Jetson Nano and Raspberry Pi 4

December 2019
Jetson Nano and Raspberry Pi 4

Purchased a Jetson Nano when it first came out (5/22/2019) to try and understand its unique place in the Single Board Computer (SBC) space. This video from Explaining Computers can help understand the specifications and this video the artificial intelligence use case.

I found after a few months that the bare bones computer had been accessorized, so thought that should be written about. At the same time, Raspberry 4's came out, with a much lower price point than the Jetson Nano, but different use cases. So here is an attempt to show how them compare and contrast, possibly from a different perspective than most others.

To eliminate any suspense, here is a photo of my current accessorized Jetson Nano:

Which includes:

• Audio board and headphones. (USB audio board w/PCM2704 chip, no microphone)
• 120 GB USB 3.0 SSD 
• MicroSD card
• Transparent case with 5V fan
• M.2 Key E WiFi/Bluetooth card & 2-antennas
• Wireless trackball mouse
• USB keyboard
• Display-port graphics cable to a 
• High quality curved 24" monitor.
• Raspberry Pi Camera

Been using the Jetson Nano as a desktop for a few months now.

And here is a photo of a Raspberry Pi 4 with 4 GB of RAM.

Same monitor (HDMI), camera, keyboard and mouse is connected to this SBC. A Raspberry Pi 4 comes with audio, WiFi and Bluetooth, so those costs at about $30 aren't required with the new Raspberry Pi 4. Lets call it $62 to accessorize the Nano, not including the monitor, keyboard and mouse. Accessorizing the Raspberry Pi 4 (RPi4) also has small costs, especially if interested in speeding it up with a SSD. Inside the plastic housing the actual hardware is quite small. This can be folded into a case quite easily. Both the Nano and RPi4 can be configured to run off the USB 3 SSD.

Raspberry Pi 4 is small, lighter than the Nano developer kit, has audio (headphones output and microphone input). Both need a power-supply; the Jetson can use a standard USB micro 5 watt which you may have laying around. The Raspberry Pi 4 is now using the USB C, about the same price. Both need a Micro SD card.

I haven't tried the Jetson Nano with a high wattage power option yet, but comparing the two boards with an older performance benchmark called Octane they both have about the same score. I'm assuming with a larger power supply the Jetson Nano would have much higher benchmark score.

The differences between these two systems primarily comes down to graphical capabilities. The Jetson Nano has both an HDMI and a DisplayPort connection. The RPi4 two HDMI micros. But the real power of the Nano SBC comes from its ability to do image analysis. It will do artificial intelligence of recognition services very powerfully. The real heart of the Jetson Nano is the little card, called the NVIDIA Jetson Nano module. The bulk of what you buy when you get the developer kit is the carrier board. The carrier board is the piece with all the connections. The module is what does all the work. So you can program the module to go out in the world and do lots of work, mostly image analysis applications. I assume audio analysis will be next, but the NVIDIA world obviously didn't concentrate on this use case for the Nano because of the lack of on board audio interfaces.

One other observation of note. The Raspberry Pi community is head and shoulders better at supporting their offerings than NVIDIA. Yes, there are Jetson Nano user groups, but they are overly moderated, and not very informative when newbies ask questions. The Raspberry Pi community is quite forgiving.

I've seen lowered prices on the Nano at Newegg this holiday, and lowered in store priced RPi4 at Microcenter.

Around the Eye on the White Rim

by Jhose' Mc.

Oct. '19

This will be a quick report on the bike trip. Thursday afternoon my driver picked me up at the west light rail station and we were off. Heading west to Fruita where we met up with some of the team at the Hot Tomato pizza joint.

Good time re-acquainting, then Hotel La Quinta. Expensive bikes brought into rooms, other ones locked on bike rack on car. Morning breakfast was as expected, not worth writing about. Real coffee across the parking lot. Then we drove to the Eye in The Sky, waited. In the background some gas up and car shuttle activity was happening unbeknownst to me. To tell you the truth, I didn't know how cars, bikes and people were all going to be moving back and forth. When all the people arrived, we packed up three cars and waited for bikers to start the decent into, onto, down to the White Rim. 

