DreamPi on Raspberry Pi Zero W?

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pelvicthrustman
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Posts: 15

Re: DreamPi on Raspberry Pi Zero W?

Post#11 » Sun Jan 07, 2018 5:29 pm

@kazade

There are known issues with the RPi Zero W wifi driver (NTP for example is busted without using tcpdump to correct some packet-level issues). Once the driver is fixed the tcpdump process won't be required (it isn't when using other WiFi adapters), but until then Band-Aids are what we've got to work with.

As for the 5637 it's a CDC-ACM device so no drivers required - the major thing that makes it incompatible with DreamPi is that it acknowledges the ATA command with "OK" before issuing "CONNECT", causing DreamPi to try to setup the connection with pon before the modem is ready. Simply making sure to check the ATA output explicitly for "CONNECT" fixes the issue and allows it to work.

One other thing - I've done my own dedicated RPi firmware development before (http://psx-scene.com/forums/f19/how-bui ... s2-127728/) but I used buildroot to cook up a custom Linux, which makes updating to support the latest Kernel/driver fixes super simple and allows for extremely low boot times (4-7 seconds depending on installation method) and drag and drop firmware updates (longer boot times but no need for EXT partitions). Would you be interested in moving DreamPi to a Buildroot platform? I could probably do all the heavy lifting, I'd would just need to know exactly what needs to run for any services beyond dreampi.py/pon. Just an idea :).



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pelvicthrustman
rebel
Posts: 15

Re: DreamPi on Raspberry Pi Zero W?

Post#12 » Sun Jan 07, 2018 5:46 pm

@Anthony817

The Zero was actually $5, the Zero W is $10, and with Adafruit shipping it doesn't end up being far away from the eBay going rate of $16 free shipping at the moment.

The 5637 on the other hand is around $40 on eBay atm (or can be bought for around $50 from other online stores). They appear to have gone up in price since I bought a few for ~$30.

The voltage boost board is $7.76 on Amazon, and the other parts (PCB, cap resistor, diode, wire, solder) can all be had for about $2. A suitable MicroSD card would be at least $5.

The total price then is ~$71 in parts, USPS shipping is ~$7 in the USA so total ~$78 without labor. Depending on how cheap someone is willing to put these together I can't imagine one costing less than $100 shipped. I definitely wouldn't go through all that trouble for $22, but maybe someone else would.

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Anthony817
Shark Patrol
Posts: 4009

Re: DreamPi on Raspberry Pi Zero W?

Post#13 » Thu Jan 11, 2018 12:19 am

Thanks for the info! Still looks like the best way to do it imho. Clean as hell too.
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The-Amazing-Mr_V
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Posts: 821

Re: DreamPi on Raspberry Pi Zero W?

Post#14 » Thu Jan 11, 2018 6:20 am

That is a clean set up and it almost matches the dreamcast color!

Sunoo
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Posts: 5

Re: DreamPi on Raspberry Pi Zero W?

Post#15 » Fri Mar 02, 2018 11:21 am

pelvicthrustman wrote:I ended up just creating a simple service that runs tcpdump specifying all source and destination packets from the DC's IP and dumping output to /dev/null which works like a charm. It seems that just having tcpdump running alters the Zero W WiFi driver's behavior in such a way as to fix whatever the problem is.


Could you share this service? I'm in the middle of getting a Raspberry Pi Zero W set up for this purpose as well, so it'd be nice to not have to reinvent the wheel.

Rappolt
shadow
Posts: 7

Re: DreamPi on Raspberry Pi Zero W?

Post#16 » Sat Mar 31, 2018 12:51 am

pelvicthrustman wrote:@Anthony817

The 5637 on the other hand is around $40 on eBay atm (or can be bought for around $50 from other online stores). They appear to have gone up in price since I bought a few for ~$30.

The voltage boost board is $7.76 on Amazon, and the other parts (PCB, cap resistor, diode, wire, solder) can all be had for about $2. A suitable MicroSD card would be at least $5.


If you're using an RPZ or RPZW, don't forget a straight USB OTG adapter/cable. I had to make one, scavenging a cruddy USB wall wart's female USB A, because I could only find my 90° OTG cables and it blocked the power input...

I found a few USB modems that will hopefully work on Amazon for $10-15, but they seem to only have the center two pins. They're also too small to fit anything more than just the boost board and its own board inside. Good thing I have a 3D printer to make a big case to unify the RPiZW! ... Or velcro.
I did my mod, I'm just trying to get my DreamPi working on a RPiZW to test that modem. I'll follow up if the $12 modem works.

Good news is that you can pick up boost boards on eBay for about $0.75-1.50 each.

