# SPI pins logic level issue [closed]

I have ESP32 and the popular dot matrix module MAX7219 8*8 module to interface. It is connected through SPI pins. After a sample word printing on the maxtix it shows garbage outputs. Is it happening due to the logic level issue? Because the dot matrix works on 5V and ESP32 has 3.3v.

• Sorry, you'll have to do much more debugging on your own. What's the acceptable input logic levels, according to the data sheet? What does the ESP32 output? – Marcus Müller Jul 14 '19 at 12:40
• It is indeed out of spec, but I wouldn't be surprised if once the levels are boosted there turns out to be another problem more directly causative problem like a software or wiring mistake as well. – Chris Stratton Jul 14 '19 at 20:06

Page 3 of the MAX7129 datasheet specifies a minimum logic-high input voltage $$\\mathrm{V_{IH}}\$$ of 3.5V. So if your ESP32 is a 3.3V device then it cannot provide a high enough voltage to reliably operate the MAX7129. So yes, voltage levels / logic levels are probably the culprit here.