mirror of
https://github.com/xodio/xod.git
synced 2026-03-14 20:56:52 +01:00
63 lines
2.1 KiB
Markdown
63 lines
2.1 KiB
Markdown
---
|
||
title: Pulses
|
||
---
|
||
|
||
# #21. Pulses
|
||
|
||
<div class="ui segment note">
|
||
<span class="ui ribbon label">Note</span>
|
||
This is a web-version of a tutorial chapter embedded right into the XOD IDE.
|
||
To get a better learning experience we recommend to install the
|
||
<a href="/downloads/">desktop IDE</a> or start the
|
||
<a href="/ide/">browser-based IDE</a>, and you’ll see the same tutorial there.
|
||
</div>
|
||
|
||
In the [tenth chapter](../10-math/), we briefly mentioned the blue `UPD` input
|
||
pin and the *pulse* data type.
|
||
|
||
This type is very different from all the others. All values in the XOD are
|
||
transferred to the links continuously, even if the values haven't changed. The
|
||
pulse data type is different. Imagine something like a flash. It’s basically a
|
||
message to trigger something else. It does not transmit any data. However, it
|
||
is useful when you need to convey that an event has occurred or tell something
|
||
else to work.
|
||
|
||
For example, say you only want an `analog-input` node to receive information
|
||
from a board port at certain intervals, and not all the time. This frequency
|
||
can be set with the help of pulses.
|
||
|
||
|
||
|
||
Each time a pulse arrives on the `UPD` pin, the node reads the analog port and
|
||
outputs the value to the `VAL` pin. This value will be stored there until it
|
||
changes to another value.
|
||
|
||
The behavior of the `UPD` pin can also be set in the Inspector. For a pot the
|
||
choice means:
|
||
|
||
* `Never`: Never produce pulses, i.e. Do not take readings from the analog port
|
||
at all.
|
||
* `On boot`: Generate a pulse once at startup. We will update the state exactly
|
||
once.
|
||
* `Continuously`: Generate pulses constantly, i.e. take the readings from the
|
||
analog port with the highest possible rate.
|
||
|
||
## Test circuit
|
||
|
||
|
||
|
||
[↓ Download as a Fritzing project](./circuit.fzz)
|
||
|
||
## How-to
|
||
|
||
1. Open the Inspector for the `pot` node.
|
||
2. Change the `UPD` value to `On boot`.
|
||
3. Upload the patch to the Arduino.
|
||
|
||
|
||
|
||
Turn the potentiometer knob and press the reset button on the board itself.
|
||
Note, the potentiometer updates now only once when the Arduino is turned on.
|
||
|
||
[Next lesson →](../22-clock/)
|