wwward.expressions

Simple Serial Display How To

Simple Serial Display

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Parts Required:

1. Arduino Mini USB Adapter*
   makershed.com part number MKSP3 approximately $20
2. Serial Enabled 16x2 LCD - Red on Black 5V**
   sparkfun.com part LCD-00812 approximately $25
3. Solderless Breadboard 2.14" x 6.5"
   makershed.com part number MKEL3 approximately $8
4. Solderless Breadboard Jumper Wire Kit (optional, you can use 22AWG wire off a spool)
   makershed.com part number MKEL1 approximately $6.25
5. An LED of your choice (optional)
   I don't have a specific type for this part, pick any but the 1 watt models.
6. A resistor of a value suitable for your LED (required only if using the LED)
   Use an online LED calculator such as this one to obtain the correct resistance for your LED.  Note that the source voltage will be 5 volts.  Your LED should include a data sheet detailing the voltage drop across the LED and the forward current.  You'll plug those three values into the calculator to obtain the correct resistor value.

* There are currently two revisions of the MiniUSB Module, the newer model has fewer pins than the original and omits control lines that may be used for connecting LEDs or other switched applications.

** Note that LCD panels natively come with a parallel interface.  The serialized models have a secondary controller attached which accepts serial and drives the parallel display.  The controller is also responsible for managing text wrapping and other convenience features such as backlight drive and control.  It makes more sense to pay the premium for the serial edition to avoid adding a complex component to your design.  Also note that there is now a 3.3-volt edition; to avoid additional power conversion circuits you'll need to ensure you're ordering the 5-volt edition.

For convenience, a good breadboard, a pre-cut jumper wire kit, and a multimeter (aka DVM,) should appear in your toolkit.  Radio Shack sells suitable parts, except for the pre-cut jumper wire so be sure to select a good solid core 22AWG wire spool if shopping at Radio Shack. While you're at the store, go ahead and invest in a soldering iron and a spool of rosin-core solder.  This will give you a valuable tool for reconnecting broken leads or connecting new ones in a more advanced assembly.

After prototyping the Display on a breadboard, it makes good sense to plan a more permanent design.  A breadboard loosely holds the connections together, and the display itself is probably not strongly mounted.  It's also rather unsightly for the gentleman or lady's numerical machine console.  Much better to repackage the contraption in a nice project box or handmade enclosure.  How to do that is beyond the scope of this brief introduction, but should be on your mind as you place part orders and consider a longer view of your Display implementation.

Writing to the display:

This introduction assumes the reader is more familiar with software development than the author.  My experiments thusfar have been limited to using a terminal emulation program and Python with the pySerial library.  The key point is that whatever environment you choose, you'll want to access the serial port, send data at 9600 baud, eight bits, no parity, one stop bit - and if possible also control the Ready to Send (RTS) and Data Terminal Ready (DTR) control lines.  pySerial offers access to the control lines, and is fairly easy to implement.

<Pyserial example goes here> Google pyserial examples.

The Serial LCD controller has a command library that governs cursor movement, clearing the screen, backlight control, and other functions.  Two things: You'll need to know how to send control characters to the serial port - this is not as trivial in most cases as I expected it to be, and depending on your language of choice, you'll have to implicitly send a character directive that sends raw bits rather than ASCII.  Second, you'll be able to find the screen control commands here (PDF).

I will be at BarcampNYC4 this year

I'll be at BarcampNYC4 this year.  See you there!

Goodbye T-Mobile

After 6 and a half years of service, I canceled my last T-Mobile line tonight.  It wasn't out of dissatisfaction, rather, but one of budget necessity.  The wife and I (for I am now married if you haven't heard,) had been using separate services for a couple years now.  I migrated to AT&T in search of their fast HSDPA "3G" service not long after the Nokia n95 was released in the USA.  Melody stuck with T-Mobile, and had trouble-free service for the majority of that time.  While things looked bright in the economy, it was easy for me to carry a few wireless plans, one to accommodate a Blackberry for work - since it helped me remain more competitive there, one for my personal exploits - and one for Melody.

After the wedding, with the IT job market looking less sunny, it became clear that I needed to draw in much of the discretionary spending - and it made sense to collapse the phone lines onto a more optimal plan.  While I believe, from my direct experience, that AT&T Wireless operates their customer service in a manner which is unsatisfactory and frustrating to the customer, the availability of very good wireless data services fit what I desired at the time.

Throughout the years that we were customers of T-Mobile, virtually every call to their customer service exceeded my expectations and was quite satisfactory.  With few exceptions, the call center staff have been very professional and courteous, and more importantly, have been competent and empowered to make changes to my service or bill to satisfy my requests.  In two recent cases, for example, Melody exceeded her plan allowance by as much as $100 worth of airtime.  In both cases, the call center agent was able to adjust my plan quota retroactively, saving me a tremendous amount of money.

