Nerd out to play

Adding vias to a KiCAD board without stitching

I’ve been working with KiCAD  as my main schematic capturer and PCB layout software for a while now.

One thing with this nice and free software I wasn’t pleased with, is that I was unable to add a via with adding a track to it’s placement. I have been stitching for all those ground vias I’ve been doing so far.
But that suddenly changed when a Chris over at launchpad for KiCAD told me that I could just do a simple footprint, with the via settings , i.e. the drill size, diameter, clearance settings, and last but most important: Net name.

This was brilliant, as I do a lot of two-layer boards where I pour GND for all the ground connections.

But when trying to name a new modules net name to GND, pcbnew told me that it was unable to name because it couldn’t find the net.

via_unnamed

 

 

 

 

 

This was fixed by saving the module without net or pin number, then inserting the module into a board with the correct netname in use,
renamed the netname of the via to GND or any other, and then opening the module in the editor, saving it, as the name appeared on the via.
This was a very nice fix, because I can now easily insert vias all over the board to connect the grounds, using hotkey “O”, and find the correct module.

naming_via  Via_GND_Named

 

 

 

 

 

This is an easy fix, if you were trying to go from Eagle to KiCAD, which is a free, nice, open-source alternative.

Lerche

Pinguino board

I’ve started using KiCAD for PCB designing about 2 weeks ago.
It has been somewhat weird going from Eagle to KiCAD, but it’s a good alternative and I really like the 3D function in pcbnew.

That being said, I have designed a board for PIC18F47J53, the same MCU which will be used in the new Pinguino board .

The PCB will fit in normal mbed designs (almost), only difference is that the mbed has 2×20 pin header, the one I designed is only 2×17 pins.
The reason is that I would like to have PIC based board, as I have loads of mbed’s, arduino’s, and also a BIG development board for PICs,
but I really like to be able to develop without the board making a mess around my desk, as well as on a PIC.

The board is a two layer, will probably be blue, red or black (haven’t decided yet).
It will look something like this:

Pinguino_nano_47J53_front Pinguino_nano_47J53

 

 

 

 

 

I’m still going over the design improving the tracks, vias and so on, but as soon as I have it, tested it, and done a simple design, I will do another post.

Be good!

Lerche

Connection fault on SIM900

I’ve been working on a PCB in around 2 years now, a lot has changed through that time, starting with a PIC, went on to a mbed LPC1768, and recently I moved to the mbed LPC11U24, because is can be had in a TQFP48.

This sucker runs at 48 MHz and calculates in 32 bit. Nice.

The board I designed contains all the necessary stuff to make the SIM900 work. DC/DC converter, simcard holder, some LEDs and before I changed it, I used N-channel FETs to translate voltages to the LPC11U24. It has now changed to a simple resistor divider. Through the ARM I’m running relays controlled through sms, which also can be used as inputs, as the common pins on the relays is connected through a current limiting resistor and a zener diode to the ARM.

I have only got small C/C++ experience, but the software is about to get finished.

Right now I’m able to store commands to turn on and off relays, read temperature and read the status of the module. The only thing I’m missing is to be able to track the module with a sms, using triangulation from SIM900.

But that’s being debugged right now.

Why I’m writing is that I had a problem where SIM900 couldn’t connect to the GSM network after I had issued AT+SAPBR=1,1 command. I had to hard reset the module, due to an error. After this it wouldn’t connect at all. This was easily fixed by removing the simcard, booting the module, powering it down and refitting the simcard. Works like a charm!!

 

I’ll post an image when I’ve got one.

EDIT: Picture of the boards I deasigned so far:

SIM900 Board1 SIM900 Boards2

 

 

 

 

 

Click on it to make it larger.

Happy electronicking!!

Making hydrogen in smaller portions

I always liked to design/make things smaller than they originally are.
This is why I made this Water splitting cell, in a ear-drops container.

The cell consists of two stainless steel rods, pushed throught the side of the container,
with a screw terminal connected to them.
On the terminal, a pair of wires a soldered, making it easy to connect to a powersupply.

