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ISO6721: HOW TO CONNECT ISO6721 BETWEEN A MICRCONTROLLER AND A USB-UART CONVERTER CHIP

Sumit Mourya
Expert 1790 points
Part Number: ISO6721

Hello All,

I'm trying to use ISO6721 as digital UART isolator between my MCU and CP2102 .

I wanted to know about the TX, RX connections between the IC's.

 MCU TX to ISO6721 pin No. 2 (OUTA) 

 MCU RX to ISO6721 pin No. 2 (INB) 

CP2102 RX to ISO6721 pin No. 6 (OUTB) 

CP2102 TX to ISO6721 pin No. 7 (INA) 

Is the above connection correct?

  • 0
    TI__Mastermind 26670 points

    Hello,

    Thank you for your question. The UART protocol will require the connections: MCU TX to CP2102 RX and the CP2102 TX to the MCU RX. Based on the pin configurations you've listed it sounds like your are using the ISO6721B device with the CP2102 on the left of the isolator and the MCU on the right, is this correct? To achieve this with the ISO6721B, make the following connections:

    MCU TX to ISO6721 pin No. 7 (INA)

    MCU RX to ISO6721 pin No. 6 (OUTB)

    CP2102 RX to ISO6721 pin No. 2 (OUTA)

    CP2102 TX to ISO6721 pin No. 3 (INB)

    I've also attached an example UART isolation block diagram from our "Isolating UART Signals" one pager below for your reference, please note this example system is for a different application then your own but the TX and RX configuration and direction will be the same. 

    Regards,
    Darrah

  • 0 in reply to Darrah Merillat
    Expert 1790 points

    Hello Darrah,

    Thank you for the reply.

    The MCU is on the left side of ISO6721B and CP2102 is on the right side on the PCB.

    The below configuration should also work 

    MCU TX to ISO6721 pin No. 3 (INB)

    MCU RX to ISO6721 pin No. 2 (OUTA)

    CP2102 RX to ISO6721 pin No. 6 (OUTB)

    CP2102 TX to ISO6721 pin No. 7 (INA)

    Basically, The TX lines are for IN Pins & RX lines are for OUT Pins. 

    Is this correct?

    Otherwise I will Design the PCB as per your configuration.

  • 0 in reply to Sumit Mourya
    TI__Mastermind 26670 points

    Hello,

    Yes you are correct, TX lines should connect to the IN pins and the RX lines should connect to the OUT pins. If the MCU is connected to the left side of the ISO6721B and the CP2101 is connected to the right side then the connections you have listed are correct.

    Regards,
    Darrah