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Jornada 720 USB Host

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joval Page Icon Posted 2021-05-18 6:11 AM
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Hi Stefan!
OK pulled the motherboard...wow, those board contacts the wires are soldered to are really really tiny! Time to get the dissecting microscope out... to get a closer look.

I see the Jlime repository was a big help.. he got so close to success, but no cigar. Was the reduced clock rate the key to success??? Yes I see the capacitors leads are an easy source for the +5v and ground.

Will be checking out the chip schematic soon...resistors, etc. Should be much easier to do than soldering those motherboard wires. Presently waiting on the chip Max1607 I think...

Did you actually get the usb wifi dongle to connect to a router??? This is exciting stuff and great that you can help with the drivers!

Keep up the good work!

joval

once again posted on one of my J720/Devuan/RasPi3 "Hybrids"
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_dev-null Page Icon Posted 2021-05-18 7:32 AM
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Hi!
Yes I connected to a router - with an Edimax EW-7811Un Stick (the only one I had and one of the crappiest out there). So I stick with the PCMCIA card - and I can use the USB port for other stuff.

Be sure to use a soldering iron with a fine tip! And if you can use leaded solder because it has a lower melting point. The vias and traces on the PCB dont like too much heat!
Be careful on the backside: try to scratch away the white paint on the vias with a sharp knife. Then its easier to apply solder ...


Stefan
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ntware Page Icon Posted 2021-05-19 1:34 PM
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I wonder what the speed of a USB Wi-Fi dongle looks like, given the USB 1.1 restrictions
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_dev-null Page Icon Posted 2021-05-19 8:21 PM
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Sadly I only have this crappy Edimax dongle and it is slow as hell - even on a USB 2.0 port ...
However I did some speed tests with USB memory sticks - I get around ~1MB/s write Speed. So we come close to the specified speed of USB 1.1 which should be 12Mbit/s.
I think that PCMCIA cards will always be the better and faster option! I try to give the Ambicom WL54-CF a second chance - then it is even possible to connect to WPA2 networks.

Back to topic: I am sure that the initial problem with USB Host is power related - the power draw with the downclocked CPU is about 100-200mA less than with full clock.
If we attach USB devices that draw more than ~500mA then the PCMCIA slot gets shut down and the USB host controller dies - sometimes there are even write problems to the CF card (maybe it resets the whole SA1111 chip because it is also responsible for PCMCIA and CF).

The same thing happens if we try to overclock the CPU to more than 220MHz in Windows - the PCMCIA slot gets shut down and the CF card isnt recognized anymore.

The Jornada 720 uses a 1LTC1143 chip to regulate the 5V and 3.3V. I will have a look which MOSFETS are driven by it. So we can get a clue how much power can be delivered from the supply circuit!
There are rumors that the power circuit has been redesigned on the J728 - if I get my mainboard back I can verify this!

Regards
Stefan
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joval Page Icon Posted 2021-05-19 11:51 PM
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_dev-null - 2021-05-19 12:21 PM

Back to topic: I am sure that the initial problem with USB Host is power related - the power draw with the downclocked CPU is about 100-200mA less than with full clock.
If we attach USB devices that draw more than ~500mA then the PCMCIA slot gets shut down and the USB host controller dies - sometimes there are even write problems to the CF card (maybe it resets the whole SA1111 chip because it is also responsible for PCMCIA and CF).


Regards
Stefan


Stefan... That is a great explanation as to why downclocking works! Really makes sense... always amazed and pleased you figured this out. Is that with or would a 32Mb ROM card instead of 64/128Mb make any big power difference so as to help matters??

How about running the usb port from externally powered usb hub and share grounds between the J720 and the hub, maybe with some small resistance load on the J720 side if needed for sensing/turning on usb tx rx data transfer.
===============>>>>>>>>>>>>
OK, the Chips and resistors just arrived!! They are tiny..itsy bitsy. I will practice technique on an old PC network card then the J720. Now, I have to locate the low temp solder Rich clued me in on and I bought on Amazon. Wish me luck!

It will take me a few days I suppose, if it works I will try the edimax "micro"-dongle I have ... including running off external hub with grounding...that should take the load off the motherboard. I hope!

Does edimax require a new driver...its linux compatible (RasPi). Maybe I can take the RasPi driver and load it on the J720... if I knew how to do that! Thanks for the help and guidance!

joval

posted from my J720/Duvean/RasPi "contraption"

Edited by joval 2021-05-20 12:02 AM
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joval Page Icon Posted 2021-05-21 6:05 AM
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Stefan:
OK, all 4 motherboard leads are soldered in place, I used enameled wire that fit into the mobo contact holes (a bit thinner than cat 5 cable wire. Used a fine tip soldering iron and lead solder as I couldn't local my low temp solder, tried to redo one lead under the rom card and the solder pad came off , too much heat and fiddling around...however easy fix was to use the contact hole next to it as they were connected by a thin trace wire. I slipped some colored insulation from cat5 cable wires over the enameled wires for extra protection. Removing the Pcmcia slot cover wasn't too bad, but locating the proper place to solder the leads was difficult to see from Stefan's photo or even the JLime photos. I'm including what I hope is a high res photo with better detail. I removed the resistor as shown but found that the 10K SMD resistors I purchased were way tooo small, so I cannibalized a slightly too big one from an arduino mini clone and made it work... although it doesn't look too pretty. so SMD size would be helpful to know. I managed to break off the mini microphone so need to replace that or live without it. All the soldering was done using a dissecting microscope that's been sitting idle many years... I don't know how it can be done without that level of magnification, IMO.