Tiny Water Splitting Cell

 

 

 

 

 

 

 

 

 

The coin is a danish 5DKK, it has a diameter of 28,4 MM (1.12 inches).

After adding the water and a couple of drops of NaOH, the cell was almost filled to the top.
Connecting power to the cell, at 12V it draws around 1.5Amps.

I haven’t got a build guide, but whenever my ears have a defect again, I’ll do another, to show you how it’s done.

A video to show that it’s real:

Always remember safety when you do things like this.

I’m not responsable for any damage to you or you equipment.

Making hydrogen

One of the things I find interesting and have found interesting since school, is hydrogen.

This simple atom can be real fun to do stuff with.
One thing that is always interesting is make something that goes boom.
In my case, I replicated a water splitting unit, just for the fun and the bang.

Source (In danish)

I had an old computer powersupply laying in my junk box, and this fits the job perfect,
as I needed around 12V with enough current to make suffecient hydrogen and oxygen.

A picture of the setup:

Hydrogen Oxygen splitting setup

 

 

 

 

 

 

 

 

SAFETY FIRST:
Goggles in the lower left corner, those will be weared as soon as I turn on the powersupply, just to make sure nothing happens to my eyes.
And of course also when I light the bubbles.

The setup is a single computer powersupply, where the 12V output was connected directly across the stainless steel bicycle spokes.
A 5 mm rubber tubing hotglued to the top of the bottle lid, running down to a container with soap water.
In the cell itself, just plain tap water, but added a bit of NaOH (Toilet cleaner, or whatever you call it), 30 mL or so.

WHEN YOU HANDLE CHEMICALS, MAKE SURE TO WEAR GLOVES AND GOGGLES!! Also, a good ventilated area is a nice thing to work in with these thing.

A short video demonstrating the “purpose” of the  setup:

Always remember safety when you do things like this.

I’m not responsable for any damage to you or you equipment.

HobbyKing SS series 18A ESC.

As I bought the ESC’s for my TriCopter I was thinking that no matter what,
it should be able to drive the DT750 good enough, with or without updated firmware.
With this in mind, I bought the HobbyKing SS 18A ESC.

HobbyKing SS 18A

 

 

 

 

 

 

 

If you look closely the sticker indicating battery and output ports a reversed 😉

This was probably a good idea, they’re cheap, can be programmed with a Turnigy program card,
and when I received the ESC’s, I was that they were fitted with the ATmega48 MCU.
This is nice, as I own a USBasp, so the new firmware for those can easily be programmed to those.
BUT: Some of these boards have their nRESET pin disconnected through the fuse bits.
I haven’t tested it though, as I still need some of the parts, to build the entire copter and then testing the settings
by the programming card.

Instead let’s look at the FETs onboard these things:

P/N FETs of HK SS 18A

 

 

 

 

 

 

 

The SO-8 chips are soldered on in pairs, not very nice work, but the solderblobs between the pins are okay, as they’re connected to the same spot on the PCB.
The P-FETs are Si4425, -30V -11.4A@Vgs= -10V.
The N-FETs are Si4856,  30V 17A@Vgs= 10V.

One thing I noticed was the one of the boards was fitted with the A1730 P-FETs.
These are -30V -6.5A@Vgs= -10V.
Those FETs will probably do fine, but I really don’t like the idea of just replacing one part with any other.

The FETs are chilled with a layer heat-transporting goo of some sort, it’s black, and sticks a bit to the FETs.
On top of this is a aluminum plate, just pressed on to this:

FET Chiller

 

 

 

 

 

 

 

 

The topside, confirming the ATmega48 chip, as well as the programming pins:

HK SS 18A ATmega48

 

 

 

 

 

 

 

 

Left side to right:
7805 – 5V voltage regulators, SO-8 on top is another 5V regulator,
a bunch of resistors, some transistors and of course the ATmega48.
The programming pins on the right is like this from the top:
nRESET – Pulled up to Vcc by 4k7 resistor.
VCC – +5V
GND – 0V
SCK – Clock for SPI interface
MISO – Input for SPI data
MOSI – Output for SPI data

I don’t now what my idea with this post was, other than inform you about the product from HobbyKing.

