Connect accelerometre throught USB to zybo

[plazma33]

hello ,

I have a linux ubuntu  on my zybo board and I m going to use an accelerometre , So can I connect it throught UART USB instead of Gpio port  ?

please help

[D@n]

@plazma33,

I'm not sure I understand what you wish to do.  What accelerometer do you have?  Does it even have a USB capability?

The USB UART capability of the Zybo is, from the standpoint of the Zybo, a serial port.  From a USB standpoint, it is a peripheral USB port.  You can plug it into a USB host port (such as your PC), and communicate via USB (on your PC) and a serial port (on the Zybo).  It's not something that you can connect a more generic peripheral into, though.  That would be the USB on the go (OTG) port, but only if the part you want to plug into the Zybo is a USB peripheral.

Dan

[plazma33]

@D@n

thank you for the information , I m trying to connect a "Pmod ACL: 3-axis Accelerometer" to my zybo board throught a USB port (UART or OGT) , so I m looking for a solution , I found something that might help me wich is the "Pmod USBUART: USB to UART Interface" so i can plug the Accelerometre to the USBUART and then plug the USBUART into the ZYBO throught a USB port , can you guide me ?? , if  what I m talking about is a solution  , then is it the only one ? because I have to perchase the USBUART and that will take time.

here is both the USBUART and the ACCELEROMETER . 

http://store.digilentinc.com/pmod-usbuart-usb-to-uart-interface/

http://store.digilentinc.com/pmod-acl-3-axis-accelerometer/

[D@n]

@plazma33,

Ok, thanks for posting the pictures.  That helps.  I'm not sure why you think you need the PMod USBUART, though.

It might make more sense to

1. Connect the Zybo to your PC via the USB UART (No PMod required--it's built into the Zybo),
2. Connect the accelerometer to one of the Zybo PMod ports,
3. Read the accelerometer using the Zynq chip on the Zybo,, and
4. Report the data back through the USB UART (still built into the Zybo) to the PC host.

Does this make any more sense to you?

Dan

[plazma33]

@D@n

thank you ,, yeah all your messages are clear , I know that I can connect the Accelerometre directly to the PMOD connector on the zybo and then to the PC ,

BUT here is what I m doing so you'r going  understand why I need the USBUART 

        -  I booted linux on the zybo so I should not use the PC even if I can ,

        - I tried to connect the ACCELEROMETRE to the zybo throught the PMOD connectors  , but it's not detected by the zybo , 

        - after searching a lot and making lots of hardware diagnostics i found out that the PMOD connectors on the zybo are broken (several pins are broken)

        - i found out that the USB OGT is working and the zybo can read date throught it , ( I teste  : keyboard , mouse , bleutooth dongl , wifi dongle...)

        -I decided to read data from the ACCELEROMETRE throught the USB port on the zybo ( which is the OGT as you told me) 

So I think that my problem is cleare  now  ! 

I will be soo greatful if you find a solution for me

[D@n]

@plazma33,

I think I can safely say on Digilent's behalf that there are no officially supported solutions that involve wiring the accelerometer outputs to the PModUSBUART.  Indeed, doing so sounds like you are trying to fit a square peg (either I2C or SPI) into a round hole (UART).

Wouldn't it make more sense to find the Pmod problems and try to fix them?  Soldering iron on the edges of the board perhaps?

If not, did you actually have any ideas about how you wished to plug a non-UART device into a UART interface?

Dan

[plazma33]

@D@n

thank you for your fast reply , I tried to fix the Pmod problems but I failed it's a bit difficult , It's true that it looks like trying to fit a Square peg in a round hole , 

but I did not meant that that USBUART is the solution , I m just trying to know if there is a sort of a convertor interface from Accelerometre output to the UART port or the OGT port, 

is there any converters ?

[D@n]

@plazma33,

You could program any of the Digilent FPGA boards, and possibly even the CPLD board, to be a converter.  I'm sure you could also program a chipKit for that purpose as well.  My first suggestion for you (just because I like FPGAs) would be either CMod A7--since it has a simple UART interface over USB, as well as quite a few programmable pins.  However, if all you need is an interface converter, you might find the cheapest FPGA pricey for that task.

A cheaper option might be to use a smaller, cheaper, microcontroller (also an ARM, like what's within the Zynq) ... but despite drooling over such, I've never bought one to know how easy or hard it is to build a design for it.  (It helps to not work for Digilent ... I can promote competitors products, no?   )

Dan

[plazma33]

@D@n

really ,, you where soo helpful , it's beyond working with a company , you did more then should ,  thank you for your help , you saved for me more than you imagine ,

and No it's not about promoting , you'r finding solutions so the Zybo and other digilent products become easier  to manipulate .

