Jeff Duntemann's Contrapositive Diary Rotating Header Image

Tutorials

How things work and how to do them

More on the Dell Optiplex 780

Not a great deal of time today, but I realized I left out an important fact about the Dell 780, and presumably the other USFF machines in the same case like the 980: The all-in-one mount is not VESA compatible, and will only take Dell monitors. The all-in-one mounts for the two earlier USFF case styles (SX270 and SX280) took any 10cm VESA monitor. The flipside is true, too: More recent Dell monitors are not VESA compatible, and use the same proprietary tab-and-button mount as the 780-family all-in-one mount. Be careful when you’re assembling a refurb system. Not everything from Dell fits everthing else from Dell.

That said, if you’re going to use a Dell LCD monitor, Dell has a very nice amplified speaker bar that clips securely to the bottom edge of the monitor. It’s the AS501, and you can get NOS units from eBay for $15 shipped. All of the Dell UltraSharp monitors that I have here provide a 5V barrel jack on the back of the monitor to power the AS501. Very good fidelity, and certainly sufficient volume for puttering around your office or workshop. The 780 contains a tiny internal speaker, roughly equivalent to the one in the SX280, but it’s not good for much beyond notification sounds.

Disabling the Intel Boot Agent Admin Password on the Dell Optiplex 780

780 and SX270 350Wide.jpgI’m replacing my venerable Dell SX270s and SX280s with much newer Optiplex 780 USFFs running Windows 7. I have two here now and at some point will buy a third. They’re smaller than even the SX270 and almost dead silent. Not bad for a Core 2 Duo with 4 GB RAM. The machines date back to 2009 and are recently coming off 5-year depreciation schedules, so you’re now able to snag one for $200 or less.

As with the SX270s and SX280s (and in fact with most of Dell’s ultra-small form factor machines) the 780 is a cube farm box, not suitable for gaming or video editing but completely suitable for nearly all office work. The machine was designed for central management, and in both of the machines I’ve acquired, the Intel Boot Agent has first shot in the boot order, attempting a PXE boot through the 100BASE-T port. Boot Agent eventually gives up, but while it’s waiting for DHCP to pass down an operating system (these IP addresses don’t burn worth a cent!) the machine just sits there, adding at least thirty seconds to your boot time.

So I F2’d my way into Setup…only to find myself locked out by an admin password. I tried a few obvious ones, then looked online for some indication how to reset the password, to no avail. I downloaded the Dell tech doc, which sent me looking for a jumper that my machine doesn’t have. I then sent off a message to the eBay seller I bought it from with a polite complaint. Fortunately, the seller (who’s sold many of these things and doubtless hears this question a lot) told me to pull the blue jumper from a header marked “Clear Password” on the mobo near the fan. I opened it up, pulled the blue jumper off the header, and shazayum: No setup password. Once I got in, I pushed Intel Boot Agent way down to the bottom of the boot order. The machine now boots into Windows in seconds.

Bezel Tab Locator.png

If you’ve got a 780 in hand and want to nuke the setup password and get Boot Agent out of your way, here are some tips once you’ve removed the top panel:

  1. The plastic front-panel bezel has to come off first. There are three plastic tabs locking it in place. (See photo above.) Two are flat and easy to see. You pull those gently upward, while pressing the third and less obvious tab gently to the left. The bezel will pivot forward and down, and then off.
  2. There is a wire handle on the disk drive subassembly. Pull up and the whole business will left into your hands.
  3. Three SATA cables connect the disk subassembly to the mobo. You can pull them all and remove the subassembly completely, or you can remove the blue cable and rotate the subassembly 90 degrees to get it out of the way.
  4. Look for a blue jumper block near the fan, clearlly marked “Clear Password.” (See photo below.) Yank it with a needle-nose; your fingers probably won’t be able to get a purchase on it. I have a drawer for such things, but if you feel you may need to set a Setup password on it again someday, put it back on one (not both!) of the header pins.
  5. Reconnect the SATA cable, drop the disk drive subassembly back where it came from, and then put the front panel bezel back. Hook the two little feet at the bottom into their corresponding slots, then pivot the bezel upward until the three plastic tabs lock back into place.
  6. Button it up, connect it back to the peripherals, and boot it. The splash screen says “Press F12 for boot options” but that’s not useful. Press F2 repeatedly while it’s booting, until the Setup screen appears. From there it’s like any BIOS setup program, and you can set the boot order in the usual way.