I’m not responsable for any damage to you or your equipment.

Forgot the trainer cable for HK-T6A transmitter?

Yeah, that’s what I did.

Found a guide here, followed it and modified a bit.

Fortunately I have a bunch of CP2102 USB to Serial converters laying around.
I simply soldered wires on the board directly, but soldered the wires on pinheaders to be able to remove
the wires from the trainer port of the HK-T6A transmitter.
Remember when you plug in the CP2102 the drivers may have to install first.

CP2102 - USB to Serial converter

 

 

 

 

 

 

 

 

 

From there just ran to wires about 3 feet, so I’m able to adjust without placing the transmitter in front of the PC monitor,
adding the pinheaders to the wires.

Pinheader CP2102 trainer cable

 

 

 

 

 

 

 

 

When removing the header from the trainer port, the header (which consists of two row), moved from each other.
As I were epoxy-fying my DT750 motors, I just pushed in the headers, and put a little expy between them and around the wires.
This will hold it nicely together, making it easier to connect the trainer port.

CP2102 connected to trainer port of HK-T6A transmitter

 

 

 

 

 

 

 

 

Tested with this software. It works like a charm!
Now I’m able to reverse the channels.

I’m not responsable for any damage to you or you equipment.

Tricopter build series

Looong time since I’ve been here.

But now let’s try it again.

I’m going to build a Tricopter, based on rcexplorer’s guide.
First of, it needs a frame. As I am the lazy kind, I bought the frame from rcexplorer’s site.

I ordered the frame set and got an e-mail confirming this from him in person.
The frame itself is perfectly cut, putting them on top of each other confirms that now slop was involved in the cutting proces.
The frame was sent through the post office, at friday and got here monday. (I live in Denmark, not far from Sweden).

RCexplorer Tripcopter Frame

I ordered all the electronics from HobbyKing, including a VERY cheap Transmitter/Receiver pair.
A complete list of the components will be written in this blog, once the build is complete.

I bought the pinewood in a shop called Bauhaus, they had it for around 1.5$ for 90 CM.
Two of those, cut in 40 CM length for arms, and drilled a hole in two of them, for the frame mount.

Next is to assemble the frame and pinewood.

That’s all.

 

CP2102 and Arduino

I needed a USB to RS232 (TTL), converter.
I bought one of those cheap Ebay CP2102 converters, and tried using it.
But the RST pin on the connector is Reset for the CP2102 chip.

This wasn’t the idea, as I needed to connect it directly to on of my boards.
So hacking it was one of my choices, which i did:

I started by cutting the trace for the RST pin on the back of the board, and solder a wire from the connector to the switch:

 

Next step was to cut the trace for the unused DSR on the top side of the board:

 

As you can see, the switch is able to connect either the DTR or the RTS to the output pin.

The switch I used was from RS, one I just had laying around.
RS: 204-7871

Testing:
Well, whattayaknow,  it works.

Maybe some of you can use this, but I’m not responsible for any damage to you or your goods.
Lerche

Getting the Arduino IDE to work with ATtiny85

So….
I’ve been having troubles with the Arduino IDE, Duemilanove, and UNO.

First of, the UNO doesn’t seem to be able to be used as ISP, and that’s about what I found out.
Well, I bought a Duemilanove, as I know those work, Fantastic!!
BUT: When installing the files for ATtiny85 compiling, at Arduino IDE v.1, uploading the ArduinoISP, and trying to upload
blink to ATtiny85, it kept failing on me.
Hmm… The interwebs seems to have loads of solutions, but I didn’t want to do hardware, as I bought a product, I expect to work.
It then came to my mind:
The ArduinoISP from Ver. 0022 uploadet to Duemilanove, but using the v 1 to upload software to ATtiny85.

Arduino IDE 0022 -> ArduinoISP -> Arduino Duemilanove.
Arduino IDE 1 -> Blink example -> ATtiny85 (Either 1 or 8 MHz, but remember to upload bootloader if using 8 MHz)

Simple? No. Works? Yes!

That’s all for tonight.

Lerche

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