First Day, Going Down

White Rim has a complete new meaning after having experienced it and can't be explained without having been there. But here is a try. The layers of Canyon Lands have different colors, depicting different eras of sedimentation. Rivers have carved away the rock layers revealing the history. The white layer on which we rode most of the White Rim must have been very hard to erode because it is the top layer a thousand or more feet above the rivers. Two rivers come together to form the midpoint of our particular journey, the Green on the right (as you go clockwise) and the Colorado river on the left. The first two days we were going along the meandering Colorado on its right. Up and down the White Rim path. Mostly white, sometimes red and if you didn't have glasses on you would see the blue. Still trying to figure out what oxidized element caused the blue. Everyone I asked had polarized glasses on and didn't see the azure. The third and forth days we had the Green River on our left, heading back to the Eye in the Sky visitor center. 

Similar to river trips, each day consisted of a routine.  Travel by bike or in a car, set camp, eat, break camp, pack, car or bike again, repeat till finished. There were drivers, cooks and clean up crews. And the best decaf coffee with ice cream and tequila and baileys. I just had the decaf as the certified always available designated driver. Camp sites varied some with shade, and others full sunlight and moon light. The moon greeted us each night soon after the sun set, typically rising over jagged rock then setting before most awoke. 

Here is a passage I wrote the first morning: 

***********
Sitting here in limbo with Dan, six forty am, about an hour up. Constitutional, coffee, another coffee, and another constitutional. Teeth, everything is good.

Was dark at first with the light of the moon casting cathedral shadows across the plateau. Then that set, and the milky-way came out slightly, a glimpse of the infinity. The sun peaked over the east horizon with the terrain lines showing the southwest topography. You see this in southwest art, a black mountain range with rising colors. The light, or lack of light danced this morning. I could always see the outline of the campsite road, but couldn't see it in full sunlight yesterday afternoon.

We have eight tents, plus one where Mitch and Milan have two tadpoles quite close to each other, on a flat area at the bottom of the road. Camp A is higher up from the outhouse, a ridge-line protects from easterly winds. Not too many flat sites, but everyone manages.

The sky has a color pallet, black at the ground, orange at the ridge lines where the sun peaks out, yellow above that, light blue, darker blue then a dome of real blue till you get to the west where you can see the striped red rocks carved out by the river, hills and valleys, amphitheaters, spires, cathedrals. Man must have used these geometries as examples to build their worship structures to the gods, churches. The rocks glow red as the sun rises, but still not up. That cathedral is familiar. Seems to me I've camped at the river on the other side of it. I think we are at a point on the Colorado, above it. Five miles by road if you want to meander down, but maybe a thousand feet above. A point where the river hit resistance and carved a 360 turn. Someday it will all be flat, flattened by the trickle of water that carves forever. Slow forces which we are supposed to emulate in mediation. Water.

Our tent is right on the boundary line. Perhaps a tent or two are outside the boundary but I'm not sayin'. Practicing not being my father. I think it is my mother's birthday, if today is the 12th. Don't know the date, but do know her birthday. 89, she beat the curse of the Halligans / McCabes, all passing away at 87 until she came along; need to update my actuarial tables.

*************

Driving the Jeep Cherokee was exhilarating, adding testosterone regardless of gender. You cannot see what you are driving over when going up the many steep hills. My head plastered to the top of the seating space trying to get the slightest glimpse of what is to come. Head hitting the side walls as left right wheels drop into holes or rise up to meet road ridges. "God I hope a jeep isn't coming the other way over that ridge." Could easily be a flat section that drops down, just as I am rising up. But no encounters on the road, trail, dusty sliver of a corridor. At one point the place where you are supposed to drive was right next to a 500 foot drop, shear rock. And no space to purchase on the other side of the car. I said to myself out loud "Shittt" and the Jeep's automatic voice recognition service came on loudly and startled me. I didn't hear exactly what was said because I was concentrating on not soiling myself. I imagined it saying, "Thanks for choosing Chrysler for your final car purchase."

Here is a video of two of the Jeeps making it up the steep climb the third day, both Jeeps go on three wheels. The other vehicle did the same thing, only much more ground clearance on that tire off the ground. That driver was having a GREAT time, the passenger wasn't. 