An interesting idea I had was to use an 18650 and a USB-powered 3.7v charger board to make it battery powered. You can get unprotected 18650s for around $4 on Batteryjunction and the charger boards for $0.70-0.40 apiece on eBay. You hook up the leads according to this picture: https://goo.gl/CSvpsS
You'll want a carriage for the battery and 2 batteries and/or access to the Micro USB for charging or constant power without a battery.

If the cheap modem works, that'll drop the price a solid $15, and another $6 from the boost converters. I'm about $60 in to my project, so $100 shipped would be absolutely worth it, and I'm a poor college student. Even $120 would be fair. And maybe a +$20 battery powered model.

I really know nothing about Linux and don't have a second RPi to update the OS. It sucks, but I'm really depending on you releasing those files and guide. I'm relieved to know this community is so active!

As a side note, does anyone know where I can pick up a good XV779 GD-ROM controller board? I bought one from Squeept on eBay, but it was even more broken than my broken one. They both boot, and I've got all the stuff for an IDE mod, I just want to have a fully working GDR drive.

pelvicthrustman
rebel
Posts: 15

Re: DreamPi on Raspberry Pi Zero W?

Post#17 » Sat Mar 31, 2018 4:22 am

@Rappolt

You don't need an OTG adapter, straight or otherwise - as seen on the pictures you can simply solider the USB D+/D- and +5/Gnd connections to the large pads conveniently placed on the bottom of the RPi Zero W for pogo pin connections.

As far as eBay boost boards from China - I've used them, they can work sometimes, but they can also fail miserably - the U.S. sourced ones are overpriced for low volume orders but are reasonably good quality and available quickly. If you were going to buy some cheap ones I'd recommend getting a +12v boost circuit since a +9v boost will not provide sufficient voltage after the diode drop is factored in.

As far as modems go - soft modems are quite cheap but require drivers which are generally only available for 2.6.x Linux Kernels (at least for the chipsets I've seen) due to the age of the hardware. If there's a very cheap soft modem with drivers compatible with 4.x Kernels that would be ideal, but any way you slice it the 5637 is better, being a hardware modem and since the parts can fit in the existing case there's no need to 3d print anything.

I will try to find some time this weekend to upload the firmware - please keep in mind though that simply attaching a software modem will probably not work without any modifications (or perhaps at all depending on driver availability) - you'll need to do some research to find a good chipset and then of course make sure that it presents itself as /dev/ttyACM0.

Rappolt
shadow
Posts: 7

Re: DreamPi on Raspberry Pi Zero W?

Post#18 » Sat Mar 31, 2018 5:27 am

@pelvicthrustman

The OTG adapter is mostly just for testing, since I didn't want to molest the board until I'm ready to assemble the final project.

I understand not wanting to use cheap parts. I refuse to on my car.
Those sound like some hefty diodes you're using, since I wouldn't expect anything this low power to have a drop larger than 100mV. My drop was less than 20mV.

I'm seeing what you mean about doing research, and I'm already drowning, haha. All I can find is 2.6, like you said, and I don't know how to recompile drivers, let alone how to fix any issues between versions. This is my first time ever touching Linux without a GUI.
PcWzrd's preferred Dell nw147 uses a Conexant chipset, like the cheap software modems do, so it's possible the Dells are software modems too, but I really don't know.
Edit: It's definitely different, and the nw147 is a hardware modem.

From what I've read, a software modem should report as /dev/tty/USB0 - which would denote that it's the responsibility of the system (RPi) to process (idk what), but if it were a hardware modem, it would report as ACM, because it is the modem device doing the processing.
There's an outstanding chance I'm wrong.

Sounds like I'm out $12 on the wrong modem. Could be worse.
Edit2: I'm purchasing a USR5637, as well as 2 different $18 nameless modems that claim to be hardware modems. If the nameless ones work, I'll edit this post and link them here. One will show up Apr 1, the other will show up Apr 5-10.
The first one worked! $18 on Amazon: https://www.amazon.com/gp/product/B012I ... UTF8&psc=1

I did manage to update and upgrade my RPiZW using a USB WiFI adapter which got it internet access, but it still won't detect its own BT/WiFi hardware, even with ifconfig -a.
Dreamcast.online/now also doesn't detect My DreamPi, even when I manually state its local IP, and I've even cleared it in DMZ. I don't think the lack of functioning modem should really affect that part.
Last edited by Rappolt on Tue Apr 03, 2018 1:25 pm, edited 1 time in total.

pelvicthrustman
rebel
Posts: 15

Re: DreamPi on Raspberry Pi Zero W?

