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Hygrometer to ioBridge?

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Nrets

New Member
Hey guys!

I've reccently purchased an iobridge module along with a I/O input module for my own components in addition a temperature sensor. However, I also need to log humidity data, and finding hygrometer sensors seems to be a lot more difficult than finding temperature sensors.

I came across a post on this forum that linked to a parallax component:
Sensirion Temperature/Humidity Sensor
Kind of expensive but it seems to do the job.

Could this component be linked directly to an I/O module for the ioBridge? Or do I need to build a circuit to interface with the sensor? If it requires a microcontroller for any reason, I am fine with that as long as it can be handled through a PIC.
 

Nrets

New Member
Ok I'll keep searching.

The output from the device I linked to is digital serial, so I imagine I could not use simple I/O into the ioBridge. I'd probably have to have a digital input device interfacing between the two?

something like the "Serial Smart Board"?
ioBridge | Store

I don't know it's a simple matter to convert digital serial data to analog, and if so, if it can be done for under 20 dollars.
 

Nrets

New Member
That's a very nice website! It is unfortunate I didn't come across that sooner.

On the other hand, digikey (for example) has a $15 sensor:
HIH-4030/31 Humidity Sensor

With analog output 0-5v. The inputs to the ioBridge accepts analog input on pin 1. Alternatively it accepts digital input on pin 2. Power is pins 4 and 5 and pin 3 is for digital output.
http://www.electro-tech-online.com/custompdfs/2009/03/IO-204_manual.pdf

So to me, it seems I need absolutely no interface between the HIH-4030 sensor and the ioBridge, correct? Or should I have a board for safety reasons/amplification?

I could also use the parallax sensor with the digital input...(2 pin in/out serial data)

EDIT: The data sheet for the HIH-4030 has an example circuit with an 80kOhm resistor between the output and ground, is this a pull down resistor?
 
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3v0

Coop Build Coordinator
Forum Supporter
Let me start by saying most of the people here would start with a microcontroller and program it to what they needed to do.

The sensor on anderson's site is interfaced to a dallas 1 wire network so its price should not be compared to an analog output sensor.

The ioBridge has a analog input and the sensor has an analog output. As long as the output range of the sensor falls within the input range of the iobridge you are OK. The sensor is 0-5V check the iobridge but I would assume it is the same or maybe greater.

The resistor is shown to indicated there must be a reistance of at least 80 ohms between the analog input pin on the iobridge and and ground. The analog will be high impedance so you do not have to use the resistor.

There are two clues that tell you it is not a pull down resistor. First the output is analog. A pullup or down resistor is only used on digital signals. (at least I have never seen it done with analog signals).
80 ohms would be a bad choice for a pull down resistor because it would draw a lot of current. I=V/R = 5/80 - 0.075Amp or 75ma. Values like 4.7K or 10K are common.

And welcome to the forum :)
 

Nrets

New Member
Let me start by saying most of the people here would start with a microcontroller and program it to what they needed to do.
Well I was originally planning on making a data logger with a PIC, but I ran into a lot of issues this way. The PIC would be responsible for reading data from multiple sensors and logging it somehow either to some external memory or sending it through a serial port to be logged on a computer. But both methods require more circuitry that I am not familiar with. Then there's the code for the PIC. I'm pretty new to assembly and I am 100% confident that it would take me weeks of debugging before I got anything working at all. I thought it was a bit too ambitous for a first project.

Then I heard about the ioBridge. The great thing about the module is that it connects directly to my router, meaning I don't need a dedicated computer to log data. I'm MUCH more comfortable with web-based languages like PHP anyways. I feel pretty confident that I can setup data logging online very easily with this module. At the same time it doesn't take away from the freedom of building your own circuits. The ioBridge company only offers a few input devices, so most of them will be built by myself.

There are two clues that tell you it is not a pull down resistor. First the output is analog.
Haha, I'm an idiot.

