Project: Remoteli – Finished

It’s been a long project. I think this is due to a combination of factors – a large number of manufactured parts, fiddly soldering and software troubles. Certainly at times I have struggled to find time to work on it, worsened by spending the year studying in America rather than the UK. Getting back into the project after waiting two weeks for a board to arrive was a challenge I faced more than once.

Nonetheless, Remoteli is now complete! (At just 39x18x4mm ignoring nuts and bolts)

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Project: Remoteli – Plastic Spacer

Remoteli’s construction will be a PCB (the one I already have with all of the buttons on it), a plastic layer which is 1.6mm thick, and another PCB on top to cover all of the electronics, except for the switch, IR receiver and transmitter, and the buttons.

Today I finally managed to hunt down a 3D printer in order to print out the plastic spacer. Here are my designs:

It turned out a friend of a friend had a 3D printer I could use.

Being a small model, it only took 12 minutes to print and it came out pretty well. Unfortunately the detail around the screw holes and the top of the circle didn’t print well, but it was good enough to work. I didn’t really expect it all of come out perfectly anyway.

Here it is:

spacer and board

I was impressed how well the battery fit into the spacer. Now I am just waiting for the second board to arrive from OSH Park.

Project: Remoteli – Circuit Board Second Version

After some preliminary testing of the first version of the circuit boards, I found that they were pretty horrible for developing on. The reason for this is the programming connections.

To program the microcontroller, I use an AVRISP MKII programmer. These programmers use an SPI protocol to talk to the chip, so it requires a VCC, GND, MOSI, MISO, SCK and RESET connections. In the initial version of the board I made these connections by soldering wires to pads on the board and then connecting crocodile clips to these wires.

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As you can see, this got a bit messy and the wires kept threatening to break off. In fact, I also, embarrassingly, forgot to leave a pad to connect to the RESET line and so I had to precariously solder this wire onto the board which kept breaking.

This wasn’t the way I wanted to continue with these boards, it was stressful and took too long to set up. So I redid the boards and had them made again. Luckily this only costs $5.50, but unfortunately it also takes about 12 days, so it isn’t something I want to keep doing, but I’ve definitely learnt a lesson.

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The new version of the boards includes 6 copper pads where I can connect crocodile clips directly. This allows me to entirely the remove the programmer when I want to and doesn’t have any of those difficult wires. It also has proper silkscreening, and I’ve managed to solder on the IR receiver!

I’ve tested it out and it works nicely. I’m very happy with it.

 

Project: Remoteli – IR Receiver

Today I wanted to test out the infrared receiver. This is the datasheet. It’s got an internal 38kHz frequency filter so that it specifically picks up signals from a tv remote.

I decided to test it before mounting it to the board by soldering wires to it and measuring the signals. But it’s only 3.95×3.95mm large! After a lot of messing around with a soldering iron, I eventually had this.

The small shiny bit of plastic is where the light enters the chip

The small shiny bit of plastic is where the light enters the chip

I connected up a 3.3V power supply and put my oscilloscope on the output. The output looked identical to the signals from the IR receiver in my Infra-red Repeater Mini-project, so it looks like it’ll be just fine for this project.

Project: Remoteli – Bottom board

For this project, I’ve decided to start using Altium’s Circuit Maker, rather than Eagle, to design my PCBs. The main reason for this is because Circuit Maker is very similar to Altium Designer which is a professional-level package (and the price reflects it) so it’d be useful to be able to use it. Circuit Maker also has a very nice 3D view mode:

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