2022-05-14 - Tech - Raspad - Beat the Clock

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Being the continuing adventures of a solarspinster seeking to deploy a Raspad for a purse bound infotech doodad. I spent a day setting up services and muddling through man pages. Learning by man page is a slow trek. But such is the pace of offline life.

So in pursuit of a leg up, I asked my friend Vidak what he might know about Raspberry 4’s power management. Perhaps I might better understand the stakes if not solve the issue of battery consumption. Vidak recently began a Peertube introduction to unix systems for which I hazard to need repeated review, q.v.:

https://diode.zone

Tweak Tool

Fools proverbially rush in, and so I gathered a glimpse of my ignorance of the Raspi systems when Vidak clued me in to

which apparently is a standard ncurses gizmo for baking the Raspi as one pleases. This was notably *not* installed standard to Ubuntu MATE for Raspberry Pi, an oversight which I shall remedy anon. But it was on RaspiOS, which I had on a backup microSD card. Sure enough, the canny multi tool has a performance section and can be used to set Raspi clock speeds… …but only for Pi versions 1 & 2.

Still, a delight that it can set the size of the GPU memory. I eagerly upped mine to 256Mb.

MATE Muddles

In search of more answers, his own curiosity piqued, Vidak was kind enough to ask the Fediverse for input on the issue. Some kind soul immediately replied that I might check the /root/config.txt for a variable named “ARM_SPEED”. This one could set to any integer in reasonable orbit of 700 MHz as one pleases.

Swapping MicroSD cards between Ubuntu MATE for Raspi and RaspiOS, I found that the solution only applies to the latter OS. It does indeed work to under or overclock the CPU. I tried the CPU on 200Mhz and found it pitiably slow, but emphatically cooler. Poking at the config.txt revealed several other bits to flip for services on the Raspi.

MATE sets config text files plural, named by relevant kernel number, I take it. Reading through, I found a trove of settings, even more than for RaspiOS. This included a few settings regarding CPU frequency scaling, which is what I desired. But the user is therein sternly warned not to change these values manually, as the config files are autogenerated. What widget sets these, and how I might play with it, is not yet determined.

The MATE boot config.txt does make me optimistic that some such doohickey might be available or easily created. The section for frequency scaling had the same preset dynamic preferences as my laptop’s MATE panel widget, which widget works wonderfully… on an intel chip. These were present and flipped to “y”, so perhaps they will work for the Broadcom chip on Pi, too. Hopefully they likewise can be changed and effected hot, as works for Intel, as rebooting for cpu clock speed is a bore.

It was telling that the cpu speed profile set as default is “Performance”. This no doubt accounts for the hairdryer effect of the Raspad at present. All fine and good when on power or when one needs graphical oomph. But for daily chores in the purse, I’d like more decorous sips from the battery.

Look on the Sunny Side

The battery life on MATE isn’t bad so far, really. I tested it yesterday morning at 3 hours full usage on battery, typing and popping open programmes. But of course we can and must do better than that. So as things stand:

The MATE power performance panel programme may be able to manage the CPU on a tighter lead. If not, some solution must be out there or in the works, as the ARM chip does indeed respond to messing with the clock.

The screen is very bright! This even on the lowest setting the daughter board affords. Good for outside by day; less needful indoors or at night. Looks like lowering the voltage to the hdmi display might help. Experiments forthcoming, once I’ve perused the forums a bit.

The fan can be set to high or low from a switch at the Raspad daughterboard. But a fan connnected to a GPIO rail can evidently be managed through the Raspi-config programme. Of course, it makes sense to not use the GPIO pins unless necessary. But some combination of dynamically temperature responsive widget and a hard switch on the fan rail might make the fan less a nuisance. A Maxwell’s daemon, if you will.

A battery expansion to double the bank is a good idea at all rates. Hopefully the controller bundled with the batteries will do for two. It bears research.

Speaking of Clocks

There is another small, basic, but vital deficit to the Raspberry Pi as an information prosthetic. Apparently these boards have no system clock battery. When powered off, the devices float in temporal stasis, as it were. For most people in our era this is not too relevant. When online, the system clock is automatically reset from the NIST signal or such. But if one is stubbornly offline, another signal must compensate. It isn’t too much issue to reset the clock by hand, if a bore. I am hoping that in due course I can have the clock reset by Bluetooth from a GPS device.

Man-ia

Man pages really are an awful format. As a reference, they often are overly verbose to the point of obtuseness. This, save those perfunctory pages which don’t tell nearly enough. The vast majority lack any examples at all.

Bro pages are helpful indeed, but require online access. The woman pages of GNU I find most helpful lately. Concise tabbing prompts, like the options of gpg, for example, is how all CLI programme help aides ought to work.

But when one must “man” up, grep is one’s best friend to ensure keeping the soul of wit.

Blueman-ia

I have tried Blueman, the default Bluetooth manager for MATE, on several systems. On every system I’ve found it finicky at best. I have gotten it to work for my keyboard-trackpad, finally. And it thankfully can hold a signal for headphones. But re-pairing is apparently beyond its grasp. I’ll be swapping this fickle kit out ASAP.

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