InsertTitle
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Is there a way to monitor the CM3 using USB micro?

Mon Aug 20, 2018 8:39 am

So I've been working on a prototype using the compute module. Board design is in its 1st version and I'm already at work designing the refined 2nd version. During the rework I noticed a bit of issue when it comes to connecting to the compute module in order to monitor its progress. Originally I was going to use wireless on the custom PCB in the form of the ESP_Wroom_32 following this guide which uses the ESP8266 to allow me to perform headless monitoring; however later down the line I realised I won't be needing wireless with my prototype but the bluetooth chip or equivalent that the ESP_Wroom_32 uses and thus have had to look for an alternative option to monitor the Compute module 3. I was thinking as I already use a USB micro to power/recharge the battery, it could also be used an way for me to connect directly to an host computer that could do the recharging but also allow me to access either an terminal or GUI executable and allow me to monitor / modify any scripts.

I saw talks on a previous thread that this could be possible on a RPI model A using an adafruit cable or another form of cable which then allowed the board to be powered whilst simultaneously accessing an serial interface to monitor the RPI; however this is not the solution I wish to use but rather would like to know if there is a way that I can simply use a single usb micro and plug into a host computer and perform a headless connection to allow myself to open a GUI whereby I can monitor/modify the Compute module for troubleshooting.

If this is not possible on just a singular usb micro cable then what alternatives could I potentially look toward minus the ones I've already posted about. Preferably I want to be as headless as possible using a singular cable.

aBUGSworstnightmare
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Re: Is there a way to monitor the CM3 using USB micro?

Mon Aug 20, 2018 1:27 pm

Configure your CM3 for USB Ethernet gadget mode i.e.

Make sure to wire up USB_OTGID pin correctly. If you have an CMIO on-hands you can evaluate before your finalize your carrier board design.

InsertTitle
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Re: Is there a way to monitor the CM3 using USB micro?

Mon Aug 20, 2018 5:27 pm

I see, didn't think of that thanks for the info.
My only other question based off of this information is upon looking at other threads talking about USB Gadget Mode is that you should use the slave micro usb on the I/O and not the power micro. So I'm curious as to if I'm using only a single micro usb in my carrier board design, would it still be possible to use it as a slave port when connecting directly to an host computer when troubleshooting and have it be able to switch to power only when I say plug it into a wall plug?

aBUGSworstnightmare
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Re: Is there a way to monitor the CM3 using USB micro?

Mon Aug 20, 2018 6:57 pm

What do you think why I've mentioned USB OTG-ID?

Looks like you'll need some more readings http://www.usb.org/developers/onthego/otg1_0.pdf

Pin4 on the 'slave' microUSB on CMIO is unconnected, you need to use the jumper for the signal.

There are no D+/D- signals on a USB power adapter. They don't care if you're device is slave or host. Ever charged a mobile phone (Android)? Most of them support OTG.

InsertTitle
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Re: Is there a way to monitor the CM3 using USB micro?

Mon Aug 20, 2018 8:05 pm

aBUGSworstnightmare wrote:
Mon Aug 20, 2018 6:57 pm
What do you think why I've mentioned USB OTG-ID?

Looks like you'll need some more readings http://www.usb.org/developers/onthego/otg1_0.pdf

Pin4 on the 'slave' microUSB on CMIO is unconnected, you need to use the jumper for the signal.

There are no D+/D- signals on a USB power adapter. They don't care if you're device is slave or host. Ever charged a mobile phone (Android)? Most of them support OTG.
Cheers for the readings. Very much out of depth in that section. Atleast glad I got reference point now to go off from.

InsertTitle
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Re: Is there a way to monitor the CM3 using USB micro?

Mon Aug 20, 2018 8:26 pm

Just looking at my CMIO, so let me get this straight I would simply have to use a jumper from USB_OTGID to GPIO pin 4? Or do I simply GND it?

Or are you talking about pin 4 as in J4 where it says EN and DIS?

aBUGSworstnightmare
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Joined: Tue Jun 30, 2015 1:35 pm

Re: Is there a way to monitor the CM3 using USB micro?

Mon Aug 20, 2018 8:42 pm

OMG!
Good luck with your guessing game! Sorry, but I did all I could.

InsertTitle
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Re: Is there a way to monitor the CM3 using USB micro?

Mon Aug 20, 2018 9:08 pm

aBUGSworstnightmare wrote:
Mon Aug 20, 2018 8:42 pm
OMG!
Good luck with your guessing game! Sorry, but I did all I could.
Sigh fed up of scrubs making posts like this. I gather my know how isn't the best when it comes to electronics, I come from a games software background and started taking up electronics just after I graduated uni so still delving into the unknown but this doesn't give me a vote of confidence, if when trying to get a full understanding of answer given by asking questions that people just up and give up on you.