Reminds me of my uncle who was a NY taxi driver. Died peacefully in his sleep; not screaming for their lives like his passengers.  

Each day we became closer to our new friends, and understood our old friends better. Nothing too revealing. It was revealing when Cindy came down Murphy's Hogback long downhill run and passed me saying, "That was the greatest thing I have ever done". She has birthed a human, done extreme skiing, and other exhilarating things. I didn't know that speed and downhill was good for her. And where does being married 25 years fit into the whole equation? Oh well, no worries. 

The last day was longer, and more up-hilling than expected. And as it turns out I've been on the last part of Mineral Bottom Road, the rising for ever switch backs. Let me just say that the switch backs were in much better shape than the last times I've been on that road. This time there were no missing sections of road. But alas I did have an argument with my bike chain, which decided to go into hiding between the wheel hub and the largest sprocket. I will fix that soon, but wouldn't be able to on that road, so carried the back wheel up that hill. That wore me out, knowing full well the next day was going to be a hard recovery. And it was.

All in all, with a few mishaps, the gear worked. Cars, bikes, stoves, all got us back home fed, safe and sound. Thanks to all the team that supported me and Cindy. Great bike maintenance by Scott. I swear the chain lube was great. The real hero, the organized one, the guy who got the reservations early multiple days.... Buddha Dan. Thanks Rock Star Dan. 

Kevin was nice enough go get me and my tired legs back to the original starting point, where I drove back to a convenient place to catch Mike's car returning with Cindy. All worked out well and arrived back at home, trying to merge photos with others. Who took what photo will be left to the archivists. For now, we have the before photo with too many layers of clothing, and after photo with lots of red dusted skin showing. Amazing how that dusty sand got into everything including the psyche. Till next time, signing off. 

More memories, with captions

Dancing Wu Li Master Sitting Buddha

Self Portrait

Civilization?

Casper Eclipse

Casper Eclipse

By Joseph McCabe 8/21/2017

Going to be lots of stories, probably all boring, about people's eclipse experience. I will be looking for something interesting to say. My current position is in the middle of the North Platte River, on an island. It has a projected 2 minute, 28-second total eclipse a few miles west of Casper WY.  I am in a tent, in a jungle, with mosquitoes ready to jump on board if I venture out. Very stinky, having hauled all the camp gear from the river where it was stowed in the kayak. Tried to entice a few of my friends for the journey, one was "a definite" until a lightning bolt hit a historic tree which was threatening his house. Had to do this river trip alone.

Packed up and ready to roll

Kayaking is a lesson in minimalism. You can only take what you really need. Water, food, keyboard, phone...it evolves over time what is important. I have a couple books stowed in dry bags, canned food (which I really don't need), lots of bottled water. A transparent dry bag with small stuff. Me, not being a very organized person, it allows me to practice being more organized. Guess that is relative. I also brought a bulky telescope with a solar filter to use during the eclipse. I have vague memories of a previous eclipse, must have been when I was 14 years old, the age of my son currently is. He has to be in school for this one.

I hear voices floating down the river. Some may be stopping. Hoping that they don't notice the bright red kayak stowed in the long grass upstream on the left side of the island, port. Hard to tell if the people are floating at river speed, or stopped on the island shore. Voices seem close on the right side of the island, starboard.  

Eclipse Viewing Station

Been reading John Nichols, currently On Top of Spoon Mountain, but also, at the same time Milagro Beanfield Wars, the third time for that one.

Last night I slept in my Prius, having been customized for camping with foam board insulation in the windows and a piece of wood extending the fold down seats to almost accommodate my long frame. I have a low wattage inverter which I used to heat water for coffee and cook breakfast this morning. Frozen spinach, slightly thawed; a can of minced tomatoes with chiles and three eggs. Maybe the unused eggs and cheese in the tiny ice chest will still be good tomorrow when I get back to the car. That will be accomplished by riding my bike about 15 miles after having floated down the river. Things of value will be put on the bike, and I will try to lock the kayak somewhere inconspicuous, kind of like where I locked the bike. IF the bike isn't there, I will hitchhike or look to see if Lyft works back to the car upstream. It will all work out. Everything always works out when you think about it. You made it this far. I made it this far. Things are starting to fall apart, mostly my body as should be expected. Medical technology will come to the rescue when I am ready.