Password Jumper Closeup 500Wide copy.png

That’s all you need to do, assuming there aren’t other Setup items you need to address.

Some other odd notes on the 780:

  • The Dell all-in-one mount for the 780 and its successors is hideous, compared to the SX270’s or the still better SX280’s. The 780 fits into a sleeve that then mounts to the stand. The fit is tight. You’re better off just leaving it on the desk. It won’t take up much room.
  • There is a PCIE Mini-Card slot on the mobo for a laptop-style Wi-Fi client adapter. I’ve got CAT5E in the walls and don’t need it, which is good, because I have yet to see the adapter itself for sale on eBay, and the tech doc says nothing about installing it. There is an external antenna that mounts on the rear panel and connects to the adapter with a coax cable. I’m guessing that without the antenna, the steel box will keep the adapter from connecting.
  • The 780’s video output connector is a DisplayPort, so if your monitor is DVI or HDMI, you’ll need an adapter cable. (Display Port is basically HDMI with additional DRM.)

So far I like it, though I’m still configuring and installing software. If anything interesting turns up in the future, you’ll read about it here.

Jeff Duntemann’s Metadiet Picobook, Part 6

Wrapping up the series, which began here.

By far, the most contentious issue in weight loss these days has nothing to do with carbs or fat. It’s about the sheer quantity of the stuff that we eat. In one corner are the people who say that one calorie is exactly like every other calorie, and the only thing you have to do to lose weight is to eat fewer calories. In the other corner are people who say that if you eat the right stuff (typically protein, fat, and green vegetables) you can hork down as much as you want and not gain weight.

Who’s right? We don’t know.

We don’t know a great many things about human health. In my view, the ad lib diet question is the biggest single unknown in the whole weight-loss arena. This may be because both sides assume that they’re right (settled science!) and insist that no further research is necessary. Alas, I’m appalled at how little good research there actually is.

But I have noticed something: Carol and I tend to pick up weight when we travel. Part of this may be the fact that we often go home to Chicago on holidays, when there’s loads of snackable sugar around. But it occurs almost any time we’re away for a week or more. When we get home, the weight vanishes over the next several weeks.

Hmmm. When we’re away, we eat at restaurants a lot. When we’re home, we hardly eat at restaurants at all.

I was boggled to learn that many people eat at “sit-down” restaurants four or five times a week. Carol and I eat at restaurants perhaps two or three times a month. Good stats are hard to come by, but this graph (possibly skewed by the nature of the site and its patrons) says a lot. 25% of the respondents confessed to eating out or doing takeout 6-11 times per week. Not per month. Even cutting that in half in an effort to back out selection bias, we still have a quarter of Americans eating restaurant food 12-22 times per month.

Wow.

Note well that I’m not talking about fast-food here. Fast-food meals are fairly small compared to sit-down restaurant meals, and I think their primary contribution to weight gain is unlimited refills on sugared drinks. Writer Tom Naughton tried to get fat eating at McDonald’s for a month and failed. He published his food logs. Morgan Spurlock of Super Size Me fame did the same thing and claimed all kinds of health problems as a result. Spurlock has steadfastly refused to release his food logs (if he indeed ever kept them at all) and so to me his research is “research” and very likely bogus.