Like that PDF you posted up, read through all 74 pages I understand partially what was mentioned but not fully hence why the extra questions so I could get a better understanding as to what I needed to do in order to achieve the desired result I'm aiming for.

aBUGSworstnightmare
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Re: Is there a way to monitor the CM3 using USB micro?

Tue Aug 21, 2018 5:15 am

Sorry man, but i gave you the information that you need to serve USB OTG ID - pin 168 of the Compute module.

As you did not know what I was talking about I've probided you the full USB OTG spec as a reference.

Then you asked how to do this with your carrier board, and that's the point where I must assume that you either didn't review the provided information (including CMIO schematic) or still don't understand.

Compute modules are intended to be used by professionals, so I need to assume you have a decent knowleadge in electronics. In addtion, it should be clear to you why there are two USB ports on i.e. the zero and the CMIO: you can not connect a standard device (i.e. mouse) while supplying power via the same connector. That's why there is the need for another connector for power only. This 'other' connector can be whatever the user needs/wants!

A USB OTG-device can either supply power to the slave when in host mode (i.e. Your Android phone when you connect a USB stick to it), or it can be powered by the host (as it now becomes a device, i.e. HID gadget).

Sorry, but don' t rant about other users when you don't have propper knowleadge.

aBUGSworstnightmare
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Joined: Tue Jun 30, 2015 1:35 pm

Re: Is there a way to monitor the CM3 using USB micro?

Tue Aug 21, 2018 5:23 am

And keep in mind that a USB OTG port should be using a type AB connector, and that requires correct behaviour of the ID line. The CMIO has only a type B, and no handling of USB ID (pin4 of the slave microUSB connector).
Hence it doesn't have the correct linking back to the USB controller for auto switching.

gsh
Raspberry Pi Engineer & Forum Moderator
Raspberry Pi Engineer & Forum Moderator
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Re: Is there a way to monitor the CM3 using USB micro?

Tue Aug 21, 2018 6:27 am

The CMIO board has a pull down on the OTGID pin, I think this is what I would term a 'bad decision' from my point! R12 is a 1K pull down.

I would suggest removing this resistor, the chip has an internal pull up on it... Then leave the OTGID pin unconnected for device (peripheral) mode and ground it with a jumper for host mode.

Otherwise you can force periph mode in the config.txt so it only works in that mode...

dtoverlay=dwc2,dr_mode=peripheral
--
Gordon Hollingworth PhD
Raspberry Pi - Director of Software Engineering

InsertTitle
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Re: Is there a way to monitor the CM3 using USB micro?

Tue Aug 21, 2018 8:29 am

aBUGSworstnightmare wrote:
Tue Aug 21, 2018 5:15 am
Sorry man, but i gave you the information that you need to serve USB OTG ID - pin 168 of the Compute module.

As you did not know what I was talking about I've probided you the full USB OTG spec as a reference.

Then you asked how to do this with your carrier board, and that's the point where I must assume that you either didn't review the provided information (including CMIO schematic) or still don't understand.

Compute modules are intended to be used by professionals, so I need to assume you have a decent knowleadge in electronics. In addtion, it should be clear to you why there are two USB ports on i.e. the zero and the CMIO: you can not connect a standard device (i.e. mouse) while supplying power via the same connector. That's why there is the need for another connector for power only. This 'other' connector can be whatever the user needs/wants!

A USB OTG-device can either supply power to the slave when in host mode (i.e. Your Android phone when you connect a USB stick to it), or it can be powered by the host (as it now becomes a device, i.e. HID gadget).

Sorry, but don' t rant about other users when you don't have propper knowleadge.
Sorry I don't usually rant but it was just one of those things where I required a better understanding so you should be able to understand where I'm coming from. I already know about the Zero and CMIO with the 2 different usb ports but I wanted things clearing up so I knew what I was looking at because I would using the CM in my own carrier design with sodimm. Don't get me wrong I more or less understood your answer but was asking those questions for further clarification.
aBUGSworstnightmare wrote: And keep in mind that a USB OTG port should be using a type AB connector, and that requires correct behaviour of the ID line. The CMIO has only a type B, and no handling of USB ID (pin4 of the slave microUSB connector).
Hence it doesn't have the correct linking back to the USB controller for auto switching.
Knew about the connectors but not of the USB ID so that's useful to especially when it comes to auto switching.

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