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Compiler/TMS570LC4357: Using LIN1 as SCI1, RX pin stuck at 3.3V

Samuel Homans
Prodigy 20 points
Part Number: TMS570LC4357
Other Parts Discussed in Thread: HALCOGEN,

Tool/software: TI C/C++ Compiler

Using HALCoGen 4.07.01 and CCS 8.3

I'm trying to configure the LIN1 pins on the TMS570LC4357 to be used as SCI1 pins. The TX pin should have a pull up resistor and the RX pin should be an input that idles at 0 volts. Even with configuring HALCoGen this way the SCI1 RX pin reads 3.3 volts and the receive interrupt will not trigger. Has anyone ran into this problem before or know how to ensure the RX pin is at 0 volts.

  • 0
    TI__Guru**** 197036 points

    Hello,

    Both SCI TX and RX are in NORETURN to ZERO (NRZ) format. This means that the TX line and RX line are at logic HIGH when IDLE. The data transmission begins with s START bit, in which the transmitter pulls the SCI line low.

  • 0 in reply to QJ Wang
    TI__Guru**** 197036 points

    Hi Sam,

    The SCI allows two devices to communicate across the serial bus. The SCI1/LIN1 has been used by TM4C129 on board for virtual COM port. Can you please use SCI3 for your test which is located on J1 connector (Pin3 and Pin4)?

    If you get the same issue by using SCI3, please let us know. Thanks