Purchased some powdered instant coffee for the kayak trip. I make sun tea in plastic water bottles, 16.9 oz. Take the label off, open, drink a tiny bit, stuff tea bag in, put the lid back on, put in the sun. In a little bit of time, the water is still clear, but if you shake the bottle, the tea color will diffuse. And a little bit later in the sun, it will be a good tea.

Drinks, solid fuel stove.

I am very careful to go in and out of the tent as quickly as possible, but a mosquito snuck in. Luckily I was able to catch it before being bitten. About 4 bites so far, at least one last night and another few this morning. I put the bug juice on. They love my smell and blood.

Just finished the John Nichols book Spoon Mountain; couldn't help but notice some similarities. An older man trying to do outdoors things on his own.

I am muddy on the legs. My shoes will be thrown out after this weekend. They sink into the mud to reveal a black layer of goop below, which proceeds to get on everything. Some mosquitoes have snuck into the tent and bitten me. I was naked except for shorts but now have a shirt, hunter orange just in case any WY white supremacists mistake me for a bear in the middle of the river. I continuously check the kayak to see that it is still there, wasn't discovered by other floaters, and I tied it to some stalks of plants that I hope have some roots to hold the boat if the river rises. Not much chance of that, except for the black storm clouds on the horizon. Preparing for rain. My tent is high on the island, about 5 feet, but flash floods you know....

I have a tunnel of a path leading to my tent from/to the kayak. Thick 20 foot tall weave of one-inch diameter plants. The kayak in the tall three-foot high grass about 20 yards away. By the sound of it, the island is probably only 50 yards wide. There are three paths around this point in the river, mine being on the left, and towards the end of the spit of an island.  Listening for any ruckus or commotion. People have been floating by all day, perhaps 20 or 30 times. My ears can't hear too much, but the tent is pointed towards the boat in case there are any sounds like a kayak being dragged away. It is hidden in tall grass. I can clearly hear people talking on their journey down the river.

I stowed the dirty cutoff pants and my Grateful Dead shirt which was drenched in sweat earlier. Also, the sensitive telescope gear was put into the same dog food bag for water protection. Will it rain? I didn't bring the sleeping bag to save space in the kayak using the previous night temperature as a guide to tonight's requirements. But you never know do you?

Waiting for the eclipse. Hiding from the authorities. But I heard they aren't enforcing too much because of all the people. I am very close to the BLM land. And the river has public access on both sides, so the center is (must be?) also public access.  

My plans are to wake up in the morning, put the telescope together, make a good breakfast on the rocky shore. I have some solid fuel and cook-kit that can heat up some canned food. Plus the instant coffee. Addicted again. Starting new messages with cut and pasted content from other writing. Worried about losing off-line edits.

What is it about the eclipse? It is free. No corporate sponsorship, yet. Anyone can view it with a piece of paper pinhole viewer, or for a few bucks, some special glasses (that aren't counterfeit). For me, I have the solar filter for my telescope, which I hope is ok to use with the magnification of an eclipse. I know it is fine for the sun, for which I love to view the sun in real time. Well, the time it takes the sunlight to leave the star and reach my eye, 8 minutes and 20 seconds?

The eclipse is a great lesson in math. The known paths of the objects spinning in space, moon, earth, sun, and how every so often a thing one 400th the size of the sun, 400 times further away from the sun than it is from the viewer, will match up perfectly on parts of our globe.

Lost lots of good story content because of my lack of internet signal. Subjects about not having a "Trump fuck-up's" news feed. About the river, the birds, the lack of people, isolationist. How filming the leading edge of the eclipse looking down at earth from a plane would be interesting, seeing all the people looking up, worshiping the sun, the moon, and earth dance as they lineup once in awhile. Lining up children so they can view the lining up of the celestial bodies. An extraterrestrial looking down on the spectacle would think we are worshiping the dance of the celestial bodies in space.

Darn, some good writing was lost. Will try to find it when I get to some kind of signal. Good to have no signal, not good that I wasn't able to save that content. Yin and yang. I had also written about a bee and if it will think it missed a day from light to dark to light again. Did it miss seventies, or elevensies? I had blasted the bee off my pants with a toxic breath from my stinky mouth and it was resting on the tarp for 15 minutes putting its body back in order. Dazed.

