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Build Display message system with WI-FI micro controller

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The MAX7219 8-bit LED display module is one of the most popular and widely used display modules and has been used in many 8/16/32-bit MCU projects. It is time to see it working in the ESP8266 CBDBv2 EVO ecosystem. The MAX7219 is a compact serial input/output common cathode.

Build Display message system with WI-FI micro controller

The display driver connects the microprocessor (μP) to a 7-segment digital LED display with up to 8 digits, a bar graph displays or 64 individual LEDs. On-chip includes BCD code B decoder, multi-channel scanning circuit, segment and digital drivers, and 8×8 static RAM for storing each digit. A segmentation current can be set for all LEDs with an external resistor.

A convenient 4-wire serial interface connects all common μPs. Individual numbers can be addressed and updated without overwriting the entire display. The MAX7219 also allows the user to select either code B decoding or no decoding for each number.

These devices include a 150μA low-power shutdown mode, analog and digital brightness control, a scan limit register that allows the user to display 1 to 8 digits, and a test mode that forces all LEDs to illuminate. This is a 5V operating device. If you need to run it in a 3.3V logic level book, you will A level shifter is required.

Collect the hardware

Build Display message system with WI-FI micro controller

Build Display message system with WI-FI micro controller

Build Display message system with WI-FI micro controller

Make the wiring

Wire up the everything as mention below

Build Display message system with WI-FI micro controller

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Build Display message system with WI-FI micro controller

Build Display message system with WI-FI micro controller

//– MAX7219 registers

MAXREG_DECODEMODE = 0x09

MAXREG_INTENSITY  = 0x0a

MAXREG_SCANLIMIT  = 0x0b

MAXREG_SHUTDOWN   = 0x0c

MAXREG_DISPTEST   = 0x0f

DIN   = 7      — 13 – data in pin

CS    = 6      — 12 – load (CS) pin

CLK   = 5      — 14 – clock pin

gpio.mode(DIN,gpio.OUTPUT)

gpio.mode(CS,gpio.OUTPUT)

gpio.mode(CLK,gpio.OUTPUT)

 

 

//2. Write serialised data

 

function wrByte(data)

i=8

while (i>0)

do

mask = bit.lshift(0x01,i-1)

–print(mask)

gpio.write( CLK, 0)    — tick

dser = bit.band(data,mask)

if (dser > 0)

then gpio.write(DIN, 1)   — send 1

–print(“1”)

else gpio.write(DIN, 0)   — send 0

–print(“0”)

end –endif

–print(dser)

gpio.write( CLK, 1)    — tick

i=i-1

end –while

end

 

 

//3. Set Register

 

function setReg(reg, value)

gpio.write(CS, 0)

 

wrByte(reg)   — specify register

tmr.delay(10)

wrByte(value) — send data

 

gpio.write(CS, 0)

–tmr.delay(10)

gpio.write(CS, 1)

end

 

 

//4. Convert anf Print integer number in xxxx format

 

function print_led_int(c)

th = string.format(“%d”,c / 1000)

h = string.format(“%d”,(c-th*1000) / 100)

t = string.format(“%d”, (c-th1000-h100) / 10)

u = string.format(“%d”, c-th1000-h100-t*10)

–print(string.format(“%d %d %d %d”, th,h,t,u))

setReg(4, th)

setReg(3, h)

setReg(2, t)

setReg(1, u)

end

 

 

//5. Create a Display ‘ZERO’ init stage

 

function zero_all()

v=1

while (v<9) do

setReg(v,0)

v=v+1

end

end

 

 

  1. MAX7219 Initialisation

 

setReg(MAXREG_SCANLIMIT, 0x07)

tmr.delay(100)

setReg(MAXREG_DECODEMODE, 0xFF)    — full decode mode BCD

tmr.delay(100)

setReg(MAXREG_SHUTDOWN, 0x01)          — not in shutdown mode

tmr.delay(100)

setReg(MAXREG_DISPTEST, 0x00)              — no display test

tmr.delay(100)

setReg(MAXREG_INTENSITY, 0x00)            — set Brightness

zero_all()                                — set all to ZERO

 

 

//7. Test Display – 9999 counter

 

count=0

tmr.alarm(0,1000,1,

function()

count=count+1;

–print(count);

print_led_int(count)

if (count>9999) then count=0;zero_all()

end

end)

TESTING

 After the uploading it will prompt in the browser and start displaying this html file which is mention below

Build Display message system with WI-FI micro controller

When you click on the Enter Message it will start displaying the Text on the Dot matrix
Build Display message system with WI-FI micro controller