THANK YOU

[D@n]

@plazma33,

Just remember, I've never used a Teensy before even though I've always wanted to try one.  As a result, I cannot promise you that what I've just recommended to you will work.  Still, they have their own forums page, so you should be able to get some answers there.

Dan

[plazma33]

@D@n

Thank you but I prefer  CMod A7 , it's more guaranty and sure  

Firas

[D@n]

@plazma33,

Well now ... that's a decision after my own heart, too!  Yes, I would also prefer the CMod A7, if I had the budget for it--and $75 isn't all that bad.

I'd offer to develop your solution for the CMod-A7 along with you ... but the closest thing I have on my desk is the ACL2.  (Since I don't work for Digilent, I don't get all their toys on my desk.  Still ... I do have an impressive number, and they have been generous ...)  I just don't have the ACL3.

One of the questions I was struggling with has always been .,.. could an accelerometer (plus appropriate software) be used to determine where a robot is on an FTC field?  Perhaps one of these days I'll actually get to play with such an idea.    (It's what I got the ACL2 for ...)

Dan

[plazma33]

thank your for your offer it very nice from your part ,

and yeah , your number reflects your generosity toword peoples , but bout the accelerometre I dont think that it can not determine an object position and here is my explenaition ( based on my mathematics and physics background)  acceleration is not the only variable that throught it we can for example determinate how much a robot made  x meters in  one of the thre axes (x,y,z) , the other variables that are missing are :

                                                                            - the periode of time T spent by that robot with that acceleration A

                                                                            - the mass of that robot 

                                                                            - the wheels type ==> so we get the h constant 

                                                                            - the type of the floor ==> so we get the friction variable to calculate 

this is why I think using an accelerometre is quite difficult if you want to be presize with the results ,  

For me I m using an accelerometre to count hou much a boxer punch on a punching bag is in Newtons , so if I know the wheight of the bag and the acceleration and the surface of contact I can know how much Newtons he putted into that punch .

here is a video link for a small prototype of what we are going to do   , it's going to be way better than it looks in the future  :

https://www.youtube.com/watch?v=5SkvQ-FXG3s&t=3s

Firas

                                                                             

[plazma33]

hello

I bought a new ZYBO board so no need to look for difficult solutions  
Now I have other problems.

-I created a petalinux project and I imported the "hw" description then builded BOOT.BIN

-GOAL : booting linux on ZYBO and recognizing all the GPIOS where I will plug (GYRO, Accelerometre,Bleutooth,Leds,Buttons)

-assuming that the Devitree is well configured and contains all of the GPIOS , the Petalinux RG Manual contains lots of options but
I dont see at any of the steps that I should put the Devicetree alongside with BOOT.BIN and linux image in the FAT32 partition see image(1) below)
RG manual link : https://www.xilinx.com/support/documentation/sw_manuals/petalinux2015_4/ug1144-petalinux-tools-reference-guide.pdf

-I'm following this type of SD card structure (see image(2) below) and I think this is the good way 

-PS : -I already configured the SD card in two partiton (FAT32 and ext4) 
     -the ext4 partition contains a linario filesystem
     -I configured the RootFS type as "SD" in the petalinux project

what should I do  ??
THANK YOU FOR YOUR HELP. 
     

[sbobrowicz]

Here was the message that seemed to help out that I provided over a private message:

Typically, the image.ub file contains the device tree, ramdisk, and kernel. When wanting to boot into the ramdisk file system (instead of linaro), you only need to copy boot.bin and image.ub to the first partition of your SD. This of course means you will need to build everything you want in your file system using petalinux, which can be a chore if you are planning on using a lot of third party libraries and programs. 

So if you want to boot into Linaro, you should follow the section titled: "Configuring SD Card ext filesystem Boot" in the petalinux RG (pg 61). Be careful to skip step 9 of the section titled "PetaLinux Configuration and Build System Image" and step 3 of "Copying Image Files". This is because those steps will replace your linaro file system with one created by petalinux. If you skip them, then the kernel will just boot whatever file system is present on the second partition, in your case, Linaro.

 When you follow those steps, image.ub only contains the kernel and device tree, not the ramdisk. This should work for your purposes.

[sbobrowicz]

Please don't post any more in this thread since the accelerometer question over USB uart has been answered.