One motor boat traveling upstream, one raft with three boys, who met up with two other larger boats downstream after the island. One cloud in the sky heading this way. Can't find the moon and it is 40 minutes away. Ate some beans. Thorny plant got my finger as I tried to remove it so the solar panels so they would work best. Survival of the fittest.

Thinking about meditating on the clouds. One exercise is to dissipate clouds through meditation. Wonder if it works for personal reasons? Just sitting in the shade, waiting for the eclipse to shade.

Lots more planes, private small planes in the air than I would have expected.

The eclipse will have started in other places by now. I have a half an hour to go and am looking up. Perhaps there will be a shadow coming towards me like the start of a rain storm. How fast are these bodies moving towards each other? The shadow passes over WY starting at 11:36 and ending at 11:48. Not much time. Tthe Moon’s shadow (also called the “Umbra”) is moving 2,410 mph in Western Oregon, 1,747mph in central Nebraska, 1,462 mph in Western Kentucky, and 1,502 mph near Charleston SC. Will the winds change?

Panorama of riverscape.

The next day.

The actual eclipse was short. Even though I had the telescope set up, I didn't notice the start of the eclipse, was waiting for the time of the total eclipse. But the moon crossing over the sun, then totality, then going away from the sun takes some time. I thought the light changing was due to a tiny cloud, but the light turning orange was the start of the eclipse. I sent my sister a txt msg to be on the lookout for the beginning because she was also in the path of the totality. The most unusual thing I noticed, which may be different from the mountains of other eclipse observation was the mosquitoes. Man, they started biting. I was in the wind, near the river for a few hours with no problems. As soon as the sunlight began to dim they were out in full force. I splashed myself with some bug repellent but was wondering if I should have some Deet. Nasty stuff, but it works. I watched as the moon covered the sun, and as it was completely covered through the telescope, I started my timer. In doing so, I inadvertently hit the scope and was no longer pointing towards the sun. You can't position the scope if you aren't able to see the sun, it was completely black to this particular filter. So I used the time to figure out when to refocus the position, and at a couple seconds past the time that was supposed to be the totality I was able to get a sliver of light back in the telescope viewfinder. During the passage of totality, I did sneak a peek at the sun and saw a ring of light. These are the wavelengths that are bad for your eyes and didn't show up in my viewfinder. In my scope, the sliver of light disappeared on the bottom of the moon, then reappeared on the top, probably all reversed due to mirrors and optics. Some bold mosquitoes were still attacking me during the passage of half to half eclipse. This must of been their sevenses or elevensies (Pippin: What about elevenses? Luncheon? Afternoon tea? Dinner? Supper? ) It was good to be in the path of totality, but a lot of work for a little bit of time in the dark.

Begining of eclipse

Panorama during total eclipse

The work for the trip was much more than I had expected. I packed up everything and enjoyed a kayak down the river to a point a few hours downstream when I thought it would be good to check the map. What, it looks like I passed Casper. Is it possible I went the wrong way? I took the boat out of the water at the next safe location, a ramp near a park in a residential area. Hid bags I didn't want to be stolen and pretended to lock the kayak to a metal pole, but all I really had was cables. The locks were at the bike which I hoped would still be there. And I hoped this additional time will not cause my car to be towed. Carrying the most valuable stuff and bike gear I would need I began to walk out onto a neighborhood road to hitchhike. Wearing my highway yellow with the reflective vest I was immediately able to catch the next car and discuss, "Where the hell am I?" to the conservative gun toting maxi-cab pickup driver. He let me get in and was trying to bring me closer to Casper. But it turned out that my map was upside down. So after about a half a mile, he turned around and brought me back to my kayak. Then I floated further after helping a couple other conservative fisherman load their raft onto their trailer. My pay-it-forward actions. This all took at least an additional half an hour in the hot sun.

