What does open drain mean on a microcontroller?
The drain is open as in open-drain pin) If you recall about 2 minutes ago, we don’t want to leave pins floating so in most cases open-drain pins will have an external pullup resistor. If you are tricky (of course, you are), you can configure the MCU’s pull-up resistor and use the pin in open-drain output mode.
Can a 5V pin be set as an open drain pin?
1. I am using stm32f205. 2. MCU is powered by 3.3V. 3. Another ic pin is driven by 5V logic or (Vih = 0.7*VDD = 3.5V) 4. Can I set pin of STM32F2 as open drain & connect 5V by pull up to it. 5. Datasheet of MCU says that they are not true open drain pins.
How is the direction of an I / O pin controlled?
For most ports, the I/O pin’s direction (input or output) is controlled by the data direction register, called the TRIS register. TRIS controls the direction of PORT . A ‘1’ in the TRIS bit corre- sponds to that pin being an input, while a ‘0’ corresponds to that pin being an output.
What happens to the input pin on a microcontroller?
If any of the open-drains are pulling the line to zero, the input will be zero. Since none are ever pushing, you won’t have any digital infighting (which is worse than floating pins).
What do open drain outputs do in a circuit?
Open drain outputs act like a switch to ground. The resistor acts as a pullup for when none of the outputs are active. If you replace the open drain outputs in your circuit with buttons its easier to visualise: Thanks for contributing an answer to Electrical Engineering Stack Exchange!
What are the interrupt pins on a UC?
Each has an !INT pin which is open drain and pulled high to 5v through a resistor. Can I attach all of these pins together to effectively create a 10 input ‘AND’ of all the interrupt pins to be read by a uC? Additionally, each of these chips has a !RESET pin that also operate open drain and are pulled high to 5V through a resistor.