See datasheet of SHT75:
To avoid signal contention the microcontroller must only drive DATA low. An external pull-up resistor
(e.g. 10 kΩ) is required to pull the signal high – it should be noted that pull-up resistors may be included in I/O circuits of microcontrollers.
So best would be to configure the pin as "Resistive pull up" initial drive high. Then you may write low to the sensor and while written high you may read from the pin.
thanks for your kind reply.
In the configuration you suggested me, would the data line of the sensor be able to pull the PSoC pin down to 0 when required? As per the datasheet, after a command is sent to the sensor (8 clock pluses with 8 data bits), a ninth clock pulse should be issued and the data line should go down to 0.
would the data line of the sensor be able to pull the PSoC pin down to 0 when required?
thank you for your answer. I did some tests this morning with the following setup:
- clock line as output pin - strong drive
- data line as bidirectional pin, resistive pull up and initial state as HIGH.
I did some tests looking at the data and clock signals during some basic procedures (start transmission and reset communications), and the signals are as expected. When I send a command to the sensor (start transmission procedure + command sent as per datasheet specs), I expect the sensor to push the data line low after the ninth clock pulse. But what happens, as you can see from the attached image, is that the data line goes down after receiving the 8 bits of the command, but then at the clock pulse, goes up (not to Vdd, but a little lower): do you have any suggestions about what could cause this problem?
Thank you very much in advance,