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Original question:

TXB0104: TXB0104QPWRQ1 DATA TRANSFER PROBLEM

TXB0104: UART signal is being chopped

Murilo F
Prodigy 10 points
Part Number: TXB0104
Other Parts Discussed in Thread: TXS0104E

Hello everyone,

I'm doing a project with two custom boards, with a ESP32-S3-WROOM-1 in the master board and a STM8S003 in another. For communication these boards have been set a UART channel in both( data length : 8bits, stop bits : 1, parity: disable, baudrate : 9600 ). For this cause I have to use a shifter voltage level (TXB0104), because esp works in 3.3V and stm8 5V. That uart cable is follow by +12V for supply and GND.

When I connect them, the TX signal from ESP32 is chopped to 2V since it pin, if I turn on only esp32. I thought was a mistake with the translator voltage level, but I put a pull up resistor and nothing happen. I test the main board alone and the signal TX from esp32 seens okay, but after the translator, its chopped too. I tried a pull up resistor, but nothing change.

TXB0104 (SCL and SDA connections is from RTC, but it´s disabled)

Esp32 connections

Esp32 connections

send signal in A3 TXB0104

send signal in A3 TXB0104

send signal in B3 TXB0104

Gratefully,
Murilo.

  • 0
    Guru 243220 points

    The TXB has a drive strength of 20 µA (so it does not work with pull-up/-down resistors), and requires a much higher drive strength from other devices.

    Anyway, the TXB does not work with I²C signals. For that, you would require something like the TXS0104E, which also works with UART signals. (The TXS does not work with pull-down resistors.)

  • +1 in reply to Clemens Ladisch
    Prodigy 10 points

    Thank you for reply, I'll try this later for better my signal, but I discovered that my problem is a short in STM8S, the RX pin and GND are connect internally.