Looking carefully at sit-down restaurant meals reveals two things: The portions are very large, and the meals are carb-heavy. Been to Macaroni Grill lately? Egad. You’re looking at a couple of pounds of pasta. Carol and I have also noticed that restaurant pizza has gotten crustier in recent years. Baked potatoes, which I remember as smaller than my fist decades ago, now seem as large as wing-tip shoes. Carbs are cheap. Wheat in particular is cheap, and there are special issues with wheat, as I explained earlier in the series. There is also the natural tendency to eat the whole thing at the restaurant rather than take two-thirds of it home.

If any experiment is possible relating to portion size, it’s this: Stay out of restaurants for a month and see what happens. If you lose some weight, try to do it for another month and see if the trend continues. If it does, don’t panic. It doesn’t mean you have to stay out of restaurants forever. It may mean that you have to cut back, to perhaps one meal a week or so. Say five a month.

My thought on the portion control issue is that portion size does matter, but because it’s so difficult to separate the portion size issue from the carbs issue in restaurant meals, it’s tough to put real numbers to in any reasonable experiment. Eating out less may simply mean eating carbs less, and that’s almost certainly a win.

They don’t state it explicitly, but having looked at the methods of weight-control programs like Jenny Craig and Weight Watchers, I’d say they work because they’re portion-training systems. No, their pre-packaged meals don’t look all that appetizing. They are, however, modest in size and contain enough energy not to shock your body into fat-storage mode. Eating a little less on a regular basis works better than starving yourself for a couple of months and then giving up. Do that and you will gain weight.

Eating smaller portions at home is easier because you control the portions. One trick I’ve seen is just to use smaller plates, so that less food looks like more. Beyond that, it’s just planning. Don’t cut portions in half when you’re getting started. Ramp down slowly. Don’t stop when you feel full. Stop when you no longer feel hungry.

And that’s pretty much all I had in my notes about weight loss. I’ve lost 20+ pounds since 1997, almost all of it from my gut, which is where you want fat the least. I eat low-carb, which for me is mostly low (or no) sugar. I eat high-fat by conventional standards: Butter? Love it. Meat? Lots! Eggs? Every day. By experiment I’ve determined that modest quantities of wheat, potatoes, and rice don’t seem to have the effect on me that they do on many people.

But that’s been the whole point of this series: You cannot generalize about human metabolism. We’re all over the map. You have to do the science to find out what works for you. So do the science. Keep good records. Don’t starve yourself. Be patient. Believe your findings. (That can be tricky when you’re nostril-deep in diet books that all claim to know The Way.)

It’s a peculiar and surprising business. If you learn anything interesting, do let me know.

Jeff Duntemann’s Metadiet Picobook, Part 5

Hypothesis: Eating fat gooses your metabolism, burning body fat.

Experiment: Eat more fat.

Some time back, I reviewed a very old book: A Letter on Corpulence, Addressed to the Public, by William Banting. It was published in 1865, and you can get it for free from Google Books. It’s the earliest I’ve ever seen anyone publish what amounts to an experiment in losing weight. An overweight man got advice from his doctor, tried it, and lost weight. Better still, he published what he ate, and passed out the book (which is more of a pamphlet) to anyone who wanted it. Banting’s diet proved so popular that “to bant” became a Victorian term for what we now call “going low-carb.”

Fast forward to the late 1950s. A physician named Herman Taller, like Banting, got impatient with his own weight. He’d tried the fashionable remedy of his time (counting calories and avoiding fat) without any success. Then, at the encouragement of a fellow researcher, he did something remarkable: He started consuming what could have been as much as 5,000 calories a day, most of it fat. He lost weight.

Also, like Banting, he wrote a book. Calories Don’t Count was published in 1961. Again, like Banting, Taller and his book have been pretty much forgotten. Forgotten, of course, until Gary Taubes redisovered them, and described them both in his 2008 book, Good Calories, Bad Calories.

Taller’s book is mostly of historical interest these days. His science is now 55 years old, and we’ve learned a lot in the meantime. (There are hazards in polyunsaturated fats that we had no clue about in the 50s.) So I don’t recommend it. Taubes’ book picks up the science that Taller began with, and brings it up to the current day. I do recommend Taubes, enthusiastically, and have several times. If you want to know anything at all about human metabolism, he’s your go-to guy.

