Hi,
I am new to ESP, i am using a ESP 12e for Transmitting a score to slave board to master board, i have used max7219 to drive a 7 segment displays. i have built a circuit, but displays are not glowing, but the buzer is used to buzz is working.
ledcontrol.h is used and the pins GPIO4 as a DIn, for clk - GPIO0. and Load - GPIO2 of ESP12E
i found that the all segment pin A-G of max7219 are giving High output but the displays are not glowing,
can any body help me to complete please
8266.pdf (21.6 KB)
What 7-segment devices are you using for 'LED BIG' ?
If you look at the datasheet for your max7219, you will notice that logic Hi is a minimum of 3.5V and your ESP is a 3.3V device so you should not be using that chip to drive your 7 segment display. The datasheet states in the first paragraph that applications requiring 3V should use the MAX6951.
It also looks like you are driving 3 "LED BIG" and 1 regular (?) 7 segment display with each MAX7219 chip. They can only source 100mA. Is that enough to drive all 4 or your devices?
You also do not have current limiting resistors and D3 and D4 on your ESP.
I am using 1.8" 7 Segment LED's
Thanks for valued reply bro, can you just suggest me the solution for the same.
can i use pnp trasistor or schmitt trigger ic to boost the signal of Din, clk and CS.
can you please suggest me the best one bro
if i need to use Trasistor, which is the best to drive the voltage, please suggest me bro
Noted:
i found that i am not getting any voltage at clk and at cs - 2.65v and at Din 2.02v
when i input the score button CS is increasing to 2.65v to 2.95v
@springcs0 if you are debugging the display in the context of the entire project's code, stop.
Write a simple test program that exercises the display. Post that code here.
Your observations make no sense to me ATM. Post pictures of your wiring and a copy of the schematic your are working from.
Your problem could be anywhere.
a7
1 Like
Big 1.8" 7-segment displays can have multiple LEDs in series per segment (2-4), with a total Vf of close to 10volt. A 5volt MAX7219 might not have enough voltage to drive them.
Large displays are typically driven with TPIC chips and a 12volt supply.
But they don't like a 3.3volt-logic ESP.
Post the datasheet of your display, or the number that is printed on the side.
Leo..
Hi
This same Project is tried in Arduino Uno it was working fine 5V only,
i am using 2A adaptor 5V with output.
You can check out the attachment sir. i am using 6 such 7 segments and 0.56" two
Forward Current IF = 20mA/Segment, So 6 nos* 7 seg = 42 segments each need 20 mA
Total current need is 840 mA, i hope i have calculated correct.
HB18011ASR (1) 1.8 Inch.pdf (145.2 KB)
The .pdf shows three LEDs per segment, with a typical Vf of 5.5volt.
A MAX7219/Uno on 5volt might sort off work with reduced brightness, but is the wrong choice for these displays (see post#7).
Leo..
Bro, the brightness was perfect with Uno, why do you think its a wrong choice for ESP 12E, any how displays driven by MAX7219 only. is any thing i missed out, please let me know.
i am using level shifter i.e TXS0108E to drive Drive Max7219 with ESP12E
The 5volt power of an Uno might have given your 3LEDs per segment display 75% brightness, which could be OK for you. An ESP board, with USB backflow protection diode might only give 4.3volt to the display, leaving you in the dark.
Measure the supply pin of the MAX7219, and see if it's 5volt.
Leo..
Hi Bro
I have checked the voltages of Max7219 pins its 0.50 when its glowing, but before if was not glowing that movment it was -5.45v. i have rised the supply voltage to 5.5v by adding buck converter. even LEDs are started glowing after i measure what i wondered. (i have checked for loose connections also.) and i found their were no signal in Din and 3.28v in CLK and CS.
Bro can you tell me whats might be the problem with Signals
i found first MAX7219 LEDs are continueous glowing and second MAX7219 not glowing and no voltages at its pins.
is it ok i am using TXS0108e for rising a signal voltages beween Max and ESP12e, i found its not working.
check out the small pic
attached.
As I told you before, the MAX7219 is the wrong chip for these displays.
You never will get it right untill you re-design with TPIC chips.
Leo..
Ok, i got it Bro, ok any how i jumped in i want to give a try, i take your words.
Bro can you tell me how to check Din clk and CS signals from the ESP 12E.
You might already have fried the MAX7219 chips or level converter with that higher voltage.
Look at these pages for the TPIC driver.
Leo..
No bro MAX can take Upto 5.5v as per data sheet and even esp 12e also Vin pin can take upto 12V, Max7219 is working fine. and thanks for suggetions of TPIC, i will try to add the circuit and i check if my luck works.
can you suggest me, is their any ways to check the Din clk and CS signals with out Osciloscope. i am doubting on the signals.