Monday, February 28, 2011

Trying out Fldigi

As previously mentioned, I am a ham nerd. Yep, I like listening to the radio. Morse code? Never touched it. That's alright though, modern technology has removed the requirement for knowing those sorts of things (almost).  For instance, using computers to handle that work for us. Of course someone had to know it to make the software originally. But collaborative works are like that, you each do your part for the greater good.

Enter Fldigi. It's, simply put, a modem that runs off a sound card. It comes with a plethora of operating modes and data rates and allows for very available methods to do digital transmissions using your radio. I will have to point out that the first night I tried this I did not do any transmissions. I just listened in. Locally I found the VOR of our airport sending out it's identifier, tuned in, and watched Fldigi do it's magic.

Some configuration was required but it was trivial. Set the mode to CW, zero'd in on the frequency, and it automagically detected the rate. Then there it was... typing slowly out... my local airport's identifier. Very, very, very cool.

Here's what I needed:
My Yaesu FT-60R
Pryme Hand Mic
Male-Male 3.5mm 3 conductor (stereo) cable
My Computer, running Ubuntu whatever - it's up to date.

Steps to achieve to this:
Turn radio on tune to frequency performing digital transmission (or CW in my case)
Plug hand mic into radio
Plug audio cable into Headphone jack of hand mic
Plug audio cable into aux line in, or Microphone of computer
Install Fldigi: sudo apt-get install fldigi; fldigi &
Go through and configure your options, ignoring PTT for the moment
You should see the waterfall (pretty blue, yellow, orange) flowing at the bottom
Move the Red-box over the band of yellow/orange which looks like morse code
Magic happens.

Presto that's it!

Thursday, January 27, 2011

Modding My Yaesu FT-60R

Yes, I am a Ham Nerd...

The decision to become a ham was a actually made years ago. Though I didn't pursue it then... I've since come to realize that telecommunications are as very important to my life as verbal and non-verbal communication. I spend a lot of time on the Internet and the radio.

Alright, not as much on the radio as other hams. But I do enjoy catching the local nets from time to time. Hearing the other people out there, being able to chit-chat with the locals and the DXers (if I get the opportunity). Get to hear some fascinating things... especially about Medicare and rascal scooters.

So I get it into my head to modify my FT-60R, the reasons are because it should be fairly easy, will exercise some basic de-soldering skills, and these modifications would open up my radio's ability to transmit from 137-174 Mhz and 420-470 Mhz. I'll need to check this per country, but I believe this may come in handy elsewhere (literally). Not to mention, as my friend Bill Wells always said... "Carry an umbrella and it won't rain." In the highly unlikely event it was ever actually needed, it would be available.

In the U.S. as an amateur you may transmit between 144-148Mhz and 420-450 Mhz. Obviously this modification would open me up to the possibility of legal issues in the U.S. if I were not careful. Luckily I am familiar with these specifics so keeping within our little play pin in the U.S. should be no problem what so ever. In fact I keep a reference copy of the ARRL US Amateur Radio Bands on my cell phone for reference (ham nerd, remember?)

Now, the mod... I read someone else's work on this. Originally I read this when I first bought my radio and wasn't sure if I'd actually give it a try. But after watching a bunch of videos on SMT, I thought this may be an excellent way to ease into that sort of thing. The article I followed may be found here.

So this is not a terribly complicated process, in fact it's pretty simple. Just remove 1 resistor. Remove 1 very, very, very small resistor.  Remember when I said it'd be fairly easy, exercising basic de-soldering skills? Well it would have been. If it wasn't for this...

Turns out buying a radio from the reds in China is both cheaper and will come without a band filter. So it would appear my radio already has the ability to transmit at it's highest potential, since it's missing that little resistor and all. A job well... um... easily... um... not done by me at all. But the radio went back together pretty smoothly ^_^ once I remembered to the put the battery clip back on before putting the screws in again.


Wednesday, January 12, 2011

ASCII Experimenter's Coding and Process, Part 1

First blog of the new year, I am excited.

