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[SOLVED] help please : RS232 1.8v to 5 volt level shifter

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mahsoft

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hi
i need to communicate between pic micro-controller that run on vcc 5v ,, gps module sim18 that work on 1.8v

how i can get two to work together TX/RX ??????

there any circuit for voltage shift level ??

or any ic can do this work ?
 

Hai mahsoft,

If a device support UART, then the hardware of the pin will have the ability to tolerate the voltages. I guess the same can be applicable for the gps module. But i didn't used it before so i would like to refer the circuit which i have attached with this.

1_1325505954.jpg


This circuit has been used to shift the level from +5V to -5V I2C bus. I hope u know how to modify the circuit for ur application.
 

please my voltage level exist in this photo
sim18.jpg
 

Dear mahsoft..

Please find the picture which is modified for your circuit. Please try to implement with breadboard. If it is working properly then u can go for next step.

0_1325569761.jpg


Tx should be connected to microcontroller tx and rx to gps module rx.

this same circuit u have to copy to connect gps module tx and microcontroller rx. Remember 2 circuits of those u need

and u have to replace the 1.8V to 5 V and 5 V to 1.8V for the gps tx to mcu rx
 
Last edited:
thank you karthikkrv85
i will test it and reply on you soon

---------- Post added at 11:46 ---------- Previous post was at 11:34 ----------

please >>>>>>>>> what the model number for this transistor or general pnp and npn
 

hai..

I have just given generally.. i think u can select the one which can satisfies the switching speed of ur application
 

i do it in proteus >>>>>>>> when input 5 v get me 1.8 in rx
but when input zero get me 1.8 in rx too
there no change
please check resistor 100
maybe you mean 100k
because i change it to 100k and get me low voltage at rx
 

hai... i dont have proteus to simulate. But i have tried with another one. it is a java applet for ipad application. In that i saw it is working with that same 100 ohms.

please recheck.. may be the simulator needs to restart when u change the input voltage.. why dont u apply some square wave as a input and verify. because i have tried with square wave.

ur application is working with that 100k?
 

yes my application work with 100k in simulation and with analysis 100 ohm is very small coz it will get high on base every time so not can sense with input zero
therefor i put 100k to make base pull up and can sense with zero voltage >>>>>>>
Thank you for ur help >best wishes for you
 

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