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TM4C1230C3PM: If PB0 is set to U1Rx, USB0ID function, can it be used with 5V Tolerant?

K.Z
Expert 2490 points
Part Number: TM4C1230C3PM

Tool/software:

Hi All,

Currently, in our circuit, a transceiver (ST485EBDR) is connected for RS485 communication, and
RO - PB0 (U1Rx)
DI - PB1 (U1Tx)
are connected, and we would like to supply 5V to the transceiver.

Is the following correct regarding the functionality of PB0?
• GPIO Input: 3.6V tolerant
• U1Rx: TTL level (5V)
• USB0ID: 5V tolerant
※Note: Be cautious when supplying 5V until the functionality is changed to U1Rx/USB0ID

(PB0/PB1/PJ0/PJ1) are also specified as 3.6V tolerant.

Best Regards,

Ito

  • +1
    TI__Guru**** 191486 points

    Hi,

    K.Z said:
    Currently, in our circuit, a transceiver (ST485EBDR) is connected for RS485 communication, and
    RO - PB0 (U1Rx)
    DI - PB1 (U1Tx)
    are connected, and we would like to supply 5V to the transceiver.

    Hi,

      I find the below electrical characteristics for ST485EBDR. The MCU's PB0 will be connected to ST485EBDR's RO pin, correct? If ST485EBDR is operating at 5V then it means the VOH will be 

      

    K.Z said:
    Is the following correct regarding the functionality of PB0?
    • GPIO Input: 3.6V tolerant
    • U1Rx: TTL level (5V)
    • USB0ID: 5V tolerant
    ※Note: Be cautious when supplying 5V until the functionality is changed to U1Rx/USB0ID

    Please refer to the MCU datasheet. As you can see the PB0/PB1 are not 5V tolerant. You cannot drive a 5V to PB0 when it is configured for U1Rx. You can only drive 5V to PB0 when it is a USB0ID analog pin.