Post#19 » Sat Mar 31, 2018 11:40 am

Rappolt wrote:@pelvicthrustman

The OTG adapter is mostly just for testing, since I didn't want to molest the board until I'm ready to assemble the final project.

I understand not wanting to use cheap parts. I refuse to on my car.
Those sound like some hefty diodes you're using, since I wouldn't expect anything this low power to have a drop larger than 100mV. My drop was less than 20mV.

I'm seeing what you mean about doing research, and I'm already drowning, haha. All I can find is 2.6, like you said, and I don't know how to recompile drivers, let alone how to fix any issues between versions. This is my first time ever touching Linux without a GUI.
PcWzrd's preferred Dell nw147 uses a Conexant chipset, like the cheap software modems do, so it's possible the Dells are software modems too, but I really don't know.
Edit: It's definitely different, and the nw147 is a hardware modem.

From what I've read, a software modem should report as /dev/tty/USB0 - which would denote that it's the responsibility of the system (RPi) to process (idk what), but if it were a hardware modem, it would report as ACM, because it is the modem device doing the processing.
There's an outstanding chance I'm wrong.

Sounds like I'm out $12 on the wrong modem. Could be worse.
Edit2: I'm purchasing a USR5637, as well as 2 different $18 nameless modems that claim to be hardware modems. If the nameless ones work, I'll edit this post and link them here. One will show up Apr 1, the other will show up Apr 5-10.

I did manage to update and upgrade my RPiZW using a USB WiFI adapter which got it internet access, but it still won't detect its own BT/WiFi hardware, even with ifconfig -a.
Dreamcast.online/now also doesn't detect My DreamPi, even when I manually state its local IP, and I've even cleared it in DMZ. I don't think the lack of functioning modem should really affect that part.
http://en.wikipedia.org/wiki/Diode

"In a small silicon diode operating at its rated currents, the voltage drop is about 0.6 to 0.7 volts. The value is different for other diode types—Schottky diodes can be rated as low as 0.2 V, germanium diodes 0.25 to 0.3 V, and red or blue light-emitting diodes (LEDs) can have values of 1.4 V and 4.0 V respectively."

You may want to brush up on your basic electronics, common diodes do not have mV range drops. The reason you'll need a diode is that your boost circuit is not an ideal DC voltage source. When you connect the boost's output to one side of the voltage-inducer's in-line capacitor, if there is no diode installed, then the current will flow both into the capacitor and into the boost circuit as the phone line's analog signal changes. Since silicon diodes drop ~0.6v, if you use a 9v boost your voltage will be ~8.4v which will at best get you a very unstable ~14.4k connection. I did some tests on a few configurations while considering different approaches to the DreamPi mod - you can readily observe the destabilizing effects of omitting a diode on the phone line signal using an oscilloscope. Please note that it is also important that you get the capacitor and diode polarities right when constructing the circuit.

Check out my post on this thread for a detailed description of integrating a voltage inducer:
viewtopic.php?f=3&t=10795&p=106743#p106743

As far as Dreamcast Now stuff I've literally never used it - I've never had a need to or interest in setting it up so I can't tell you if my DreamPi firmware broke that.

Regarding /dev/ttyUSB0 - the driver is supposed to interact with whatever internal protocol the modem hardware provides and expose it to applications as a virtual CDC/ACM device (thus 'soft' modem since hardware modems are actually CDC/ACM devices). IIRC it should probably choose to make that virtual device as /dev/ttyACM0 - but I'm not 100% sure. I had a $10 soft modem lying around before I bought my first 5637, so I went ahead and grabbed an old Linux distro, threw it on a VM and manually established a PSO connection through my Laptop when the Dreamcast dialed in. So I at least know that it is possible to use a soft modem, just not on a Kernel version which would work with an RPi.



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Rappolt
shadow
Posts: 7

Re: DreamPi on Raspberry Pi Zero W?

Post#20 » Sat Mar 31, 2018 12:57 pm

@pelvicthrustman

I actually used an LED package, overvolted and burned out the emitters, but it still somehow works as a diode. I'm baffled that it's only a 20mV drop. I don't trust it, so it's only there for testing until I find where I've put my diodes, because they're not in the Diode drawer, haha.

I'm not too worried about Dreamcast Now, I just figured it might have some useful info.

I'll have to check if the soft modem reports as ttyACM or ttyUSB. I quit and turned in for the night before I found an easy way to check.
With lsusb I can see that the soft modem is connected, but with ls /dev/tty* I do not see a single ttyUSB or ttyACM device.
Edit: There is a /dev/ttyAMA0 device, and other people have had their modems reporting under the same type

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