YoctoHubs can automatically publish sensor values on a MQTT broker, as we illustrated in a previous post on this topic. However, for scalability and security reasons, YoctoHubs cannot use MQTT messages to drive connected modules. There are however circumstances where it might be desirable to integrade Yoctopuce command devices in an existing MQTT architecture. In this case, it is enough to use a small gateway between the MQTT protocol and the Yoctopuce modules. This is what we are going to do this week.
A noticeable characteristic of Yoctopuce modules is that you can drive them from a server thanks to the HTTP callback API allowing you to work around NAT filters. Obviously, this is truly interesting only if you have a PHP, Java, or ecmascript server. Well, this week we tested some free PHP hosts and we show you in details how to configure them...
There is no magical sensor able to measure air quality in any circumstance: for each environment, you must select the appropriate sensor. We have already presented in this blog some ways to evaluate inside air quality, in particular to detect stale air because of CO2. We also talked about sensors that you can use to detect toxic or foul smelling gases, used in particular in the industry. Today, we address how to measure the quality of outside air, that is, the air that everyone breathes daily.
Generally, we always try to use sensors which do not require any calibration. But, in some cases, we cannot work around this step, in particular if you need to compensate an external perturbation. All the Yoctopuce sensors have the possibility to automatically apply a correction to the value returned by the sensor. Let's see how it works.
The issue with most screens is that they need to be constantly powered to display information. There is however an exception: the e-paper (or electronic paper) technology. This week, we take advantage of this technology to build a connected screen able to work for months on a single battery charge.
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