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by scorpia
Tue Jul 16, 2019 9:49 pm
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: Reading AN1/AN2 from MxL7704
Replies: 2
Views: 431

Re: Reading AN1/AN2 from MxL7704

Thanks for that. As the pi doesn't have /sys/class/typec/ support yet I have turned this into a basic script to determine the available Type-C current on the pi, have posted below for anyone else who might find it usefull. #!/usr/bin/python3 import subprocess def getCCvoltage(): vcgenresult = subpro...
by scorpia
Sun Jul 14, 2019 1:46 pm
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: Reading AN1/AN2 from MxL7704
Replies: 2
Views: 431

Reading AN1/AN2 from MxL7704

Does anyone know if there is the capability to read AN1/AN2 on the MxL7704 IC from userspace in order to determine the Type-C current available to the pi. I believe the I2C interface to the IC is controlled directly by the low level firmware so would assume there would need a vgencmd function to rea...
by scorpia
Fri Jul 12, 2019 11:34 pm
Forum: General discussion
Topic: I didn't think the usb c power thing was a big deal...
Replies: 92
Views: 5590

Re: I didn't think the usb c power thing was a big deal...

There are quite a few clickbaity articles on this topic now (and a large amount of other add revenue farming articles as well based on my received word-press pingbacks), I started to see quite a few of them once techrepublic and other tech news sites featured the story (was amusing to see my google ...
by scorpia
Thu Jul 11, 2019 9:44 pm
Forum: General discussion
Topic: Charger compatibility with the Pi 4 (Single Type C CC resistor on Pi4)
Replies: 28
Views: 5208

Re: Charger compatibility with the Pi 4 (Single Type C CC resistor on Pi4)

@jamesh, Is there going to be an announcement when a version with the fix is released or is there somewhere where I can subscribe to notifications on product changes that would include the fix being released. As I would like to add an update to my blog post when a fixed version is released to note t...
by scorpia
Wed Jul 10, 2019 8:08 pm
Forum: General discussion
Topic: Charger compatibility with the Pi 4 (Single Type C CC resistor on Pi4)
Replies: 28
Views: 5208

Re: Charger compatibility with the Pi 4 (Single Type C CC resistor on Pi4)

All spec compliant cables must be able to handle at least 3A (This is because there is no way to identify a non e-marked cable's current rating and 3A is available without power delivery). You might be thinking of the A-C cables and microB adaptors which need to have resistors indicating the current...
by scorpia
Wed Jul 10, 2019 7:02 pm
Forum: General discussion
Topic: Charger compatibility with the Pi 4 (Single Type C CC resistor on Pi4)
Replies: 28
Views: 5208

Re: Charger compatibility with the Pi 4 (Single Type C CC resistor on Pi4)

e-marked cables stand for electronicaly-marked. These cables have a chip in them that can be used to query the cables capabilities over usb power delivery. A major feature that the cables advertise is their current capacity, All USB-C cables can do 3A and via the e-marking cables can state that they...
by scorpia
Mon Jul 08, 2019 5:11 pm
Forum: General discussion
Topic: Charger compatibility with the Pi 4 (Single Type C CC resistor on Pi4)
Replies: 28
Views: 5208

Re: Charger compatibility with the Pi 4 (Single Type C CC resistor on Pi4)

The official adaptor does indeed have the 56k resistors, this means it advertises default USB current (this includes the ability to use previous charger detection such as the battery charging spec) electrically there is nothing enforcing this on the connector side. The type C resistor is connected t...
by scorpia
Sat Jul 06, 2019 9:34 am
Forum: General discussion
Topic: USB Type C of Pi 4 model B
Replies: 25
Views: 1724

Re: USB Type C of Pi 4 model B

While the SOC has dual role support (OTG) support the connector circuitry on the pi doesn't have the required circuitry for doing host mode (DFP) negotiation on the type C port and is wired up for client mode only. Curious where you got this information, because I've heard differently. It is based ...
by scorpia
Fri Jul 05, 2019 9:04 pm
Forum: General discussion
Topic: USB Type C of Pi 4 model B
Replies: 25
Views: 1724

Re: USB Type C of Pi 4 model B

The USB-C port on the Pi4 is in a USB 2.0 client configuration hence many of the connections aren't used. All of the type C connectors should be incompatible as long as the connector you are using has the pins you need for your application (for example the pi uses one without the superspeed pins as...
by scorpia
Fri Jul 05, 2019 12:33 am
Forum: General discussion
Topic: Power Supply - Type C of Pi 4 model B
Replies: 32
Views: 1918