For this entry, the point I want to make is something that Taubes explained: Going low-carb is an excellent first step. But you can’t just eat protein, or you risk mal de caribou, which is liver overload due to eating almost nothing but protein. You have to eat fat as well. If you’ve reduced your carb intake, eating fat begins a remarkable process: fat mobilization. Your body runs out of convenient carbs in the bloodstream, and begins to burn stored fat for energy. Your metabolism ticks up sharply. You generate more heat. It’s a weird concept, but I did the experiment. It works.

Here’s how: I banished all carbs from my breakfast. No sugar, no grains, no juice, no fruit. What I began eating (and have eaten most days since) is an egg fried in butter, sometimes two. Coffee with cream. Some days (not always) full-fat unsweetened yogurt. An odd thing began to happen. Within twenty minutes to half an hour, I started to sweat under my arms.

I added up the calories, and it was about a wash compared to a bowl of Cheerios. But when I ate Cheerios, I didn’t sweat. I got a little sluggish, in fact, an hour later, in what was literally a Cheerios crash. The key is that I hadn’t eaten any carbs since the previous evening’s meal, and had gone all night without eating anything. By the morning, I was out of carbs. There was nothing to stoke the fires but protein and fat.

As with everything I’ve suggested in this series, it may not work this way for everyone, but the biochemistry seems legit, and it certainly worked for me. Try it. Lose your fear of fat. There’s nothing to it. When I ate more fat, I lost weight, and both my bad cholesterol and triglycerides went through the floor. By conventional measures I’m healthier than I was when I was 45. I credit that to eating more fat. (The kidney stone just pushed me in the right direction.)

Tomorrow: Wrapping up.

Jeff Duntemann’s Metadiet Picobook, Part 4

Hypothesis: Wheat sensitivity makes you gain weight.

Experiment: Go gluten-free.

(Quick note: This is a series. If you haven’t been reading it from the beginning, please go back and do so.)

Wheat is a weird business. Furthermore, the current emotional furor about GMO foods has muddied the water horribly. When people think “GMO,” they imagine legions of scientists in blinding white labs teasing DNA strands out of organisms and inserting artificial genes with nanogrippers. Or scanning-tunnelling electron microscopes. Or black magic. People forget that homo sap has been doing GMO for ten or fifteen thousand years. Selective breeding and hybridization (not the same thing) have turned wolves into dogs, grass into corn, and (different) grass into wheat. Nanotechnology not required.

The mud in the water comes from a widespread impression that if a food plant is “natural” (i.e., untouched by high tech) it’s completely safe to eat. GMO is fine as long as you leave the DNA intact.

Alas, hybridization does not leave the DNA intact. This is new knowledge for me, and a lot of what I know comes from an excellent 2011 book called Wheat Belly by William Davis . The publisher appears to have wanted a diet book, but what they got was heavy on the science. Some of that science is disturbing, to say the least:

Analyses of proteins expressed by a wheat hybrid compared to its two parent strains have demonstrated that, while approximately 95 percent of the proteins expressed in the offspring are the same, 5 percent are unique, found in neither parent. Wheat gluten proteins, in particular, undergo considerable structural change with hybridization. In one hybridization experiment, fourteen new gluten proteins were identified in the offspring that were not present in either parent plant. Moreover, when compared to century-old strains of wheat, modern strains of Triticum aestivum express a higher quantity of genes for gluten proteins that are associated with celiac disease. [pp 25-26; author’s emphasis]

To make a long and unnerving story short, 10,000 years of meddling have made wheat’s genome very odd. Accelerated hybridization in the last 100 years has accelerated its oddification in tandem. Now we’re finding that more and more people just can’t digest the stuff well. A small but growing cohort (celiac sufferers) can’t digest it at all.

I don’t have this problem myself. However, a number of close friends do. In addition to digestive difficulties, wheat sensitivity makes people put on weight, particular around the waistline. Two of my friends have cut back on wheat gluten and by doing so have lost a great deal of weight. They also feel a lot better.

