SN74LV245A as level shifter: How to use the DIR pin

The DIR pin on the SN74LV245A defines whether the A pins or the B pins are the input pins.

• If DIR is low (i.e. connected to GND), allB pins are inputs and all A pins are outputs.
• If DIR is high (i.e. connected to Vcc), all A pins are inputs and all B pins are outputs.