As its being discussed again I thought you might be interested in my work and angle on auto folding mirrors so far, but its not for the fient hearted, and was a project to get my circuit theory back up to scratch as much as anything else.
I wanted auto folding but I wanted to be able to control when the mirrors folded, I don't want them to auto fold every time I lock with the fob. So I've come up with an idea to detect when I press the key fob three times and then it will fold them. Why? Well I thought there might be times when I was just locking for minute or so and in a place where the mirrors could stay open, or on my drive overnight, or if it's icy etc. Not every locking needs the mirrors folded. I went for the option to detect the third press of the key fob, therefore first press is lock, second is deadlock (superlock), now third is retract mirrors. That way I could save a bit of wear and tear on the motors too, no need to have them retracting every time I lock the car.
I also wanted to be sure the logic wouldn't get confused, so I will use a two coil latching relay to control the motors. The benefit of a latching relay being that it remembers its last state and only uses a small amount of current when changing state. I can use this along with the internal door switch and the mirrors won't get mixed up and fold or unfold incorrectly. The logic will always be correct.
Incidentally if you lock the car with one or two presses, ie, either normal or superlocking, then later decide to fold the mirrors, you can at anytime afterwards give three quick presses and the mirrors will fold, it doesn't have to be done at the time you initially lock the car. Unfolding will alway occur when the car is unlocked, if you decided not to fold them when locking, no worries the logic will ensure they stay as they are.
I needed to design the electronics from scratch and the first attempt was made using my knowledge of the 555 timer, I'm a bit rusty in the circuit design these days as its been few years since I've done it, but it got me going and the first effort produced this.
As you can see it triggers on the third pulse so would work, but its clumsy and too complicated. So next I thought about an ****ogue solution, just to see how that would work and came up with this.
It kind of works, is simple enough but requires precise timed pulses (ie regularly fixed key fob presses), which in practise wouldn't be the case. I wanted it to detect 3 presses of the key fob from around 3 secs up to around 12 secs, (ie 3 quick presses to 3 fairly slow presses), to make it flexible enough in the real world and this circuit isn't reliable enough to do that, but it led me to realise a digital solution was needed. The third attempt was a digital circuit then.
This circuit is one that would fit the bill nicely, but I wasn't fully happy with its behaviour, so I scrapped that one too, because I knew now a more elegant circuit was needed. After a bit of reworking using a counter and a NAND gate the final solution then that I am happy with is this.
This circuit detects the third press of the key fob and changes the state of the NAND gate to activate the first coil on the relay to open the contacts to fold the mirrors. The waveform shown in the simulation shows the key fob presses in green, and the relay switching in cyan. The other waveforms are just to show how the circuit works in more detail.The relay contacts will be wired in series with the exiting circuit of the door switch, then the door switch will operate as normal and the logic of folding/unfolding will be preserved. I'll need to ensure power is available when the ignition is off, but don't see a problem with that, current is microamps for these CMOS chips. Though a little rewiring will be needed I'd prefer to do that and preserve the operation of the door folding switch.
Upon unlocking the unlock pulse will activate the second coil in the latching relay resetting it to unfold the mirrors. If they are already unfolded nothing will happen.
So in theory I have a circuit, theory is all well and good, but before producing a circuit board some testing is needed. The next step then was to breadboard it and here it is.
You can clearly see the two ICs, a few discreet components, and the dual coil latching relay. Don't be put off by the way it looks at this stage, this is how bread boarding works. The main thing now is to power it up and see if the theory transfers into practise. I'm happy to say so far so good, it works. The relay switches over every time I give it three pulses within 5 seconds, no false triggering occurred and no unexpected behaviour. As much as I could test it, it gave 100% reliability.
The final circuit board looks better than the breadboard.
Well the 3d mode does, and it will do once made up. I've made plenty of custom copper circuit boards so I'm not concerned about this stage when I get around to it.
And thats as far as I've got so far. Too much else going on just now, though I hope to pick this project up at some stage to finish it off. The idea was to encapsulate the circuit board in a resin block with a socket attached, then a pre wired plug which would have just 5 wires, ground, +12v, lock, unlock, and fold (unfold), to be spliced into the loom under the drivers side kick panel.