When I had questions regarding the T-Mobile data services, I generally received a competent answer, rather than being redirected.  Most agents seem to be familiar with the feature offerings and how to manipulate the billing system.

If you're shopping for mobile services, you will likely find that the customer service of T-Mobile is more pleasant to deal with than that of AT&T.  I have not dealt with Verizon directly in a few years, and my recent experiences with Sprint lead me to believe that the firm is only interested in upsetting customers and losing business.  No firm in my direct experience has been less satisfactory in customer service than Sprint, and this as recently as 2007.

So long, T-Mobile. 

Joining Logbook of the World

Those of you in the ham radio scene have probably heard of the ARRL's "Logbook of the World" which is intended to make QSL'ing easier for the contest enthusiast.  QSL'ing is the act of exchanging contact confirmations between stations who communicate on the air, usually under challenging conditions, which serves as evidence of a successful link between them.  The ARRL, a national organization of ham radio operators, sponsors a number of contests to challenge operators to communicate under various conditions - such as speaking with someone in all the states in the USA, or reaching out to someone in a group of countries.  The capriciousness of radio waves makes this a fun and entertaining pursuit.

Logbook of the World takes several days to get started, as the administrators send an access code through the post, rather than online.  I'm waiting for that code now.

If you are a ham, you'll be able to QSL me online, but still feel free to send a postcard direct to my home if you like!

73,
KD4ISF

Comment Spam

Sorry for the late approvals on comments.  Comment spam is bad enough that I'm leaving moderation on.

PocketMac for Blackberry - Fix for inability to connect to Bold

I have a Blackberry Bold I formerly used for my work e-mail.  I've been consolidating some of my discretionary expenses, and this was a luxury that I could live without, so I re-purposed the Bold for my personal mail.  Whether I'll sell the device is another decision I'll address later, as I am fond of my Nokia n95 mobile.

Research in Motion distributes the PocketMac for Blackberry product for free, so I snapped it up to synchronize my Mac address book with the Bold.  My previous experiences with the PocketMac product line for Windows Mobile were poor, and the PocketMac for Blackberry product continues to disappoint me.

If you are experiencing an "error 1" where PocketMac cannot connect to the Blackberry, try the following:

1. Ensure that you have completely removed any other Blackberry-related software from your Mac.  This is most likely the Blackberry Media Sync software that Research in Motion provides to synchronize music to your device from iTunes.  Follow the uninstall instructions provided on the Blackberry website at this link.  Rebooting is a good idea, since the Sync software uses kernel extensions and may not know how to unload them.

2. Ensure that you have the Driver Update installed, available at this link.  The Blackberry device should not be connected to the Mac during this installation.  This will bump up the device driver kernel extensions.  The device driver update must obviously follow the installation of PocketMac itself.

3. Ensure that Mass Storage Mode is enabled on the Blackberry device.  This seems to be a key factor for success.  You will find it under Settings > Memory.  There is apparently another setting "Media Transfer Protocol" that must be disabled on the Blackberry Storm - but I do not have a Storm and the Bold lacks this setting.

4. If you see an "Error 4" while synchronizing, you may have forgotten to set the Blackberry's password in the PocketMac software.  Click on the device name in the PocketMac window, click on the Connection tab, and set the password at the bottom of the pane.  Restart the PocketMac software.

More Abstract Tips:

• My Bold shows up in the Apple System Profiler > USB panel as "RIM Composite Device," although many websites refer to "Blackberry Device." This is likely model-dependent, so don't use the device string in Profiler to gauge whether the device driver loaded correctly.
• The updated Device Drivers are really for post-Bold models, like the Storm, apparently - but it probably doesn't hurt to load them anyway.
• There is apparently a bug in the memory card handling of the Bold by PocketMac.  I haven't investigated this yet, but it may impair your ability to use PocketMac to manage music on the Bold.
• There are a plethora of forums covering this problem, but the most informative source is Research in Motion's own technical support website at this link.  Search on the term "pocketmac" for a long list of articles.  I spent a lot more time repairing this than I would have if I had simply focused on the company's tech support site.

Gripes:

• PocketMac's error reporting is awful.  Error dialogs should be clear and obvious without accessing a log window.  If the sync software cannot communicate with the Blackberry device, it should not use an error code, but a string that clearly states that the software could not communicate, and suggest that the end-user check to ensure the device is connected, that the drivers are up to date, and the check for conflicts with other sync software.
• The software should not require a restart when installing.  Is there a reason a device driver extension cannot be dynamically loaded or unloaded?