I'm stopping here now, I could sure use some help...mainly a detailed list of components... I thought I only needed the Max1607 but there is another chip, resistors, capacitors, and chokes. Please, could really use some help with a detailed component list!!!! I need to know what to order so I can have them group shipped... a schematic isn't really adequate. Otherwise shipping costs get way out of hand. Again SMD exact size would be nice!! Thanks in advance.

Here's my picture pcmcia side, with the mangled but functional oversized replacement 10K resistor shown. It's hi-res so you can really zoom in (unlike previous potos).This is tricky stuff IMO, but not impossible!





Edited by joval 2021-05-21 6:26 AM




(MoBo_USBJ720.jpg)



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Attachments MoBo_USBJ720.jpg (1719KB - 1 downloads)
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_dev-null Page Icon Posted 2021-05-21 9:15 AM
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Hello!
You need:


SMD-Resistor, 1206, 24 Ohm, 250 mW, 1% - 2pcs

SMD Tantal, 100 uF, 6,3 V, 2000 h, low Profile - 2pcs

SMD-Resistor, 1206, 15 kOhm, 250 mW, 1% - 2pcs

EMI Suppression Filter SMD1206 BLM31 50 Ohm - 2pcs

You can also wire up the SN75240 for ESD protection - I havent wired it up yet ... USB works without it but the SA1111 can be damaged due to ESD coming through USB cables/devices.
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joval Page Icon Posted 2021-05-21 3:29 PM
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_dev-null - 2021-05-21 1:15 AM

Hello!
You need:


SMD-Resistor, 1206, 24 Ohm, 250 mW, 1% - 2pcs

SMD Tantal, 100 uF, 6,3 V, 2000 h, low Profile - 2pcs

SMD-Resistor, 1206, 15 kOhm, 250 mW, 1% - 2pcs

EMI Suppression Filter SMD1206 BLM31 50 Ohm - 2pcs

You can also wire up the SN75240 for ESD protection - I havent wired it up yet ... USB works without it but the SA1111 can be damaged due to ESD coming through USB cables/devices.


Thanks Stefan that's a big help!! Obviously there is a learning curve here... enamel wire seems easiest to me then add insulating sleve. Are the ferrite chokes needed??

(Sorry about my moaning and groaning ...if that oozed through in my last post... I felt like an disturbed cannibal stealing the heart out my arduino victim so that the Jornada could be reincarnated with USB... just joking).

If I get things working correctly I will write it all up in detail.... save others some missteps. If you agree, I would like to add it to your site to save you the extra work and help others bold enough to take this project on (much as you host the Jlime section). Or suggest another option if this is not realistic, or verboten!

joval

(posted on my J720/Devuan/RasPi hybrid)

Edited by joval 2021-05-21 3:51 PM
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joval Page Icon Posted 2021-06-02 4:41 AM
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_dev-null:

Realize I've already done the hard part with the wiring... and will be much easier to do a second time having the right wire and resistor size and knowing the layout.

I will review the schematic for other parts, overload chip, etc and soon order them all. Also, I want to look at a plug-in PCIE express usb card for any clues( update: found one with mislabeled parts, see below), then get back on the trail.

Seemed to me looking at the input pins on theESP8266 (arduino clone) maybe they use opto-isolators to avoid voltage spikes/circuit overloads. Could be another rabbit hole though...

regards,

joval



Edited by joval 2021-06-02 4:54 AM




(usb-pcie_.jpg)



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_dev-null Page Icon Posted 2021-06-02 9:37 AM
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Factorite (Elite)

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Hi!
The ESP8266 uses an USB-RS232/UART (some sort of FTDI chip) converter for communication. This is completely different because it is a USB device and not an host controller.

PS: The picture attached is marketing at its finest - they marked the inductors as capacitors and vice versa ... if you are really interested google for USB host controller design and have a look at sample schematics.


Regards
Stefan
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joval Page Icon Posted 2021-06-02 5:48 PM
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_dev-null - 2021-06-02 1:37 AM

Hi!

PS: The picture attached is marketing at its finest - they marked the inductors as capacitors and vice versa ... if you are really interested google for USB host controller design and have a look at sample schematics.


Regards
Stefan


Well said my friend... yet, quite good for a laugh!!

I had to give my brain a rest after my initial attempt at wiring things up, but wow, now the schematic and components all make sense. Your component list is great! I see the EMI filters, and need "3 "100uf capacitors according to schematic. Thanks for that!!!

In fact, I have an idea worth considering/trying that may really simplify things:

Eliminate the need for the power sense and power control wires, and the MAX1607 switch and instead use a (cheap) external 5 volt power source/inverter board with common ground to capacitor on motherboard (that could be powered by the J720 12 volt charge port or docking port 12v with a manual switch perhaps).

If this works, wiring could be easy, requiring only 2 data lines and ground wire (to the capacitor). Still need to change out the 10k SMD resistor though and remove pcmcia cover, etc. How important is that resistor change, critical??? Anyway, worth exploring! At least until parts arrive...

Since USB Transient suppression is optional ( requires the SN75240 chip and 15k ohm resistors) at this prototyping stage, only the 24 ohm resistors are needed and a 5volt power supply/inverter/or "wall wart ( by tapping into a USB "extension port" cable for ground and +D -D)" I will give it a try, wish me luck!

Cheers!


joval

Edited by joval 2021-06-02 6:11 PM
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