more for self notes than anything

I moved into a new apartment on August, and so far, it's been great.

One of the things that I noticed when I got the keys to the apartment was that the front-door key was labeled "do not duplicate."

I normally copied a set of keys just in case I lose them, so I checked the internet to see if the "do not duplicate" denoted a physical difficulty or a moral request. The results pointed towards the former. Search results pointed out that these keys required a special "owner card," and locksmiths needed a special copying device for these specific locks. Inconvenient.

Meanwhile, I was humoring the thought of getting my hands on a Raspberry Pi, but I couldn't really think of a reason to justify the purchase.

Well, the two thoughts crossed ways, and the conclusion of "I should program something to open my front door" was made.

How?

There's an intercom system in the apartment, and I supposed that having something press the door open button would be something.

And the click on the check out button was made.

That was about 2 weeks ago.The Raspberry Pi is now here, and I have already started messing around with it.

After working on it a bit, doing research on implementation and "learning" Python whenever it is needed, I thought that recording my progress would be a good and organized way to look back on it.

This is that record, and I'll try to write as much information as I can.

Couple of posts would be a recap of my progress to date, and future posts will be more of an update.

Comments

finally got around to it (nrf24l0+ and servo)

On a previous post , I used the nrf24l01+ wireless chip to communicate between the Raspberry Pi and an Arduino, but only got lights to turn on. I remember being confused as to why servos would not work, and somewhat left it there. I started messing around with it again, and I am concluding that it might have been just a power issue. Here is the servo moving properly: The Arduino is on the ground due to the short length of the wires powering them. Just as a recap, what is happening is: - a C++ program using the RF24 library is compiled in the Raspberry Pi (connected to an nrf24l01+ chip) to broadcast a message. When executed, it will broadcast the message. - the Arduino (connected to another nrf24l01+ chip) programmed to receive messages receives the message, and upon receipt sends a signal to an Arduino that is wired to the servo to move the servo. Two separate Arduinos are used, as it seems that the servo library and the RF24 library do not seem to run properly toget...

alcohol sensor (and some patience)

Soldered the alcohol sensor into something that is connectable: I tried to connect this to the Arduino, as I had the appropriate circuitry, but I did not get any legitimate output from it. 5V going in, 5V coming out with no variations. Nothing seems to be awry in wiring, as the circuit seems to be grounded properly (and the 5V current is flowing). There are a couple of potential factors as to why I'm not seeing any results: - I'm using a 10k ohm resistor, while some guides (and the datasheet for the sensor) asks for 100-200k. However, there seems to be a good amount of people using 10k and getting at least some kind of result. A batch of 100k ohm resistors I ordered is on its way, so I guess I can try with them when they come. - This site claims that these sensors take 24-48 hours for its signals to be stable. It also tells me that I should not be powering the sensor directly from the Arduino, which I have been doing, out of concern that the power draw of ...

how the fingers work

the fingers are moved using wires and tension. each finger is looped through with a wire/string/line in a top-bottom fashion. when the top wire is loosened/bottom wire is tightened, the finger curls in its joints, resulting in a "bent finger". you don't have precise control of each joint movement, but it is simple enough to be controlled by a single actuator (in this case a servo). here is me just using my own hands as an actuator: here it is hooked up to as servo and controlled by a potentiometer: the movement is not smooth because 1) it's controlled by a potentiometer that I am controlling, as seen in the background, and I was unable to move it all the way with one smooth finer motion. 2) the tension in the line was not entirely tight. I need to learn how to tie these well. now I have a get a bunch of servos. much credit and thanks to Inmoov once again.

the quest for robots

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