Contents
How to test the speed of Port manipulation?
To test the speed of port manipulation vs. using digitalWrite (), we will use the circuit in the image. Now to analyse the output at digital pins zero and seven using a digital storage oscilloscope. Our first test sketch turns on and off digital pins 0~7 without any delay between PORTD commands – in other words, as fast as possible. The sketch:
Why do you use port manipulation on Arduino?
In this article we are going to examine Arduino I/O pins in more detail by using “Port Manipulation” to control them in a much faster manner than using digitalWrite ()/digitalRead (). Why? Speed! Using this method allows for much faster I/O control, and we can control or read groups of I/O pins simultaneously, not one at a time; Memory!
How are port registers used in a microcontroller?
First, we’ll use the I/O as outputs. There are three port registers that we can alter to set the status of the digital and analogue I/O pins. A port register can be thought of as a special byte variable that we can change which is read by the microcontroller, therefore controlling the state of various I/O ports.
Which is the direction register for Port d?
DDRD is the direction register for Port D (Arduino digital pins 0-7). The bits in this register control whether the pins in PORTD are configured as inputs or outputs so, for example:
How does port manipulation work on an Arduino?
If this function is still too slow, port manipulation could help. There is a great introduction about the topic on the Arduino website. In a nutshell what it is about, is setting output pins directly, according to the data sheet. This is the fastest possible method of manipulating registers and hence output pin states.
How much does digitalWrite do for Port manipulation?
Benchmarks digitalWrite digitalWriteFast Port manipulation (single bit) (entire p t µ 5 µs µ 1.75 µs µ 0.125 µs 62.5 ns n 80 28 2 1 × 1 2.86 40 80