mheruian
Junior Member level 3
Hi Folks,
I'm newbie to electronics and been trying hard to understand what I don't understand, I have a DIY project in school where I have to integrate arduino to an SPI device, I have arduino nano that is 5v while my SPI device that'll be a slave works on 3v3 volts. I don't have other fancy mosfet or logic level shifter ICs, etc. Only transistors and diodes, resistors. I found this one example that works on SPI they said:
I had swap n-mosfet with my 2n3904 npn transistor here and it works like magic where if on HV1, i input logic high / 5v, LV1 produces 3v3 but when I input logic low / 0v on HV1, LV1 produces 1v9.. why is it high? How can I make it < 0v3 value??
also, i would like to ask some silly but technical question. I know how transistors and mosfet works (maybe??) since I used them where when you input high (voltage/current) on base/gate, the voltage/current on collector/drain will flow on emitter/source right? (like a switch)? so how come the 5v on HV1 doesn't flow fully 4 to 5 volt value on LV1 knowing the mosfet/transistor's base/gate is always high? Current chooses low potential path so 5v input on HV1 wont flow on 10k resistors of HV or LV right? How is the "FLOW" works actually in this logic level shifter?
I hope you could help me out. Been brain dead yesterday. Just self studying electronics, not schooling, etc. I don't have any mentor or adviser or someone that has opinion here.
I'm newbie to electronics and been trying hard to understand what I don't understand, I have a DIY project in school where I have to integrate arduino to an SPI device, I have arduino nano that is 5v while my SPI device that'll be a slave works on 3v3 volts. I don't have other fancy mosfet or logic level shifter ICs, etc. Only transistors and diodes, resistors. I found this one example that works on SPI they said:
I had swap n-mosfet with my 2n3904 npn transistor here and it works like magic where if on HV1, i input logic high / 5v, LV1 produces 3v3 but when I input logic low / 0v on HV1, LV1 produces 1v9.. why is it high? How can I make it < 0v3 value??
also, i would like to ask some silly but technical question. I know how transistors and mosfet works (maybe??) since I used them where when you input high (voltage/current) on base/gate, the voltage/current on collector/drain will flow on emitter/source right? (like a switch)? so how come the 5v on HV1 doesn't flow fully 4 to 5 volt value on LV1 knowing the mosfet/transistor's base/gate is always high? Current chooses low potential path so 5v input on HV1 wont flow on 10k resistors of HV or LV right? How is the "FLOW" works actually in this logic level shifter?
I hope you could help me out. Been brain dead yesterday. Just self studying electronics, not schooling, etc. I don't have any mentor or adviser or someone that has opinion here.