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Author Topic: circuit diagram  (Read 508 times)

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Offline saroseTopic starter

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circuit diagram
« on: December 03, 2020, 10:58:38 am »
Why is it recommended to use diodes and resistors for serial communication as shown in the circuit given? It is given in datasheet of SIM800C. Why we cannot directly connect TX and RX?
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Offline Manul

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Re: circuit diagram
« Reply #1 on: December 03, 2020, 11:37:22 am »
It is primitive level shifting. UART devices need to use same logic levels, like for example 0-5V. If two devices use different logic levels, then you need level conversion to not drive 3.3V input with 5V output for example.
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