This feature is not included in precompiled binaries.
To use it you must compile your build. Add the following to user_config_override.h:

The display driver is able to display predefined setups of text or user defined text. To display text using DisplayText set DisplayMode to 0, or set DisplayMode to 1 for the HT16K33 dot-matrix display.

The DisplayText command is used to display text as well as graphics and graphs on LCD, OLED and e-Paper displays (EPD). The command argument is a string that is printed on the display at the current position. The string can be prefixed by embedded control commands enclosed in brackets [].

In order to use the DisplayText command the DisplayMode must be set to 0 (or optional 1 on LCD displays) or other modes must be disabled before compilation with #undef USE_DISPLAY_MODES1TO5.

In the list below p stands for parameter and may be a number from 1 to n digits. On monochrome graphic displays things are drawn into a local frame buffer and sent to the display either via the d command or automatically at the end of the command.

lp = sets a character line to print at (on LCD display p = {0…}, on TFT display p = {1…})
cp = sets a character column to print at (on LCD display p = {0…}, on TFT display p = {1…})
xp = sets the x position for consecutive prints
yp = sets the y position for consecutive prints

Text is printed at the last provided position, either l or y for the vertical position, and either x or x for the horizontal position. Neither x nor y are advanced/updated after printing text.

hp = draws a horizontal line with length p (x is advanced)
vp = draws a vertical line with length p (y is advanced)
Lp:p = draws a line top:p (x,y are advanced)
kp = draws a circle with radius p
Kp = draws a filled circle with radius p
rp:p = draws a rectangle with p with and p height
Rp:p = draws a filled rectangle with p with and p height
up:p:p = draws a rounded rectangle with p with, p height and p radius (not for ILI9341)
Up:p:p = draws a filled rounded rectangle with p with, p height and p radius (not for ILI9341)

z = clear the display
i = (re)init the display (in e-Paper mode with partial update)
I = (re)init the display (in e-Paper mode with full update)
d = update the display
Dp = switch display auto updates on(p=1)/off(p=0), when off display must be updated with d
o = switch display off
O = switch display on
ap = p (0..3) set rotation angle
t = display Tasmota time in HH:MM
tS = display Tasmota time in HH:MM:SS
T = display Tasmota date in DD.MM.YY
pp = pad text with spaces, positive values align left, negative values align right
sp = set text scaling for classic GFX font (scaling factor 1...N)
fp = set font (1=12, 2=24,(opt 3=8)) if font==0 the classic GFX font is used, if font==7 RA8876 internal font is used
Cp = set foreground color (0,1) for black or white and RGB decimal code for color
Bp = set background color (0,1) for black or white and RGB decimal code for color
Cip = set foreground index color (0..18) for color displays (see index color table below)
Bip = set background index color (0..18) for color displays (see index color table below)
wp = draws an analog watch with radius p (#define USE_AWATCH)
Pfilename: = display an rgb 16-bit color image when SD card file system is present

(#define USE_TOUCH_BUTTONS)

Draw up to 16 GFX buttons to switch real Tasmota devices such as relays.

• Button number + 256 - a virtual touch toggle button is created (MQTT => TBT)
• Button number + 512 - a virtual touch push button is created (MQTT => PBT)

Parameters are separated by colons. For example: b0:260:260:100:50:2:11:4:2:Rel 1:

bp p = button number 0-15
xp = x position
yp = y position
xa = x size
ys = y size
oc = outline index color
fc = fill index color
tc = text index color
ts = text size
text: = button text (must end with a colon :) (max 9 chars)

(#define USE_GRAPH and #define NUM_GRAPHS 4 - maximum of 16)

Up to 4 line charts may be defined.

Ticks may be defined by adding tick numbers to the n parameter.
    For example: n = graph number (0..3) + x ticks (16*number of x ticks) + y ticks (1024*number of y ticks).

Parameters are separated by colons.

Gn:xp:yp:xs:ys:t:fmax:fmin = defines a line chart.
n = number up to 4 charts (0..3) + optional ticks
xp = x position
yp = y position
xs = x size (if xs<0) graph is not reinitialized on second call (e.g., restart of scripter)
ys = y size
t = time in minutes for total chart
ymin = float chart minimum y
ymax = float chart maximum y
icol = line color index (only for color graphs)

gn:v Adds a value to the chart buffer
n = number up to 4 charts (0..3)
v = float value to add

Gdn:m = set graph n draw mode 0 = off, 1 = on. When on, redraw graph
Gsn:path: = save graph n to path (if optional SD card is present)
Grn:path: = restore graph n from path (if optional SD card is present)

Selected with Ci and Bi in the ILI9488, SSD1351, and RA8876 color panels

E-Paper displays have 2 operating modes: full update and partial update. While full update delivers a clean and sharp picture, it has the disadvantage of taking several seconds for the screen update and shows severe flickering during update. Partial update is quite fast (300 ms) with no flickering but there is the possibility that erased content is still slightly visible. It is therefore useful to perform a full update in regular intervals (e.g., each hour) to fully refresh the display.