All inventions start with an idea. That idea is grown over time into a design. The design is formalized and then you can start building, prototyping, discovering those things you may have missed and need to be fixed. That's where I am right now, redesigning portions of my little device. Originally I was thinking I could drive whole rows with the 74HC08's. These devices have a maximum current rating of about 25mA, which frankly isn't enough to run 4 x 20mA LEDs simultaneously. I say 4 because the 8 are split across 2 chips. Luckily I can still use them, I just need to be a bit creative.

By arranging my 2 shift registers (74HC164) in a rectangular fashion I can form a grid space of 64 states. Conveniently I have 64 LEDs I may be interested in driving, what providence! Now my 74HC08's can only drive 1 LED at a time each because the Red LEDs in my matrix run at 20 mA and I'd like to maximize this current flow for the effect of viewing the LEDs.

So if I shift in a 1 into both the row and column registers and set the OUT_EN, output enable (which ties into the 74HC08s), HIGH and then the first LED in the corner will turn on. The row register activates the current sinking transistor which will sink the current sourced from the selected 74HC08 pin.

So let's look at how to do this in code. Unfortunately I've skipped the process of designing and watching this code fail (a lot), so I will only be sharing the more decidedly interesting parts of the program in the articles to come. Most of which revolves around getting the data into the chip to begin with. Keeping in mind this is my first ever electronics project of my own design.

Right... code... I assume all I/O has been correctly setup (and I'll show this in the future) for now I'll make a little function called displayMatrix(), void return type and no arguments. Parameters are passed in global memory space (aka the stack). This function also relies on a delay function, which is a small tight loop to add a short delay of a couple of cycles, I'll include this as well:

#define LEDS P1OUT
#define OUT_EN   1
#define ROW_DATA 2
#define ROW_CLK  4
#define COL_DATA 16
#define COL_CLK  32
#define DELAY_TICKS 30

void displayMatrix(void)
        volatile unsigned int row;
        volatile unsigned int col;
        LEDS &= ~(OUT_EN | ROW_DATA | COL_DATA | ROW_CLK | COL_CLK); //Clear data and output enable
        LEDS |= ROW_DATA; //Set row data lines, start at row 1.
        LEDS ^= ROW_CLK; //Clock row data in
        LEDS ^= ROW_CLK;
        LEDS &= ~(ROW_DATA); //Disable row data
        for(row = 0; row < 8; row++) //Rows
                LEDS |= COL_DATA; //Set column data, start at column1.
                LEDS ^= COL_CLK; //Clock column data in
                LEDS ^= COL_CLK;

                LEDS &= ~(COL_DATA); //Disable column data             
                for(col = 8; col > 0; col--)//Columns
                        LEDS |= OUT_EN & (matrix[row] >> (col-1) & 0x01); //Enable output
                        LEDS &= ~(OUT_EN); //Disable output.
                        LEDS ^= COL_CLK; //Next column
                        LEDS ^= COL_CLK;
                LEDS ^= ROW_CLK; //Next row
                LEDS ^= ROW_CLK;
void delay(void)
        volatile unsigned int k;
        k = DELAY_TICKS;

This does have some requirements, for instance due to the nature of the >> and & logic I use, it requires the OUT_EN (P1.0) to be the LSB. All other pins I believe are safe from this restriction and may be moved about at will, as long as you remember to setup the bits in the #define section correctly. Of interesting note, using the TI MSP430- Launchpad I originally used P1.3 for the COL_CLK, this led to a drastically unreliable display.

As it turns out, there is enough noise on this pin when using the launchpad to trigger the 74HC164 clock an extra time or more when transitioning! This noise is caused by a switch attached to that same pin [image to come]. Rather than adding hardware to fix this, I merely avoided it's use, though I do plan on using it with 74HC151 in the future on that pin, but it'll be as an input instead of an output.

This code turns on 1 pixel at a time and splits the entire on time across all 64 pixels, displaying or not. This gives it a uniform brightness which I believe is desirable. My question to everyone else out there.
Can you see a reasonable way to turn 2 LEDs on at the same time (only 1 per 74HC08)?
I have some ideas on how to do this too and I'm willing to spare another pin for a secondary OUT_EN2. Hopefully I'll get some updated schematics up soon too, to assist anyone interested in my design stuff! Thanks :-D