller, you will have to write support for it. fbcp-ili9341 does not have a "generic SPI TFT driver routine" that might work across multiple devices, but needs specific code for each. If you have the spec sheet available, you can ask for advice, but please do not request to add support to a display controller "blind", that is not possible.
Perhaps. This is a more recent experimental feature that may not be as stable, and there are some limitations, but 3-wire ("9-bit") SPI display support is now available. If you have a 3-wire SPI display, i.e. one that does not have a Data/Control (DC) GPIO pin to connect, configure it via CMake with directive -DGPIO_TFT_DATA_CONTROL=-1 to tell fbcp-ili9341 that it should be driving the display with 3-wire protocol.
Yes, fbcp-ili9341 shows the output of the HDMI display on the SPI screen, and both can be attached at the same time. A HDMI display does not have to be connected however, although fbcp-ili9341 operation will still be affected by whatever HDMI display mode is configured. Check out tvservice -s on the command line to check what the current DispmanX HDMI output mode is.
At the moment fbcp-ili9341 has been developed to only display the contents of the main DispmanX GPU framebuffer over to the SPI display. That is, the SPI display will show the same picture as the HDMI output does. There is no technical restriction that requires this though, so if you know C/C++ well, it should be a manageable project to turn fbcp-ili9341 to operate as an offscreen display library to show a completely separate (non-GPU-accelerated) image than what the main HDMI display outputs. For example you could have two different outputs, e.g. a HUD overlay, a dashboard for network statistics, weather, temps, etc. showing on the SPI while having the main Raspberry Pi desktop on the HDMI.
This suggests that the power line or the backlight line might not be properly connected. Or if the backlight connects to a GPIO pin on the Pi (and not a voltage pin), then it may be that the pin is not in correct state for the backlight to turn on. Most of the LCD TFT displays I have immediately light up their backlight when they receive power. The Tontec one has a backlight GPIO pin that boots up high but must be pulled low to activate the backlight. OLED displays on the other hand seem to stay all black even after they do get power, while waiting for their initialization to be performed, so for OLEDs it may be normal for nothing to show up on the screen immediately after boot.
If the backlight connects to a GPIO pin, you may need to define -DGPIO_TFT_BACKLIGHT=
fbcp-ili9341 needs a few megabytes of GPU memory to function if DMA transfers are enabled. The gpu_mem boot config option dictates how much of the Pi"s memory area is allocated to the GPU. By default this is 64MB, which has been observed to not leave enough memory for fbcp-ili9341 if HDMI is run at 1080p. If this error happens, try increasing GPU memory to e.g. 128MB by adding a line gpu_mem=128 in /boot/config.txt.
All the ILI9341 displays work nice and super fast at ~70-80MHz. My WaveShare 3.5" 320x480 ILI9486 display runs really slow compared to its pixel resolution, ~32MHz only. See fbcp-ili9341 ported to ILI9486 WaveShare 3.5" (B) SpotPear 320x480 SPI display for a video of this display in action. Adafruit"s 320x480 3.5" HX8357D PiTFTs is ~64% faster in comparison.
The ILI9486L controller based maithoga display runs a bit faster than ILI9486 WaveShare, 50MHz versus 31.88MHz, i.e. +56.8% bandwidth increase. However fps-wise maithoga reaches only 13.56 vs WaveShare 12.97 fps, because the bandwidth advantage is fully lost in pixel format differences: ILI9486L requires transmitting 24 bits per each pixel (R6G6B6 mode), whereas ILI9486 supports 16 bits per pixel R5G6B5 mode. This is reflected in the above chart refresh rate for the maithoga display (marked with a star).
The Tontec MZ61581 controller based 320x480 3.5" display on the other hand can be driven insanely fast at up to 140MHz! These seem to be quite hard to come by though and they are expensive. Tontec seems to have gone out of business and for example the domain itontec.com from which the supplied instructions sheet asks to download original drivers from is no longer registered. I was able to find one from eBay for testing.
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Ms.Josey 
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