Compilation directives: #define USE_SPI, #define USE_DISPLAY, #define USE_DISPLAY_EPAPER29, or #define USE_DISPLAY_EPAPER42

Remark: the 4.2 e-Paper display requires about 15k of RAM. Therefore it only works with Core 2.42 and above.

The typical specifications for the lifetime of an OLED when permanently on is about 10000 hours (416 days). Dimming to 50% expands the lifetime to about 25000 hours.

The data sheets of the TFT and OLED displays mention burn-in effects when a static display is shown for extended periods of time. You may want to consider turning on the display on demand only.

The EPD font contains 95 characters starting from code 32, while the classic GFX font contains 256 characters ranging from 0 to 255. Custom characters above 127 can be displayed. To display these characters, you must specify an escape sequence (standard octal escapes do not work). The ~character followed by a hex byte can define any character code.

GFXFont:

EPDFont:

I²C displays are connected in the usual manner and defined via the GPIO component selection.

The I²C address must be specified using DisplayAddress XX, e.g., 60. The model must be spedified with DisplayModel, e.g., 2 for SSD1306. To permanently turn the display on set DisplayDimmer 100. Display rotation can be permanently set using DisplayRotate X (x = 0..3).

E-Paper displays are connected via software 3-wire SPI (CS, SCLK, MOSI). The other three interface lines of the display (DC, Reset, busy) may be left unconnected. The jumper on the circuit board of the display must be set to 3-wire SPI.

The ILI9488 and SSD1351 are connected via hardware 3-wire SPI (MOSI=GPIO13, SCLK=GPIO14,CS=GPIO15). The ILI9488 must also be connected to the backlight pin (dimmer supported on SSD1351)

The RA8876 is connected via standard hardware 4-wire SPI (MOSI=GPIO13, MISO=GPIO12, SCLK=GPIO14, CS=GPIO15). No backlight pin is needed (dimmer supported).

Print Text at size 1 on line 1, column 1:
DisplayText [s1l1c1]Hello how are you?

Draw a rectangle and draw text inside with size 2 and 7 chars padded with spaces:
DisplayText [x85y95h130v30h-130v-30s2p7x90y100]37.25 C

Refresh screen:
DisplayText [z]

Draw rectangle from x,y with width and height:
DisplayText [x50y50r200:100]

(line breaks and indentation added to the rules for readability)

Use Tasmota rules to display sensor values, time, and a separation line. Refresh the display every 60 minutes:

rule1 on tele-SHT3X-0x44#Temperature do DisplayText [f1p7x0y5]%value% C endon
      on tele-SHT3X-0x44#Humidity do DisplayText [f1p10x70y5]%value% %[x0y20h296x250y5t] endon
      on tele-BMP280#Pressure do DisplayText [f1p10x140y5]%value% hPa endon
      on Time#Minute|60 do DisplayText [Tt] endon

Show 4 analog channels:

rule1 on tele-ADS1115#A0 do DisplayText [s1p21c1l01]Analog1: %value% adc endon
      on tele-ADS1115#A1 do DisplayText [s1p21c1l3]Analog2: %value% adc endon
      on tele-ADS1115#A2 do DisplayText [s1p21c1l5]Analog3: %value% adc endon
      on tele-ADS1115#A3 do DisplayText [s1p21c1l7]Analog4: %value% adc endon

Show BME280 + SGP30:

rule1 on tele-BME280#Temperature do DisplayText [s1p21x0y0]Temp: %value% C endon
      on tele-BME280#Humidity do DisplayText [s1p21x0y10]Hum : %value% %% endon
      on tele-BME280#Pressure do DisplayText [s1p21x0y20]Prss: %value% hPa endon
      on tele-SGP30#TVOC do DisplayText [s1p21x0y30]TVOC: %value% ppb endon
      on tele-SGP30#eCO2 do DisplayText [s1p21x0y40]eCO2: %value% ppm [s1p0x0y50]Time: [x35y50t] endon

Waveshare has two kinds of display controllers: with partial update and without partial update. The 2.9 inch driver is for partial update and should also support other Waveshare partial update models with modified WIDTH and HEIGHT parameters. The 4.2 inch driver is a hack which makes the full update display behave like a partial update and should probably work with other full update displays.

The drivers are subclasses of the Adafruit GFX library. The class hierarchy is LOWLEVEL :: Paint :: Renderer :: GFX, where:
GFX: unmodified Adafruit library
Renderer: the interface for Tasmota
Paint: the modified pixel driver for e-paper

• there are several virtual functions that can be subclassed down to LOWLEVEL.

The display dispatcher only does the class initialization call. All other calls go to the Renderer class.

In black and white displays, a local RAM buffer must be allocated before calling the driver. This must be set to zero on character or TFT color displays.

Remark: To use the 400x300 e-Paper display, the Arduino library 2.4 or later must be used because it leaves much more RAM available than prior versions. This display requires 15k of RAM!

The EPD fonts use about 9k space, which can be selected at compile time using #ifdef directives.

• SSD1306 - 1.15k
• EPD42 - 2.57k
• EPD29 - 2.1k
• Display and Render class - ~12k