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).
Why do microcontrollers use pull up and pull down resistors?
As you stated, using pullup/pulldown resistors on pins expected to be output pins can be there to guarantee an input state. This is done to mitigate firmware/MCU failure, but will only work to protect against Hi-impedance state (basically the pin is configured as input by accident).
How are GPIO pins used in microcontrollers?
They are used on inputs to prevent floating lines, rapidly switching between high and low and a middle “undefined” region. Outputs normally do not need them. But most mcu pins are GPIO, and sometimes on startup are defined as inputs instead of outputs.
How big is a push pull output on a microcontroller?
A typical push-pull output is able to source/sink around +/-8ma where a high drive output may be up to +/-40ma. Again, that “Electrical Characteristics” section of the datasheet is your goto source for the details.
How does a GPIO output on a microcontroller work?
A push-pull output is another aptly-named GPIO mode. The pin has the ability to “push” the signal high or “pull” it low. It does this using a pair of complementary transistors. You have probably heard of “CMOS” technology.
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.
Which is the simplest input / output mode for a microcontroller?
The Stratify Toolbox is a printf ()-ing awesome debug tool! Check it Out! GPIO (aka General Purpose input/output) is the simplest of microcontroller IO. Even so, GPIO comes in various types and varieties. There is input, output, pull-up, pull-down, push-pull, high-drive, open-drain, and more.
How are PWM signals generated in a PIC microcontroller?
In PIC microcontrollers PWM signals can be generated using the Compare, Capture and PWM (CCP) modules by setting the required Registers, we have already learnt how to do that in the PIC PWM tutorial. But there is one considerable drawback with that method. The PIC16F877A can generate PWM signals only on pins RC1 and RC2, if we use the CCP modules.
Do you need a programmer to program a PIC microcontroller?
In fact it is the only way to program PIC microcontrollers so you will find the ICSP interface on all devices. All you need is a programmer that provides the ICSP connector (usually a six pin molex/dupont connector) which you plug into your target board.