Amateur Radio Astronomy

Serial and Parallel Port Options

2009-01-05T07:46:00.003Z

Access to computer serial and parallel ports has been important for hardware hackers who wanted to control their creations with a computer. Those ports are disappearing from new computers. The serial port seems to be maintaining a tenuous hold in the form of USB to serial interface devices, many of which are based on specialty chips from http://ftdi.com . This company makes some relatively inexpensive modules like the UM232R which can emulate a serial port in software, that is, your program thinks it is talking to an old standard serial port. One fairly exciting feature of the UM232R is that it has a "bit bang" mode where instead of acting like a serial port it can produce inputs and outputs on some of its pins. For some applications this could replace the functionality of the old parallel port model where individual pins on the port were toggled to produce a given result. Of course, for a few more dollars you can add a microcontroller like a PIC greatly increasing the functionality of the system.

Adding a parallel port PCI adapter to a PC motherboard that does not have its own integrated parallel port does not always give the desired result. Many of the parallel port boards will not map their base addresses to the old standard addresses of 0378, 0278, or 03BC hex. If your application requires these addresses be careful. If anyone has a lead on a card that is available and will do this please drop me a line.

Note also that parallel to USB adapters will not work because they do not present themselves as I/O ports to the software side. There is an exception that I have not tried myself: http://www-user.tu-chemnitz.de/~heha/bastelecke/Rund%20um%20den%20PC/USB2LPT/ul-15.htm.en
Device are not always available and there is no commercial source though the author invites duplication.

Plumb Wrong

2008-12-21T05:54:00.004Z

This week I solved a plumbing problem and it might have a lesson in troubleshooting that could apply to radio astronomy (electronics). I just installed a water system in my daughter's cabin. I have done small plumbing projects many times over the years but I think this was the first time I installed an entire supply and waste water system. Here in our part of Hawaii there is no municipal water system. You catch the water off of your roof and hold it in a catchment tank then pump it when you need it with a shallow well pump. My daughters cabin has an outdoor kitchen (common here) and about 30 feet away is the main cabin with a full bathroom.

When I fired up the pump (it is right behind the kitchen) the water flowed from the kitchen faucet just fine. I went into the cabin and turned on the water in tub.. a tiny trickle. Then I tried the bathroom sink, another trickle. Finally I opened the valve to the toilet and again a tiny amount of water began flowing into the tank. What? Something must be clogged in the pipe running from the pump to the cabin, I thought. But all of the pipe is brand new. The kitchen faucet was fine so it would have to be after the point where the kitchen sink tapped off of the supply line. It was dark so I went home and tried to sleep on it.

Next day, I went to the hardware store and bought a bunch of couplers to reconnect the supply line in all of the places I intended to cut it in hopes of finding the clog. I began chopping into the lines close to the pump and stepping towards the cabin, but everywhere I cut there was plenty of water pressure, even right under the fixtures! Could I have three bad fixtures, a tub faucet, a sink faucet, and a toilet inlet valve? Yes!

When I disassembled the valves I found each one clogged with little bits of PVC pipe and blue "Rain & Shine" PVC glue. I had created the problem in all three fixtures by using an electric trim saw to cut the pipe (which produced the shavings) and too much glue when putting them together. As I painstakingly unclogged each fixture with a bent bobby pin, I pondered how this related to many of the more horrific electronics problems I troubleshooted (shouldn't there be a word 'troubleshot'?) over the years.

We usually assume that ONE thing is wrong in a failed system, but you don't have to spend too many years fixing things to find out that multiple component failures are common. The electronic system outputs are our usual indications that something is wrong. No lights at all or all dim lights (trickles of light..) would immediately signal power supply problem to me, but that conclusion can be very wrong. Each of the "lights" could also be failing. Another point; in a system that you design and/or build from scratch your technique in assembly could lead to failures in multiple places, cold solder joints for example.

I can believe I am blogging!

2008-12-16T09:36:00.002Z

I resisted this for a very long time. But here I am jotting down my thoughts for public consumption. Expect to find here notes and newsy bits from the world of amateur radio astronomy of which I have been a part for at least 20 years. Most people know me from my website at http://radiosky.com where I have some books and programs that may be of interest to you.

Thanks for dropping by.