These boards (affiliate link) only cost a bit more than $2/piece and you can connect several of them by daisy chaining one with the next. This allows you to create wonderful led bar on the cheap: lets say you buy 10 of them plus an ESP8266 and mount them on a piece of card board you’ll have a wonderful remote programmable eye catcher for shop display for less than $30!
Not being fluent anymore in C/C++ I had to get used again to the hard work of managing memory, dealing with a weird String object (yes, even weirder than the String object in Java;-)) and some other pitfalls for a 10+ years Java programmer.
But I finally managed it and here you can see the result:
Connect the Modules like this:
| Led Matrix | ESP8266 |
|---|---|
| VCC | +3.3V |
| GND | GND |
| DIN | GPIO13 (HSPID) |
| CS | Choose free GPIO, e.g. GPIO2 |
| CLK | GPIO14 (HSPICLK) |
Here you’ll find the library:
https://github.com/squix78/MAX7219LedMatrix
Please note:
- this library is made for the ESP8266 and might or might not work for “normal” Arduino boards.
- I had to patch the Mac OS X release with the SPI folder from Github. In other words there wasn’t an up-to-date release for Mac OS X (and maybe for the other platforms as well) and the SPI.h/SPI.cpp wouldn’t compile
Now a beer! Did you like this post? It often takes me several hours of my free time to write one. If I was your neighbour would you offer me a beer for the hard work I did for you? The beauty is: beers can be teletransported with a painless donation using Paypal. A beer in a Swiss bar costs about USD $4.80. Or use this affiliate link if you order something on Banggood and I'll get a small kickback. Thank you!
Hi Dani,
My matrixes arrived yesterday and I've been playing with them on an Arduino just to make sure I built them properly. Everything checks out.
Now I'm trying to move to the ESP and I'm having compile problems.
I tried Arduino 1.6.4 and I get these errors (I hope they'll copy in here…)
Arduino: 1.6.4 (Windows 8.1), Board: "Generic ESP8266 Module, 80 MHz, 115200, 512K (64K SPIFFS)"
Build options changed, rebuilding all
C:Program FilesArduinolibrariesMAX7219LedMatrix-masterLedMatrix.cpp: In member function 'void LedMatrix::scrollTextLeft()':
C:Program FilesArduinolibrariesMAX7219LedMatrix-masterLedMatrix.cpp:122:18: error: ambiguous overload for 'operator=' (operand types are 'String' and 'int')
myNextText = NULL;
^
C:Program FilesArduinolibrariesMAX7219LedMatrix-masterLedMatrix.cpp:122:18: note: candidates are:
In file included from C:UsersMichaelAppDataRoamingArduino15packagesesp8266hardwareesp82661.6.4-628-g545ffdecoresesp8266/Arduino.h:209:0,
from C:UsersMichaelAppDataRoamingArduino15packagesesp8266hardwareesp82661.6.4-628-g545ffdelibrariesSPI/SPI.h:24,
from C:Program FilesArduinolibrariesMAX7219LedMatrix-masterLedMatrix.cpp:2:
C:UsersMichaelAppDataRoamingArduino15packagesesp8266hardwareesp82661.6.4-628-g545ffdecoresesp8266/WString.h:85:18: note: String& String::operator=(const String&)
String & operator =(const String &rhs);
^
C:UsersMichaelAppDataRoamingArduino15packagesesp8266hardwareesp82661.6.4-628-g545ffdecoresesp8266/WString.h:86:18: note: String& String::operator=(const char*)
String & operator =(const char *cstr);
^
C:UsersMichaelAppDataRoamingArduino15packagesesp8266hardwareesp82661.6.4-628-g545ffdecoresesp8266/WString.h:87:18: note: String& String::operator=(const __FlashStringHelper*)
String & operator = (const __FlashStringHelper *str);
^
C:UsersMichaelAppDataRoamingArduino15packagesesp8266hardwareesp82661.6.4-628-g545ffdecoresesp8266/WString.h:89:18: note: String& String::operator=(String&&)
String & operator =(String &&rval);
^
C:UsersMichaelAppDataRoamingArduino15packagesesp8266hardwareesp82661.6.4-628-g545ffdecoresesp8266/WString.h:90:18: note: String& String::operator=(StringSumHelper&&)
String & operator =(StringSumHelper &&rval);
^
Error compiling.
This report would have more information with
"Show verbose output during compilation"
enabled in File > Preferences.
I didn't do the verbose messages – would that help?
Have you seen these kind of errors before?
Hi Mike. Thanks for your feedback. I'll have to see what exactly changed… I hope to get back to you soon…
Got the same problem here. Any updates ?
Hi Dani, I'm reza.
Nice work!
I can compile and upload to my ESP-12 but the Led Matrix doesn't show the word i want (just blinking and turn the leds randomly).
I use DIN at GPIO13, CS at GPIO12, and CLK at GPIO14.
Can you fixed the error please?
Thanks
same here
My 8×8 (4 off) are already joined together as a unit and the letters scroll vertically. Basically I'm asking if I can alter the code to swing the matrix character map through 90 degrees. thanks
John
I am having the same issue, did you find a way around this?