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Hi,

Can you show me your schematic? or show the diagram of the connection for the TXb0104? then I can be clear for your design.

Also, I need to know is it appears power on or all power supply is OK, you just put the button to add the pull down resistor? for the A side, any pull up resistor added or any driver drive it?

I need to know your clear applicaiton and what is your target and what is the status of the A side.

BR

Junjie

in this iteration the port "digital" is input only. it level shifts a 5v pulse from external electronics for the 3.3v tolerant gpios.  A TXB0104 was used to allow bidirectional interfaces in the future. The other ports where used because they were convenient, but are not critical.

the button is temporary - purely for software development.

On pressing the button, A and B side both go high and stay high. A holds at approximately 3.3v and B holds at approx 5v.  There is a wire between jp9 and p9. if this is pulled both A and B remain high.  A pulldown resistor on side A will pull both A and B low when it is connected, but once it is connected it has no more effect. Attempting to drive A low from the micro causes the micro to become unstable and the port to oscillate.

I can supply trace snapshots tommorow

ta

stu

Simulate your digital signal with two pushbuttons, one to VCC and one to GND.

Hi,

Yes, if you want to simulate this, please add two buttons, one to Vcc to simulate high, one to GND to simulation "Low".

this TXB familiy part needs the driver has a little stronger drive capability. Your 56Kohms is a little higer can not raise the original high to low.  any further questions, please let me know.

BR
Junjie