Comparison with my Nokia n95:

• Nokia n95 has an iSync plugin for the native Apple sync software.  Why not write one for the Blackberry, RIM?
• I can synchronize via Bluetooth with the Nokia and iSync, so I may leave my phone in my briefcase and keep it up to date..

Hopefully this article will shorten the time you need to repair your own PocketMac for Blackberry issue.  Time will tell whether I keep the Bold, as there are some compelling features (style, keyboard, low-maintenance connectivity, fast e-mail client,) but there are several drawbacks as well - such as the limited Bluetooth implementation and less refined desktop software that make the Nokia more attractive.

Curiosity: Epson inkjet cartridges have sensors!

I recently purchased an Epson Artisan 700 multifunction printer to facilitate my prolific photography habits.  It is nice to be able to generate high-quality prints for friends or to decorate the walls, and the old Epson PictureMate was a bit limiting, although handy for my annual holiday card photos.  Although posting photos online is the most expedient way to share pictures with the world, humans often enjoy tactile experiences, and sending a printed photograph can be very satisfying for my friends and I.

The Artisan is interesting and does a very nice job of printing, but the curious part is the ink cartridges used by this technological marvel.  In the past, ink jet printers "guessed" the ink level by perhaps counting the number of times the nozzles were used, or perhaps relying on the end user to observe when various colors ran dry on the output.  There is a deeper story on the use of microchips on the ink cartridge to limit the end user's choice on replacement parts and some controversy around whether manufacturers were prematurely reporting an empty cartridge.  I'll leave it to you to hunt down that if you're curious.

The Artisan 700 carries six ink cartridges.  The pigments are divided into cyan, magenta, yellow, black, light cyan, and light magenta.  I ran out of the light cyan color first - and dismantled the cartridge out of curiosity.  In the image below, you'll see the piezoelectric sensor and the microchip that connects to the sensor.  I was impressed that Epson had chosen to use an actual measurement of the ink level rather than estimating the level, although I suppose if the rate of delivery is consistent from the print head that one could theoretically predict cartridge levels based on counters.  Off the top of my head (and I would never blog if I had to do deep research before posting,) I can't think of why the sensor would be superior to estimation unless the print head valves have substantial variance in ink delivery.  It's probable, but seems as if the volume delivered would be carefully controlled to ensure the print quality was consistent.

I continued to tear down the ink cartridge until I was satisfied that it was empty.  They're still expensive, but I don't feel as if I'm unable to use the full capacity of the cartridge as in previous designs where the printer would declare a cartridge empty before the ink had run out.  I expect some of that was a conservative design decision to ensure the flow of ink was reliable for printing, but the marketing department may also play a role in seeking to sell more cartridges rather than providing customer value.

You can learn more about Epson's cartridges from the company at this link.

Passed the Extra test!

I was only a General class ham for a short time before I needed the Extra privileges.  I'm traveling to Europe in a week and wanted to be able to operate on HF from wherever I happen to be.  Thanks to Robina Asti, W2JYT for hosting an exam session in her apartment last Wednesday!

Repurposed Toshiba laptop supply for Yaesu FT-817ND Radio

I'm traveling to Ireland and the UK next week, and plan to carry my Yaesu FT-817ND for a bit of radio work during the lulls in our trip.  The rig transmits at a maximum of 5 watts, requiring a maximum of 2 amperes to operate.  The rig accepts up to 16 volts DC.  The bundled power supply offers just a meager 0.5 amperes at 12 volts, just enough to run the receive and internal battery charger.  According to Trish's FT-817 QRP Page, the rig will switch to the internal battery on transmit if the external supply voltage is insufficient to carry the transmitter as would occur using a low-current source.  That's great, but the 8 hour charge time versus the 1 hour or so of useful operating time makes the prospect of this hybrid solution not so good, even if I can bridge the receive time with the external source.

One of the great benefits of being a Resistor is access to a large collection of components to repurpose, and one such collection is our big box of wall-warts.  I rummaged through the bin hunting for a supply that put out a nominal 12 to 16 volts and at least 2 amperes of current.  I came across an old Toshiba laptop supply with a nominal 15 volts and 4 ampere capacity.  This supply also has a nice world-friendly input range.

I'm not absolutely sure that the supply won't create enough switching noise to interfere with transmissions or the noise floor on HF, but a quick simplex test on FM with the internal charger running did not reveal any hum on the transmit signal.  I'll work with it more, but I have little time before we depart.

73,
KD4ISF

Passed the General test!

01122009414
Originally uploaded by wwward0.

After many years of holding the Technician class amateur radio license, last Sunday I passed the General exam at the Ham Radio University event in Bethpage, NY.

I've had the Yaesu FT-817 for nearly a year now, and now I can put it to greater use. Of course, now I must device a clever way of getting a useful signal out of my faraday cage abode.

73 DE KD4ISF