I suppose I could make a PIC circuit that would accept something like 8 inputs, convert everything to a digitial signal, then send the bits to the ioBridge in a series. Then I can decode the signal on the software side of things. That way I can have 8 inputs on 1 channel or something. I don't really know how much flexibility I have with reading what exits the ioBridge, it should be arriving this week, so I'll fool around with things and get comfortable.
 

3v0

Coop Build Coordinator
Forum Supporter
We all start from a position that is comfortable to us.

There is nothing wrong with the path you have taken. You do not need to use a microcontroller with the iobridge. It has 8 input ports and each has an analog input that should connect directly to the humidity sensor we talked about.
Each I/O channel’s analog input pin is connected to a 10-bit analog-to-digital
converter. The voltage input range is 0V to +5V. An input above +5V or below
0V could damage the module and should be avoided.
It looks like you are set. :D

If you do want to come play in our sandbox you are welcome. In the past few years the cost of good tools have plumeted. A PIC programmer/(real time debugger with breakpoints etc) can be had for $50 or less. Many of the chips have internal clocks so you do not even need a crystal. Five wires from the programmer to the chip, add a bypass cap and you are up and running.

There is no need to code in assembly. Much of the embedded work is done in C. Microchip even provides a free student version (non commerical) compiler. 18F family.

If you want to learn to program microcontrolers then start with blinking a LED. We all did that and we will be here to help.

3v0

3v0
 

Nrets

New Member
The problem with your "old power supplies" is that they don't offer more than 12V outputs and thus your only going to be able to run any tecs you buy at half their power ratings.
I own a USB PIC programmer and have 4 16F628A's I've been using for experimentation. I've made a variety of simple LED circuits and another to multiplex 4 7-segment LEDs, that went OK, had a lot of problems getting it to work though. I don't have a debugger or anything, so finding out where the problem is can be VERY annoying.

My plan with the 16F628A is to connect to 2 40 pin shift/latch chips and multiplex 64 tiny SMD LEDs, then spin this with a harddrive to create a POV display. I already have the MATLAB code that converts images into the necessary radial bits for the LEDs, but the circuit has not been started (I have it drawn up, that's all), nor has the program.

Anyways, I'm diverging. Yes, the ioBridge has 8 inputs total, but I was just seeing if it was possible to send data from 8 devices into a single ioBridge input coherently?
 

3v0

Coop Build Coordinator
Forum Supporter
Anyways, I'm diverging. Yes, the ioBridge has 8 inputs total, but I was just seeing if it was possible to send data from 8 devices into a single ioBridge input coherently?
It should work.

You would be much happier program in C with an programmer that has an in-circuit debugger.

Regarding the POV. I teach embedded systems to high school students. One of the things I wanted to do was POV but I did not come up with a solution that the kids could build and take home. Currently we are building LED cubes.
 

Nrets

New Member
I received the ioBridge several days ago but have not had any time to play around with it much. It works though. I would like to purchase the hygrometer from digikey, because it can be directly hooked up to an analog input, but I know I need other things from them for my POV project and want to order everything at once. I should also figure out the circuit for combine 8 inputs into one digital output so I can order those parts also.

I posted a thread in the Microcontroller forum a long time ago about the POV project:
http://www.electro-tech-online.com/threads/pov-smd-led-array-with-pic-beginner.86677/

And the circuit ended up being:
POVpreliminary3.png

I have all the parts but haven't done any work on the project yet. I'm trying to start small with the code because I know that will be my biggest hurtle. I'll update that thread this weekend.
 

3v0

Coop Build Coordinator
Forum Supporter
I should also figure out the circuit for combine 8 inputs into one digital output so I can order those parts also.
I am not sure what you are saying. If you are talking about hooking up the humidity sensors it should be easy.
The ioBridge has 8 or 10 I/O ports. Each I/O port has an analog input. Hook one humidity sensor to the analog input of each port.
 
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