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[SOLVED] pin level (3.3V-5V) and rs 232

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dxtr

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Hey everyone
i wish you could help me with this problem
i want to use the µdrive-uSD-G1 with PIC 16F876A using Rs232

**broken link removed**

the problem is that the µdrive Tx-Rx levels are 0-3.3V , the pic Tx-Rx levels are 0-5V , how to manage that ?
 

Hi,

There are a few chips around that will solve your problem, though they are somewhat limited in stockists.
https://www.ti.com/lit/ds/symlink/txb0106.pdf

If you see the Microchip Tips and Tricks pdf it shows many other ways to convert the voltages

Another way is to use a Pic chip that will run at 3v3 like the 16LF876a, though that depends on what other devices are connected that may be 5v devices
 
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    dxtr

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I don't know anything about the udrive, but the PIC should do fine with 3.3V logic levels on the inputs. However, can the udrive accept 5v inputs? if not, you could just use a voltage divider on that line, you don't need a chip.
 
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thanks wp100
barry said:
I don't know anything about the udrive, but the PIC should do fine with 3.3V logic levels on the inputs. However, can the udrive accept 5v inputs? if not, you could just use a voltage divider on that line, you don't need a chip.
Click to expand...
barry : thanks , i read in the datasheet of udrive that if the host send 5v to Rx of the module , then you must put a 220 ohms resistor inline , so if the pic REALLY have no problem with 3.3 logic level then problem solved :)
 

Just put voltage divider from 5v to 3V3 side. In oppisite direction 3V3 can be considered as high logic level (see TTL voltage levels). I used that for xBee and works fine. For more protction of 3V3 inputs you can also pud zener 3V6 to asure that line never goes on 5V.
 
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electronicsbasecom said:
Just put voltage divider from 5v to 3V3 side. In oppisite direction 3V3 can be considered as high logic level (see TTL voltage levels). I used that for xBee and works fine. For more protction of 3V3 inputs you can also pud zener 3V6 to asure that line never goes on 5V.
Click to expand...
Thank you my friend :)
 

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