I thought I'd share it with you as the topic comes up every now and then, and my angle on how it should work might be of interest. i know its not finished, but once I get some spare time I hope to get it installed.
I wanted auto folding but I wanted to be able to control when the mirrors folded, I don't want them to auto fold every time I lock with the fob. So I've come up with an idea to detect when I press the key fob three times and then it will fold them. Why? Well I thought there might be times when I was just locking for minute or so and in a place where the mirrors could stay open, or on my drive overnight, or if it's icy etc. Not every locking needs the mirrors folded. I went for the option to detect the third press of the key fob, therefore first press is lock, second is deadlock (superlock), now third is retract mirrors. That way I could save a bit of wear and tear on the motors too, no need to have them retracting every time I lock the car.
I also wanted to be sure the logic wouldn't get confused, so I will use a two coil latching relay to control the motors. The benefit of a latching relay being that it remembers its last state and only uses a small amount of current when changing state. I can use this along with the internal door switch and the mirrors won't get mixed up and fold or unfold incorrectly. The logic will always be correct.
Incidentally if you lock the car with one or two presses, ie, either normal or superlocking, then later decide to fold the mirrors, you can at anytime afterwards give three quick presses and the mirrors will fold, it doesn't have to be done at the time you initially lock the car. Unfolding will alway occur when the car is unlocked, if you decided not to fold them when locking, no worries the logic will ensure they stay as they are.
I needed to design the electronics from scratch and the first attempt was made using my knowledge of the 555 timer, I'm a bit rusty in the circuit design these days as its been few years since I've done it, but it got me going and the first effort produced this.
As you can see it triggers on the third pulse so would work, but its clumsy and too complicated. So next I thought about an ****ogue solution, just to see how that would work and came up with this.
It kind of works, is simple enough but requires precise timed pulses (ie regularly fixed key fob presses), which in practise wouldn't be the case. I wanted it to detect 3 presses of the key fob from around 3 secs up to around 12 secs, (ie 3 quick presses to 3 fairly slow presses), to make it flexible enough in the real world and this circuit isn't reliable enough to do that, but it led me to realise a digital solution was needed. The third attempt was a digital circuit then.
This circuit is one that would fit the bill nicely, but I wasn't fully happy with its behaviour, so I scrapped that one too, because I knew now a more elegant circuit was needed. After a bit of reworking using a counter and a NAND gate the final solution then that I am happy with is this.
This circuit detects the third press of the key fob and changes the state of the NAND gate to activate the first coil on the relay to open the contacts to fold the mirrors. The waveform shown in the simulation shows the key fob presses in green, and the relay switching in cyan. The other waveforms are just to show how the circuit works in more detail.The relay contacts will be wired in series with the exiting circuit of the door switch, then the door switch will operate as normal and the logic of folding/unfolding will be preserved. I'll need to ensure power is available when the ignition is off, but don't see a problem with that, current is microamps for these CMOS chips. Though a little rewiring will be needed I'd prefer to do that and preserve the operation of the door folding switch.
Upon unlocking the unlock pulse will activate the second coil in the latching relay resetting it to unfold the mirrors. If they are already unfolded nothing will happen.
So in theory I have a circuit, theory is all well and good, but before producing a circuit board some testing is needed. The next step then was to breadboard it and here it is.
You can clearly see the two ICs, a few discreet components, and the dual coil latching relay. Don't be put off by the way it looks at this stage, this is how bread boarding works. The main thing now is to power it up and see if the theory transfers into practise. I'm happy to say so far so good, it works. The relay switches over every time I give it three pulses within 5 seconds, no false triggering occurred and no unexpected behaviour. As much as I could test it, it gave 100% reliability.
The final circuit board looks better than the breadboard.
Well the 3d mode does, and it will do once made up. I've made plenty of custom copper circuit boards so I'm not concerned about this stage when I get around to it.
And thats as far as I've got so far. Too much else going on just now, though I hope to pick this project up at some stage to finish it off. The idea was to encapsulate the circuit board in a resin block with a socket attached, then a pre wired plug which would have just 5 wires, ground, +12v, lock, unlock, and fold (unfold), to be spliced into the loom under the drivers side kick panel.
I thought I'd share it with you as the topic comes up every now and then, and my angle on how it should work might be of interest. i know its not finished, but once I get some spare time I hope to get it installed.