It’s a difficult experiment to make, more difficult than cutting back on sugar. Sugar is in a lot of things. But a lot of other things are wheat and little else. The bulk of the grain carbs we eat are wheat, and the cheaper the wheat, the more likely it is to be a modern hybrid. Gluten-free baked goods and pasta exist, but they’re not common and they’re relatively expensive.

Worse, there are no generally accepted lab tests for non-celiac wheat sensitivity. The only thing you can do is cut out wheat and see what happens. Again, Carol and I don’t have the problem, but we’re aware of the issue, and we try to buy imported pasta that isn’t as likely to be hybridized to the extent that mass-market pasta is. I’m trying to move my carb intake (reduced as it’s become) to corn and potatoes. This is bitchy because I’m sensitive to corn bran. But it does give me an excuse to stick with potato chips.

It’s not obvious to everybody, but beer is a wheat product, and going wheat-free means going beer-free. There are gluten-free beers. I don’t drink beer and don’t know if they’re any good. If you just want the buzz, red wine is better. If you’re really attached to beer, you may have to do some hunting.

I’ve been asked an excellent question: How do I know if weight loss experienced after going gluten-free is due to gluten exclusion and not simply reduced carbs? Answer: I don’t know. It is true that wheat’s ubiquity makes it hard to go gluten-free without cutting carbs drastically, and that makes single-factor experiments tricky. I guess you could boost your consumption of other starches in compensation, but starches are still carbs and do affect insulin regulation. My suggestion: Hold your non-wheat carbs steady and try gluten-free for a month. If you lose weight, keep at it. Weight loss is good even if you’re not sure precisely how it happens, and this is one instance where controlled experiments may not be possible.

So. Sugar and wheat are the first things to go after in your metadiet experiment. Next: The Magic Ingredient. (I may need to post an Odd Lots first.)

Jeff Duntemann’s Metadiet Picobook, Part 3

Hypothesis: Sugar makes you fat.

Experiment: Stop eating sugar.

I came upon this whole business when I threw a kidney stone in late 1997. It was very unpleasant, and my urologist told me to drink nothing but coffee and water until the stone was recovered and analyzed. I did as he said. The biggest change was to stop drinking two (sometimes three or four) Snapple sweetened iced teas every day. Tea is a known factor in kidney stones, though not the only one. I did not expect what happened next: I lost weight in a big damned hurry.

The weight went fast enough that, fascinated, I continued the experiment long after the stone report came back. I gave up both sweetened and unsweetened iced tea almost entirely, for obvious reasons. I gave up sugared sodas generally. (This was when I began a love affair with Diet Mountain Dew that lasted ten years.) I stopped snacking on cookies and other sweet things. I did other experiments over the next several years, and I’ll describe them in coming days. In my case, sugar was the big one.

For most people, it may also be the hardest. I admit that there could be a Fox and Heron effect in play for my own situation: I’ve never really loved sweets, so giving them up was no huge effort. Most people I’ve talked to and read about report that giving up sugar is tough. Whether sugar is addictive is still being debated. However, there is an enormous amount of research indicating that most individuals gain weight eating sugar. I know at least one person who doesn’t, and I suspect that there is a smallish human cohort who just handle sugar and carbs better than most of us. Everybody else is going to have to go cold turkey, whatever it takes.

The case against sugar is most clearly made in Gary Taubes’ book, Good Calories, Bad Calories . It’s long, and technical, and can be a slog in spots, but I’ve read it twice and will read it again in the near future. It’s the best description of sugar metabolism I’ve ever seen. It’s how I learned that fructose is metabolized in a completely different way than glucose. Read the book, but here’s the short form: Glucose messes with your insulin levels. Fructose messes with your liver and your triglycerides, which are fat precursors. Either will put fat on you, and sucrose contains an equal measure of both. Whether fructose is worse than glucose is still being debated, but there is clear evidence that overdosing on fructose can destroy your liver. (This may also be why we lost celebrity fruititarian Steve Jobs decades before we should have. Fructose appears to be the food of choice for malignant tumors.)

