3.5 inch 320x480 IPS Capacitive Touch Screen LCD Module SPI Serial ST7796U Driver for Arduino R3/Mega2560

This is for the 4" 320x480 capacitive touch display with ST7796s.I first tested out the display itself, and found the TFT_eSPI to work well. For reading the touchscreen, I only really tested position and haven't looked into gestures yet, but I found that both RAK14014-FT6336U and the Arduino-FT6336U libraries worked equally well for what I tested. The RAK library actually used up a bit more program memory, about 240 bytes more, so if your processor is small in that department, might consider that.Here are some tidbits that I needed to learn through experimentation that might help others get running quicker:1) SPI interface to the display runs well at 80MHz. I used ESP32 DEV, so no problem.2) On ESP32, use default SPI pins in order to use hardware driver, which is fastest.3) On I2C interface for touchpad, use default pins for SDA and SCLK. Easiest way to check which pins these are is to print out SDA and SCLK to the serial port.4) The FT6336U interrupt pin is mostly useful to wake up the processor while in a sleep state. During normal operation, interrupts constantly come in and cannot easily be used to determine when a touch has happened. Need to poll the TD_STATUS register to see if non-zero and not use the interrupt line in normal operation.5) TFT_eSPI is a very inclusive library, but you will need to alter it unless you have a board and pin setup combo that matches one of the many examples. This is not documented well. I recommend taking the SetupX_Template.h file in the User_Setups folder, configure it according to the comments in the file, save it as a new filename, and then you only need to change a single line in the standard library files from that point onwards, even if this library gets updated in the future. Then you can either copy this custom name file to the User_Setup.h file and overwrite the original. Or, everytime a new library version comes out, just edit the User_Setup_Select.h file to comment out the User_Setup.h and add a line to use the new file you created. Both ways work well. But expect that you will need to do this bit of customization to the library.6) I2C address for the touchpad is as in the FT6336U library, address 0x38. You can also find example scanner sketches online which will confirm your board's touchpad I2C address.Overall, the display is a great value - nice and bright, large, and with a capacitive touchscreen that pretty much works out of the box without calibration.

This 4.0-inch display is a fantastic option, especially if you're looking for something larger than the usual 2.5" to 3.5" screens. The 320x480 resolution provides sharp visuals, and the capacitive touch (FT6336U) is highly responsive and accurate with no calibration needed.Key Highlights:✅ 4-wire SPI for the ST7796 display and I2C for the FT6336U capacitive touch—a great setup that ensures fast refresh rates and smooth performance.✅ Use TFT-eSPI library support for video, though some customization is needed.✅ FT6336U library for touch, which works flawlessly.✅ 14-line ribbon connector with labeled pins—a fantastic inclusion! My dev board had all the display pins lined up but not the touch, so I had to use the ribbon to connect the touch functionality while still mounting the display. The fact that they included the ribbon cable is a huge plus.✅ SD card slot (though I haven't tested it).If you're looking for the best 4-wire SPI screen with great refresh rates, this is the one to get. Highly recommended for anyone needing a solid display.Comes with documentation (better than most), but is still confusing. Just follow the advice of the reviews.4.5 stars (rounded up to 5). Not perfect, but I haven't seen any better SPI displays.

Update: Changed from 5 to 4. The first review was just on the LCD display - I had not tested the Touch. The Touch init() tries to read 3 registers - which my unit failed to do (all data return was zero). I sent several emails to customer support and never got a reply (Note: 2 days earlier I sent an email about where to acquire technical info and they replied the next day). I guess customer service is good for directing you to a web site but NOT about any technical questions.I returned the unit to Amazon and requested a replacement - which I received in 3 days. Attempted the Touch init() again - this time the device returned 2 of the 3 requested register values. With partial response, I tested Touch for actually detecting and responding with Touch coordinates - It worked as it should - So I'm keeping the display.Below is the website for any technical information on the unit - so you don't have to request it yourself. Also .. the Touch communicates over I2C - the device addresses are (8 bit address) - write 0x70 and read - 0x71. The I2C addresses published in libraries for the touch device are incorrect for this product.Web Site: http://www.lcdwiki.com/4.0inch_Capacitive_SPI_Module_ST7796Hope that helps!!First Review: ....I don't use any libraries - I write my own drivers. Several users stated that they tried the ST7796s driver associated with the display library they were using and it did not work - so they tried a different driver chip.Most all these driver chips are very close in nature - if not exactly alike. I suspect many of the libraries have not fully implemented the ST7796s yet show it in their driver selection - leading to people having issues.I used the Initialization sequence found in 'Adafruit_ST7796S_kbv.cpp'. Hardware setup for 4 wire SPI with hardware Display Reset. Display works as expected. If you are having issues - use (if you have one) a logic analyzer to capture the control signals and compare them to what is stated in the specification.For the size and capacitive touch - I think the price is very good.