Here is a one minute video of the float with a few of the birds: https://goo.gl/photos/GWaTWy1UKg6tBALU8 . It didn't take me the four to five hours to get to my bike as the driver had indicated. It took about two more hours. Nice float, constant paddle, but I was tied up in worry about time and gear. The whole scenario of what to take, where to put it in the packed kayak, or car. And how to take valuable stuff on the bike, back to the car and how to stow the kayak, with stuff that could possibly be stolen, even though it was eventually locked, it was all a mind/organization nightmare. Wish I had taken a picture of the loaded bike with the Werner paddle bungied to the bike cross bar and horizontal paddle breaking the wind.

The trip had its challenges: mosquitos, WY White Supremacists, missed directions and not enough sleep. I should have used one of my tarps as a sleeping bag the night spent on the river. I didn't bring my sleeping bag on the river because I thought it would be warmer than it was. Plus, I was worried about flash floods that whole night before the eclipse, seeing as I was camped out on an island in the middle of the river and then thunder started.

When I started biking, I went the wrong way, should have updated the location, at least 90 degrees F heat; again death by GPS. So I went up up up a hill, which I didn't need to go up, and it added a few miles to my already long heavy bike ride. Lots of other hills between me and the car. But I made it back to the car. There was a nastygram on the windshield, something about no overnight parking; but the day before all kinds of people were there overnight. Anyway, I got all the stuff managed. And will be more attentive on the maps of the future; saving edited text and maps offline.  

The drive back to Colorado was at least an hour longer due to eclipse traffic. I was at the tail end of the traffic; I could stop, rest and miss the stop and go if I timed it correctly, which I did eventually at Fort Collins. Half hour of traffic showing on Google Maps disappeared because I waited and then drove slower to miss the 20 mph slow downs.

Oh yeah, I forgot to mention that it was my birthday, the day of the Casper Eclipse. I've had this eclipse on my calendar for quite some time, many many years. The next one is in 2024, not on my birthday.  Great to have made it this far, 57 years. Have to remember the good stuff. Like the good person who picked me up and turned me back around and the 35 extra years which I didn't plan on.

$15 Streaming Audio for Cars

I've already written a few Raspberry Pi audio blogs which include:

• Introduction (Hardware, Software, Energy)
• $5 Music Box Server
• Rpi Zero w/ Two Different Inexpensive USB Audio Cards
• Rpi with Supstronics x400 HAT
• Grateful Dead Playing in Parks

This blog is a follow-up to the USB Audio Cards blog. Here I evolve the discussion into using the Raspberry Pi W and one of the inexpensive, but good, USB cards. The W version has onboard wifi. I use it as an access point to interface with my phone over hotspot wifi which also provides the system with internet radio.

I have soldered the USB audio card terminals directly to the Raspberry Pi W board as shown in the below photo. A piece of paper is used between the two boards to help reduce any improper touching of the boards.

USB audio card soldered to Raspberry Pi W.

Raspberry Pi W with power cable and blue audio jack

Using my Android phone, I enable the hotspot before turning on the car. Then I can use a hotspot manager on the phone to find the IP address of the Raspberry Pi W and interact with the music software. I use Moode Audio. The latest version costs $10 but an older version is still free and works just fine. I have many albums ripped to FLAC format on the SD card which are accessible by the software from my phone. The software also allows for internet radio in very high-quality format (for example Groove Salad). This project was specifically designed to fit into a tick tack box as shown in the below photo. $15 covers the cost of the two boards.

Tick tack box used to house the device.

The box fits just below my car stereo's and the short yellow audio jack goes from the project into my car stereo auxiliary input on the front of the car stereo. The USB power is supplied by the car through an adapter. With my phone, I control the music playing through the auxiliary input, streaming internet stations or my own library of high-quality FLAC audio files.

The project installed under car stereo into aux jack.

Hope this is an interesting project for those Raspberry Pi tinkerers. 

Good audio document https://www.raspberrypi.org/blog/how-to-play-sound-and-make-noise-with-your-raspberry-pi/ 

Grateful Dead Shows Streaming to Parks

Grateful Dead Shows Streaming to Parks

INTRODUCTION

I was a digital audio taper of live music performances for about 10 years, 1995 to 2005. A songcatcher (read Mickey Hart’s book of that title). Instead of attending Jerry Garcia’s funeral I purchased my first DAT deck and started digitally copying live shows as well as recording live performances. Archive.org has eliminated the need for that taper trading community, it was fun while it lasted. I retired my large DAT deck at the soundboard in Winters California at the Palms Playhouse where it probably caught some more good recordings from 2006 to 2010, or maybe longer. Still have a portable Sony DAT deck.