Giving up sugar is doubly hard because it’s in almost everything, even a lot of things that don’t taste particularly sweet. That said, most of the sugar we ingest these days comes in through sweet drinks, particularly sodas and fruit juice. Dry wine contains almost no sugar. Beer contains very little simple sugar, but may be fattening through a completely different mechanism, which I’ll get to in coming days. Milk contains a little sugar in the form of lactose, probably too little to be a serious fat-factor.

A few researchers say that sweet tastes are enough to make you fat, and that non-sugar sweeteners won’t help you. This cooks down to insulin sensitivity, which varies hugely across the human species. Some people’s insulin systems are so sensitive that sweet tastes of whatever source cause an insulin pulse. However, like the people who can ingest all the sugar and carbs they want without putting on weight, this is a minority trait, on the opposite extreme of the sugar-metabolism spectrum. I’ve known a number of people, some of them quite well, who lost an enormous amount of weight simply by switching from sugared sodas to diet sodas.

So if you really can’t eliminate all sugar from your diet, at least get rid of the obvious sources: Sugared drinks and sweet snacks. Give it a month, and if the trend is in the right direction (even if it’s not a huge trend) give it another month.

Note well that I only mean sugar here, not carbs generally. Carbs are not all the same. This is a point that I’ll come back to later on.

Jeff Duntemann’s Metadiet Picobook, Part 2

To begin: Everything you think you know about dieting is wrong. Put it all out of your head. You’re going to have to start from scratch. This is work. It’s also a species of science. You’ll have to be rigorous and consistent, which involves four important first principles:

  • Keep good records. This suggests a calendar, but all those little squares on calendars just aren’t big enough. I’ve been tempted to write an eating-specific database utility in Lazarus, and I may if time ever allows. In the meantime, an ordinary diary in a text document will do.
  • Change only one thing at a time. Jumping feet-first into a whole new way of eating may lose some weight for you, but it won’t teach you anything about losing weight. Learning what works is the whole idea here.
  • Record consistently. Weigh yourself on the same scale at the same time every day. Ditto blood pressure, if you choose to record it.
  • Don’t give up. Individual metabolisms have inertia. The process may take some time.

Here’s what I call the Jeff Duntemann Metadiet: You’re going to try a number of relatively narrow changes to your daily diet, one at a time, and record what happens with each. Some will work. Some won’t. Continue with any change that works. Abandon any changes that don’t. Repeat until you’ve lost the amount of weight that gets you where you should be.

The above paragraph comes in at under 100 words, so it’s what I call a picobook. If it had come in at 10 words, it would have been a femtobook. IBM published an attobook once. It was a runaway bestseller. Anybody ever read it?

If at all possible, get some fresh blood numbers before you begin. If you’ve had a recent physical, that’s perfect, and it doesn’t have to be yesterday, just within a year or so. If you’re lacking a recent physical, I’ve had good luck with a chain called Any Lab Test Now. You don’t need a prescription or a doctor appointment. Also, their phlebotomists are among the best I’ve ever experienced. Other such labs are all over the place, and they’re not horribly expensive. Weight is only one indicator of health. Get your cholesterols and triglycerides at bare minimum. Record your blood pressure as you go, on a daily basis.

A sidenote: Exercise doesn’t really help you lose weight directly. It has lots of other benefits, especially training that builds muscle. Since muscle consumes energy 24/7, exercise helps indirectly by goosing metabolism. But we don’t burn calories like we burn charcoal in a grill. Calories don’t count. (Doctors knew that in 1964. By the late 1970s, they’d forgotten.) The type of calories counts critically.

Another sidenote: The BMI is bullshit. It doesn’t distinguish between fat and muscle. If you’re in the process of losing fat and gaining muscle, it’s less than useless, and I will no longer discuss it. Don’t even bring it up.