Re: Power Supply - Type C of Pi 4 model B

The connector you have there looks like it is compatible with the pi as it is a full featured type C plug. However given your question I think that this is probably not the connector you need, this connector is designed to be mounted on a paddle board style pcb as part of a cable assembly or directl...
by scorpia
Fri Jul 05, 2019 12:25 am
Forum: General discussion
Topic: USB Type C of Pi 4 model B
Replies: 25
Views: 1724

Re: USB Type C of Pi 4 model B

The USB-C port on the Pi4 is in a USB 2.0 client configuration hence many of the connections aren't used. All of the type C connectors should be incompatible as long as the connector you are using has the pins you need for your application (for example the pi uses one without the superspeed pins as ...
by scorpia
Thu Jul 04, 2019 7:12 pm
Forum: General discussion
Topic: Charger compatibility with the Pi 4 (Single Type C CC resistor on Pi4)
Replies: 28
Views: 5208

Re: Charger compatibility with the Pi 4 (Single Type C CC resistor on Pi4)

My pi has now arrived so I have been able to do some tests. My blog post above has been updated with the info as well. I have checked and both the CC lines are wired up as in the schematic with only one CC resistor rather than two. I then checked several power supplies with and without e-marked cabl...
by scorpia
Mon Jul 01, 2019 6:56 pm
Forum: General discussion
Topic: rpi 4 usb c specs
Replies: 9
Views: 681

Re: rpi 4 usb c specs

The USB C port port as well as providing power has USB 2.0 client features (UFP) only allowing it to be used with Linux USB gadgets (no circuitry for host capability is on the board). There is a sense line going to the IC so it looks to be able to sense the available "Type-C current" from the power ...
by scorpia
Fri Jun 28, 2019 12:18 am
Forum: Beginners
Topic: RPI4 USB C Power Delivery negotiation
Replies: 22
Views: 6159

Re: RPI4 USB C Power Delivery negotiation

I would expect that any vendor restrictions on Type-C charger capabilities would be at the power delivery stage (which the Pi doesn't look to do) as there isn't much scope for communication between charger and device before that. I suspect the issue is a result of the pi only having a single cc pull...
by scorpia
Fri Jun 28, 2019 12:14 am
Forum: General discussion
Topic: Macbook USB C power adapter for RPi 4
Replies: 7
Views: 2410

Re: Macbook USB C power adapter for RPi 4

I suspect this might be a result of the pi only having a single cc pulldown resistor (there should be two) on the USB connector on the pi. I have stared a discussion on this here https://www.raspberrypi.org/forums/viewtopic.php?f=63&t=243875 were there is also a technical write-up for those interest...
by scorpia
Fri Jun 28, 2019 12:12 am
Forum: General discussion
Topic: Charger compatibility with the Pi 4 (Single Type C CC resistor on Pi4)
Replies: 28
Views: 5208

Re: Single Type C CC resistor on Pi4?

Looking around the forum it appears as though this might be the cause of the issues with the pi not powering up with macbook chargers and other laptop supplies. I have written up some details into a more through post https://www.scorpia.co.uk/2019/06/28/pi4-not-working-with-some-chargers-or-why-you-...
by scorpia
Thu Jun 27, 2019 6:38 pm
Forum: General discussion
Topic: Charger compatibility with the Pi 4 (Single Type C CC resistor on Pi4)
Replies: 28
Views: 5208

Charger compatibility with the Pi 4 (Single Type C CC resistor on Pi4)

I was looking at the USB C connector on the PI4 to work out what I could do with it when it arrives in the process of doing so I noticed there is only a singe cc resistor (rather than a resistor per cc channel) on the schematics. Anyone know if this is the case on the actual hardware? If it is it co...
by scorpia
Mon Oct 08, 2018 11:17 am
Forum: Camera board
Topic: bare camera modules for use with compute module
Replies: 2
Views: 565

bare camera modules for use with compute module

Has anyone found a bare IMX219 camera module (like the one used on the camera module) that will work with the pi compute module. While I am aware that the standard pi needs the crypto ID chip I believe the compute module doesn't have this restriction so am looking to put the camera directly on the P...

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