This past February I was invited to present at the Grateful Dead Scholars Conference held in Albuquerque. Good to meet all the people continuing the culture, but I was a little out of my element surrounded by academics. My presentation was on the collective consciousness of the audience and musicians. Most deadheads will understand this concept quite quickly.  IF at all interested please don't hesitate to request a copy of my academic presentation.

SOLAR POWERED MUSIC PROJECT

I am writing this blog because of a project I have been working on for sometime. It waxes and wanes but at the heart is a continuous stream of Grateful Dead music for any location. Technology is enabling the low cost, high quality sound to be amplified and presented in a solar powered package. Here are some of the components:

1. Archive.org like file access to a full dead show, ideally lossless quality

2. Raspberry pi computer to serve files

3. Low cost relatively high quality Digital Audio Converter (DAC)

4. Relatively low cost good amplifier and speakers

5. Way for community to select a show

6. Solar powered.

I have been experimenting with many different audio scenarios and think I am on the verge of one that makes sense. It is a DAC HAT that has an amplifier on top of a Raspberry Pi (Zero, Pi2 or Pi3) running a Linux OS and music serving software that is accessed by a cell phone like Moode Audio. The gizmo isn't as important as the vision. My vision is for Golden Gate State Park, or any park, to have tree mounted speaker systems that can play a show. Alternatively, Bluetooth output could be multicast to anyone with headphones who then could listen into the show simultaneously with others in the area.

I wanted to host an example of an audio box that plays grateful dead concerts. They played some 2,500 shows, most of which are available online at archive.org. Many of these shows are now streaming high quality versions of the taped shows. In particular, a new form of show is emerging that has mixed audience sounds, soundboard recordings plus taper versions of the shows. These matrix recordings can be an amazing blend of the best aspects of the shows. The hardware/software solutions will lend themselves to any other band hosted at archive.org, etree.org, or an internet radio station. Anything streaming can be now amplified in high quality for low cost.

The current state of development for this concept is below. A 20 watt PV panel, charging a 7 amp hour sealed lead acid battery with a pulse width modulation charge controller. This solar and battery powers the Rpi and DAC HAT with the amplifier to power the sony speakers. The speakers are not weatherproof, so this can not be pole mounted yet. The concept is coming along nicely.

DEMONSTRATIONS

On May 8th 2017 I was able to set up the music at Red Rocks stage and play the 40 year old, remastered version of May 8th 1977. Red Rocks is open to the public as long as there are no performances.

Photo: Solar powered system on the stage at Red Rocks broadcasting the remastered May 8, 1977 Cornell University's Barton Hall Grateful Dead show

I also set up the system near Folsom Field before a Dead and Company show 2017. The music seemed to be a draw for people to congregate around the 40 year old live performance, again May 8th 1977 Cornell Universty Barton Hall Grateful Dead show. Here is a fun publiclly available matrix recording on archive.org https://archive.org/details/gd1977-05-08.111493.mtx.seamons.sbeok.flac16 . The one I was playing is from Rhino, http://www.rhino.com/product/cornell-5877.

Stay tuned to this space as the audio solutions become packaged and tested for the playing of music in the parks.

The evaluation has been broken out into the following audio sections:

• Introduction (Hardware, Software, Energy)
• Blog on the SMSL USB DAC off a RPI 2
• Rpi Zero w/ Two Different Inexpensive USB Audio Cards
• Rpi with Supstronics x400 HAT
• $15 Streaming Audio for Cars
• Grateful Dead Playing in Parks (this post)

And a related post, Uniqueness of the Rpi.

If you have read to this point, check back for updates on solar and actual park experiences. Don't hesitate to contact me if you want to join in the band, energyideas gmail.

