Yes these are steps you feel when turning the knobs and are in fact rotary encoders. For me what I'm looking to do is what you've described in your second option.
I understand creating a multiplexed interface. I happen to work as an automotive tech and see this kind of circuitry in speed control, steering control, and ignition switches often. I really want to learn and understand the operation of the FB and your add-on module. I guess I thought a DAC existed that would output variable voltages (within 0-5V), which would really simplify this task. Maybe it does exist.
Now that I understand how the rotary part can be accomplished, there are a couple momentary on/off switches that would need to be taken care of and also monitoring the status of them. I imagine for monitoring LED status of these switches, a digital input on the FB could be used to sense voltage present. Would it work to tap into the feed of the LED (anode side)?
Also, I had never heard of the I2C Bus, very impressive. The ability to run a BUS network hugely increases simplicity and physical circuits when adding devices (nodes). I guess in this application the limiting factor would be the main processor? Creating input sensors based on 5V and having the ability to BUS the information, well, that's exciting.
For myself, I'd like to take PC control of the HVAC further and possibly using the BUS system create and AUTO HVAC system with infrared temperature, humidity, and sun load load sensors.
I have only one criticism, and that's the on-board connectors. I would like to have seen something like this..HERE Wouldn't this allow connector/harnesses to be fabricated much more easily? I think the FB and your add-on eyeR interceptor are great products with huge almost endless application.
Thanks for you help. I look forward to learning more.
You were saying that the rotary part was accomplished? I assume you are using some kind of interface for the encoders as it is not yet posible to connect an encoder directly to the FB and get the PC to sample it fast enough. There is a thread somewhere discussing rotary encoders with the FB, but im not sure if there was a solution yet.
The eyeR doesnt support rotary encoders yet, BUT.... there are some outputs that can be used as inputs, so with some software it would be possible to do hi-speed rotary encoder detection. Though I have to think about this for a bit.
With connecting the FB to LEDs, this part is simpler.
The easiest way to test this is:
1. Grab you multimeter (20v DC range) and connect the black lead to GND (negative)
2. Put the RED lead on one side of the led, record the voltage. Press the button then record the voltage again.
3. Repeat this test with the RED lead on the other side of the LED.
You will notice that one of the 2 combinations will show you a difference in voltage when the button is pressed and released. If you two voltage readings are less than 5v say no more than 4v, then you can connect this point directly to the FB analog input. If these voltages are about 12v then you will need a voltage divider before you connect it to the brain.
With the connectors, I was initally going to use tiny SMD type connectors but then special cable had to be made up, hence a greater cost. The reason why I used a 32pin header was because its really easy to add relays and connect your servo and PWM connectors. Though the main reason is that you can connect a readilly availiable and cost effective 32pin ribbon cable (similar to those IDE hard disks) right on the entire connector strip. This is real handy if your making custom modules that connect to the eyeR.
These are easy to get, cost effective and making up a custom length is a piece of cake.
No I haven't accomplished any of project yet. Just been thinking about the I2C Bus onboard. What would it take to get the software up to speed to take advantage of this? Cause adding a I2C compatible digital potentiometer would eliminate the need to create a multiplex interface, wouldn't it?
I have been looking at a few "I2C" digital potentiometers, and I found that most single ones claim to have a "simple I2C interface" have a look at here if your interested. What does "simple" mean, well in fact its not the traditional I2C bus protocol. This means that you cant daisy chain a bunch of these together. After looking at the specs, I found its quite simple to implement a simple and high sampling rate decoder, just 2 pins are required. If you really want you can use the standard I2C you will have to wait a bit for the software, also the sampling wont be as fast.
Originally Posted by NitroLarry
A digital pot with the traditional I2C interface can be found here.
One question, what is the digital pot going to control, if your reading in the encoder inputs from the dials, then you would also want encoded outputs to go back to the encoder dials. Hence the digital pot is not required.
I hope I have been of assistance here.
If it looks like there is something missing from thread its because the first post was re-located to HERE. Don't worry, It took me a while to realize it was missing and moved
So any new posts should be added to the new link.
Your new Dual PWM FET driver looks real cool! Its listed to have a 20A continuous rating. It's been a long time since I clamped a blower motor, but almost all are protected by a 40A fuse. What maximum rating do you see this add-on handling?
I happen to live in Canada and often see blower motor resistor failures where the amp draw blows the thermal fuse on speeds of 1-3 of a 4 speed dial. So no where near full draw cause only position 4 is full 12 volts.
The thought of having a 15 or more blower motor settings is really exciting. The perfect speed can be achieved.
Originally Posted by NitroLarry
You will find that if there is a 40A fuse the operating current of the blower would be ~half that. A bit of slack is left due to the initial inrush current of the blower starting up.
From the 4 vehicles I tested it on, the maximum Blower current I found was 18A. If you have the FB current meter you could use that to test what yours draws, else you you need a high current meter.
The Fet Driver can easily handle a 40A surge which would be enough to blow the fuse. As it stands the Fet Driver can actually handle 25A continuous.
About the resistors there inefficient and get really hot! With this unit you just have to connect it to the highest position of your blower setting which would be 12v.i.e bypassing the resistors
Frequency measurement is here!
A frequency measurement firmware upgrade is now available for the eyeR, see first post for details.