Still another sidenote: There are other causes of overweight beyond diet. Genetics is big, as is the state of your endocrine system. You may not be able to eat your way skinny. My experience and research suggest that you can eat your way healthy.

The last sidenote (for today, at least): Don’t starve yourself. Eating less generally is a good thing, considering how much we eat, but taper off slowly. Going off a calorie cliff kicks survival mechanisms into gear that you don’t need, and over the long term will only make you gain weight again.

Tomorrow: The Biggie. I suspect you already know what it is. I suspect that you’re right. Get that calendar ready. And put down that doughnut.

Measuring Raspberry Pi USB Power Draw

Smartronix USB Meter.jpg

Most of the problems that turn up while configuring Raspberry Pi systems cook down to inadequate power. The infamous stuttering keyboard problem vanished immediately here when I put the RPi on a stiffer 5V supply. When I bought a second RPi for a programming system, I incorporated a powered hub capable of sourcing 500 ma from each port, and in doing so strangled the power problem in its crib.

Problem solved, but I still wondered: How much juice do these things actually need? How stiff is the 5V supply? I’m a bench tech, and not being able to do actual measurements made me nuts. So I sniffed around a bought a test instrument for measuring voltage and current at a USB port under load. It’s the Smartronix USB Power Monitor, model ST034TT05-01-001. I bought it from CyberGuys; $49.95.

It works like any current meter: You connect it between a USB port and a USB device. It simultaneously measures the voltage on the port and the current through the device. There’s a full-size Type A jack on the right side of the box for connecting the load, and a full-size AB cable plugging into a B jack on the left side of the box, which plugs into a Type A port.

Works like a charm. I did the measurements below in about ten minutes:

Raspberry Pi board running Raspbian, w/o Wi-Fi 50-73 ma
Dell 0C8639 wired USB mouse 5-17 ma
Dell SK8135 wired USB keyboard 53-56 ma
AirLink AWLL5088 Wireless N Ultra Mini USB Wi-Fi 32-80 ma
SanDisk Cruzer Mini thumb drive, 256 MB 27-30 ma
SanDisk Cruzer Micro Skin thumb drive, 256 MB 75-89 ma
San Disk Cruzer Mini thumb drive, 512 MB 7-11 ma
KingMax Super Stick thumb drive, 512 MB 35-62 ma
SanDisk Cruzer Mini 1 GB thumb drive, 1 GB 5-11 ma
SanDisk Cruzer Micro Skin thumb drive, 4 GB 75-91 ma
SanDisk Cruzer Micro Skin thumb drive, 8 GB 43-70 ma

In the readings above, the two numbers are the range across which I saw current run. In most cases, the first number is when the device is idle, the second is when it’s busy. All measurements were taken from the same USB port, one of the four ports on the Rosewill powered hub. All devices tested are USB 2.0, because the meter itself is not listed as capable of testing USB 3 devices.

I have several of most of the thumb drives, and identical models were almost alike in their power behavior. This made me wonder how the Cruzer Minis managed to use so little power while doing the same task that all the other drives did. In this case, the task was copying a 109 MB file (the Lazarus 1.0.6 installer) from the PC to the thumb drive. One would think that smaller drives would draw less current, but not so.

Probably the biggest eyebrow-raiser was how rubbery the 5V USB rail is on my quadcore. An 8GB Cruzer Micro Skin thumb drive pulled the port down from 4.99 v to 4.91 v while drawing 90 ma. The same drive pulled the Rosewill hub supply down by only .02 v , from 5.17 v to 5.15 v while drawing 70 ma. (Current draw in thumb drives is not the same on the RPi as it is on Windows.)

My only gripe about the meter is that “peak” mode displays the highest values for voltage and current, when voltage and current generally move in opposite directions as load increases. So a downward movement in voltage isn’t registered in peak mode.

Other than that, it works as described and answered a whole lot of questions about what sorts of things I can reasonably expect to connect to a Raspberry Pi’s built-in USB ports. Actually, I now recommend using the powered hub for everything, given the RPi’s touchiness about power. It makes the RPi system bulkier and snakier, but a whale of a lot more reliable.