Rpi with Supstronics x400 HAT

In this blog posting i am concentrating on combining the Raspberry Pi 2 or 3 with the Suptronics x400 which I picked up for less than $26 including shipping. This has gone up in price and took over a month to arrive. I picked this particular digital audio converter (DAC) because it connects directly to the RPi3 GIPO pins. An external DAC can increase the quality of music out of Raspberry Pi computers because they have better audio components than the low cost Pi components.  The x400 has three different outputs, RCA jacks that can be connected to an amplifier, headphone jack that uses an amplifier circuit and speaker connections for up to 20 watts of amplification per channel. I like that jumpers can be used to turn off sections of the x400 that aren't needed. I also like that it has onboard hardware volume control, even though I typically use the software volume control on the Moode Audio software. The jacks are not of high quality and are attached to the board in a flimsy fashion. This can be modified for anyone wanting a better connection.

Two GPIO pin extender shown, note gap.

Rpi2 with x400 HAT amplified for cube speakers.

x400 Hat on Rpi2 with USB FLAC files, note wires too big for lugs.

Above Rpi2 with x400 HAT running Polk Audio speakers

Moode Audio sets up the x400 Hat quite nicely. Just select the x400 DAC from the list of I2S audio devices, reboot then apply the MPD again. I set the system settings off an ethernet connection including the wifi settings, then reboot and removed the ethernet cable. Then the Moode Audio interactive software should be available on your web browser at the local wifi address and will play the selected music through the x400. You can use the RCA audio output jacks, the headphone jack or connect speakers to the wire lugs. Again, the audio connections on the x400 are a little flimsy so be careful not to break anything off.  

One reason I chose to experiment with Moode Audio is because it has a customization section which includes filter options for the Burr Brown PCM5122 chipset. The x400 includes this PCM5122 chip so you can on the fly change between different digital interpolation filter settings. Some fun discussions on the internet on these different filters (see links below). My old ears can’t tell the diff, but yours might.

Originally I installed the x400 on a Rpi3, then looked at my inventory of Rpi boards and thought it would be better on the Rpi2 with a $3.50 usb wifi dongle. Used an old laptop power cord who’s socket fit the x400 power input. For under $70 US (plus microsd and power supply) we have a system that is portable, low energy consumption, plays and amplifies music quite nicely with an interface off any web browser.  

Update to Rpi3 and Rpi2 discussion now includes using the $5 Rpi Zero. Soldered GPIO pins to the Zero and screwed it to the Suptronics x400 and after two attempts at soldering it worked! 

DAC HAT attached to Rpi Zero.

Wifi adapter and 32 gb sd card on USB, amplifier for two speakers.

Bottom view.

Side View.

Currently running RCA plugs through Carver to power some Paradigm speakers. FLACs sound excellent.

Three variations of Rpi's and DAC HAT.

These systems have been working very nicely with the latest version of Moode Audio software, amplifying the sound to various speaker configurations.

There are some new HATs from Suptronics which promise to provide affordable sound from Rpi integration. New boards and kits can be found at this web address: http://www.suptronics.com/ My own work is focusing on the x5000 series for solar powered music solutions. Stay tuned to this and other blog entries listed below for any updates. 15 second video of solar powered Suptronics HAT system: https://goo.gl/photos/w775JvDVJfxWM1YSA

Further reading:
Search on either Supstronics or Suptronics, it is out there under both names.

There are some foreign language websites that can be translated by google translate which have some interesting content too. Here are some links to other x400 content:

http://www.suptronics.com/Xseries/x400.html

https://twistednix.wordpress.com/2016/09/26/hifipi-part-2-the-basic-build/

https://www.hackster.io/FunguyPro/how-to-use-supstronics-x400-expansion-board-68f956

http://feedlifehack.com/suptronics-x400-how-to-receive-a-good-sound-for-24-dollars

X400 DAC filters:

http://archimago.blogspot.com/2016/10/measurements-hifiberry-dac-pro-pcm5122.html?m=1

The evaluation has been broken out into the following audio sections:

• Introduction (Hardware, Software, Energy)
• Blog on the SMSL USB DAC off a RPI 2
• Rpi Zero w/ Two Different Inexpensive USB Audio Cards
• Rpi with Supstronics x400 HAT (this post)
• Grateful Dead Playing in Parks

And a related post, Uniqueness of the Rpi.

Good audio document https://www.raspberrypi.org/blog/how-to-play-sound-and-make-noise-with-your-raspberry-pi/.