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Category: Articles
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Published on Monday, 06 May 2019 16:55
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Written by AltonaLab
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AltonaLab has a specially developed concept for connecting analogue inputs GPIO with sensors and controlling relays from digital outputs.
Connecting analogue inputs 0..5V to sensors with output 0..5V:
For analogue inputs operating in range 0..5V, an extension board has been developed to allow easy connection of up to 4 sensors to analog inputs. In this board, the connection of the analog input and the sensor is direct, so there is no need for a mathematical transformation of sensor readings. The board has two power supply connectors, one of them is to power the board, the other is to power the next one board, if it is needed. Power supply of the board is 5V.
Connecting analogue inputs 0..3.3V to sensors with output 0..5V:
For analogue inputs operating in range 0..3.3V, an expansion board has a resistor divider for each analog input. In this case the conversion of the signal is:
Vout = Vin * (R2/(R1+R2)), where R1=1k, R2=2k, so Vout = Vin * 0.666666;
The board has two power supply connectors, one of them is to power the board, the other is to power the next one board, if it is needed. Power supply of the board is 5V.
Connecting digital inputs to contact sensors:
The output of some sensors are normal close contact. An example of this kind of sensors is Alarm sensor (PIR). The extension board below allows to connect up to 4 contact sensors to digital inputs. The board has two power supplies, one of them is +5V to supply the resistor which is consecutively connected after the contact. The other power supply depends on the voltage supply of the sensor. If the sensors needs 12V power supply, then to +Pow screw needs to be connected +12V. Then this 12V will be leaded to all the +Pow screws of all the sensors connectors.
Connecting fast contact sensor to analog input:
Some contact sensors are very fast, the contact Turns ON for milliseconds. For this case is developed the board below. When the contact is closed for short time, the output of the board will become at 5V for period between 2 and 8 seconds. The time duration depends of the potentiometer on the board. This time is enough long to be captured from a GPIO analog or digital input, which reading is once per every 2..3 sec.
Controlling directly connected loads or relays located at a long distance by digital outputs:
AltonaLab has boards with 2 or 8 relays, which can control directly connected loads 12V or if as load is connected the coil of an other relay, then a long distance load can be controlled. For this purpose, supply the board with a power 12V and connect the board to the controlling digital outputs. When the controlling digital output becomes to a high level, 12V appears on its corresponding board connector.
If as load is used a relay board, it has two connectors:
- Relay's coil connector, if is connected to 12V, the relay will be turned ON.
- Normal open contact connector;
Below is shown an example, how to control directly connected load (lamp) and remote controlled load by a single relay board:
