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Friday, August 12, 2016

Itron FG209M2 vfd display controlled by Arduino via 2 MAX6921

see about this article on HACKADAY ;)

   I give for tests an old vfd display made by Itron with 20 characters each made with 14 segments, point & comma.
   Janos, who is owner of this vfd display, made a interface with 2 MAX6921 integrated, using this schematic:
and PCB board is
   I redesigned schematic of vfd interface using Eagle PCB software
   After I study the datasheet of MAX6921, for send data to vfd display, classical style is:
 but in my case is little different because I have cascaded 2 MAX6921; for put on vfd display letter R on left corner must send this data:
with this notation of segments of character:
   For initial test, I made a simple schematic, using fist time an Arduino Mega board, than Arduino Uno:
   When upload VFD_FG209M2_2MAX6921_test1.ini sketch I see X letter moving from right to left of vfd display, like in video named 

   I made small steps (create characters, like in application note for MAX6954 (see
 until I simulate a clock with calendar and temperature and humidity using VFD_FG209M2_2MAX6921_test3j3c.ini sketch, see movie named afisaj VFD FG209M2 cu MAX6921 si Arduino (9)

   Finally, I put in schematic an RTC module with DS3231 (works fine with DS1307, too) and DHT22 module (AM2302 sensor + 4k7 resistor between +5V and DATA pin) for humidity and temperature:
   Using RTC_DHT_VFD_FG209M2_2MAX6921_ver4.ino I have on vfd display next texts:
   Because texts are in my native language (roumanian) I made few changes for have alternative indications:
NOTE: More details about steps in experiments can be writte in original article !

   I reduce previous sketch and remain just english text for day & day, current sketch is RTC_DHT_VFD_FG209M2_2MAX6921_ver4b.ino and you can see how is now in movie named clock on VFD FG209M2 display with MAX6921 and Arduino (3)


  1. Nice work! I wonder if you could post some of the details of the power supply you're using to driver the filament (heater)? In particular, are you using DC, or biased AC?

    1. sorry for delay... I ask the owner of vfd display and he tell me it us 5V AC and a general rull is tu use a value for tension until filament is few red in night condirions..