And as for the Smartronix USB power meter, let’s say solidly (if not quite highly) recommended.

The Raspberry Pi Keyboard Stutter Problem

When I first cabled up and ran my Raspberry Pi board, it worked like a charm, first time. I was powering it with the Motorola Droid X2 charger that I had stolen from the kitchen desk upstairs. To keep peace in the valley, I went out and bought a cheap Micro-USB phone charger at Best Buy. It booted normally, but then, when I tried to log in, the keyboard began repeating characters. I’d type in “pi” and see a parade of extraneous i’s march in stately fashion across the display:

piiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiii

Needless to say, I couldn’t log in. Now, this didn’t happen every time, but probably half of all logins I attempted failed, with the same keyboard jitter. I tried two other USB keyboards I had on the shelf plus the known-good one attached to my GX620 USFF, and saw exactly the same behavior. It clearly wasn’t the keyboard itself. I’m using a Dell SK-8135 keyboard, which has a 2-port USB hub to which a Dell USB optical mouse is connected. This leaves one USB port on the RPi free, with any luck to use for thumb drive add-in storage. More on that once I figure it out.

Anyway. Some googling suggested a power supply shortfall. I got out my DVM and put the probes on test points 1 and 2. These are minuscule “doughnut” pads on the RPi circuit board. One is labeled TP1, the other TP2. Hunt around on the board for them; it’s not like there are a lot of square inches to search. TP1 is located next to the 220 uF filter cap at the Micro USB jack. TP2 is right next to the yellow RCA jack.

The RPi is designed to work at 5V. Anything much below that and things may start getting flaky. My reading across the test points was 4.72V. Aha! We now have a new phone charger for the kitchen desk–a cool one with a retractable cord–and I decided to dedicate the old one to the RPi. With the original Motorola Droid X2 charger in the wall, I measured 5.03V across the test points. Shazam! No more keyboard stutter.

I’m not sure it’s a question of the RPi drawing more current than the charger can provide. The Droid X2 charger that works is rated 850 ma. The no-name charger that provided only 4.72 volts is rated 2.1 A. Current sourcing ability is important, especially since different USB keyboards and mice draw different amounts of power–but accurate voltage is just as important. I’m guessing it’s sloppy voltage regulation in the cheap charger. If you’re getting keyboard weirdness, put your DVM on the test points and see what your charger is feeding the RPi.

What? You don’t have a DVM? No Pi for you!

Behold the EggMcSpamFin!

EggMcSpamFin-500Wide.jpg

The place is a mess. Not as messy as it’ll be by tomorrow night, but it’s still a mess. The movers got everything transferred to the uncarpeted portions of the lower level yesterday, and the carpeting has been pulled up. Plastic tarps are all over the place. Tomorrow the drilling begins.

lilfrypan200wide.jpgIn the meantime, when Carol and I broke for lunch an hour ago, I tried something completely different. I scrambled a single egg in a bowl, dumped some butter into the little one-egg fry pan that I’ve had for years (left) and with the burner on medium made a scrambled egg disk. I then threw a Bay’s English muffin in the toaster, and while it was toasting I broke open a Spam Single onto a Corelle plate and heated it up to a nice sizzle in the microwave. When the muffin came out of the toaster I buttered it good and proper, threw the scrambled egg disk on a muffin’s lower half, lowered the sizzlin’ Spam Single onto the egg, and then slapped the muffin lid on the whole business.

Damn, that was good! Cheap, too, as lunches go. Eggs are about 20c each. Spam Singles run about a buck. A single Bay’s English muffin costs me about 40c. Might have used a nickel’s worth of butter. Total $1.65. Almost entirely sugar-free. Filled me up completely and will probably carry me all the way to suppertime without any need to snack. It would be less fattening without the English muffin, but try as I might, I can’t do completely without English muffins.

Highly recommended.