quinzyamg
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Joined: Wed May 22, 2019 7:16 am

Arduino connection to the PI (with 12C)

Wed May 22, 2019 7:20 am

Is there a way to connect an Arduino to the pi besides the usb connection. I know you can connect it using the TDX and the RDX pins but the issue is that my gsm add-in already use these pins, can i connect the arduino to different GPIO ports to still get the same data transfer capabilities or is there just no way apart from using either the above mentioned pins or a USB cable.


quinzyamg
Posts: 5
Joined: Wed May 22, 2019 7:16 am

Re: Arduino connection to the PI

Wed May 22, 2019 10:28 am

Thank you dude, you're a life saver!

quinzyamg
Posts: 5
Joined: Wed May 22, 2019 7:16 am

Re: Arduino connection to the PI (with 12C)

Fri May 24, 2019 8:56 am

I know my question was answered in the above part of the post, but i seem to have run into a new problem, my data transfer rate is very intermittent. At first i thought it was due to me not having a logic level shifter connected, but for some reason with the shifter connected i get no i2c detection from the pi's side. What could be the problem.

Brandon92
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Location: Netherlands

Re: Arduino connection to the PI (with 12C)

Fri May 24, 2019 9:07 am

Did you connect the level shifter in the right direction? A picture could help also.

quinzyamg
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Joined: Wed May 22, 2019 7:16 am

Re: Arduino connection to the PI (with 12C)

Fri May 24, 2019 9:13 am

I think so. the picture attached is the exact same Shifter i used. I put the HV on the Arduino's side and the LV on the pi's side. i Also measured the voltages on both sides and on the Pi it reads 3.3V and on the Arduino it's 4.8V.

Also a link to where i bough it:
https://www.robotics.org.za/BOB-12009
Attachments
20190524_105256(2).jpg
20190524_105256(2).jpg (54.91 KiB) Viewed 2161 times
BOB-12009-000-650x350.jpg
BOB-12009-000-650x350.jpg (43.94 KiB) Viewed 2164 times

Brandon92
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Location: Netherlands

Re: Arduino connection to the PI (with 12C)

Fri May 24, 2019 9:29 am

You have forgotten to connect the 3,3v and 5v to the level converter. Like the schematic in the link you posted.

quinzyamg
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Joined: Wed May 22, 2019 7:16 am

Re: Arduino connection to the PI (with 12C)

Fri May 24, 2019 9:34 am

I left the 3.3v and 5v off, since i still power the arduino via the usb. Is it still necessary to connect the power for both even if both are separately powered?

Brandon92
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Location: Netherlands

Re: Arduino connection to the PI (with 12C)

Fri May 24, 2019 9:43 am

Both voltages need to go to the level shifter, otherwise the level shifter will not work.

Edit:
The voltages are used to provide power to the level shifter itself. Without that connected it will not work properly. I could give you a detailed explanation why.

alphanumeric
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Location: Sydney, Nova Scotia, Canada

Re: Arduino connection to the PI (with 12C)

Mon May 27, 2019 12:21 pm

What he said, I have this one, https://www.adafruit.com/product/757 It won't work unless you power the 5V and 3.3V inputs.
If your wanting high speed you may be better off with something like this, https://www.adafruit.com/product/395

alphanumeric
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Re: Arduino connection to the PI (with 12C)

Mon May 27, 2019 12:22 pm

What Arduino do you have? I ask because some use 5V logic and some use 3V logic. You may not even need the level shifter?

gordon77
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Re: Arduino connection to the PI (with 12C)

Mon May 27, 2019 6:42 pm

alphanumeric wrote:
Mon May 27, 2019 12:22 pm
What Arduino do you have? I ask because some use 5V logic and some use 3V logic. You may not even need the level shifter?
The OP said...
i Also measured the voltages on both sides and on the Pi it reads 3.3V and on the Arduino it's 4.8V.

alphanumeric
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Location: Sydney, Nova Scotia, Canada

Re: Arduino connection to the PI (with 12C)

Mon May 27, 2019 7:23 pm

gordon77 wrote:
Mon May 27, 2019 6:42 pm
alphanumeric wrote:
Mon May 27, 2019 12:22 pm
What Arduino do you have? I ask because some use 5V logic and some use 3V logic. You may not even need the level shifter?
The OP said...
i Also measured the voltages on both sides and on the Pi it reads 3.3V and on the Arduino it's 4.8V.
I saw that, just not 100% sure where they measured it? If it was on the level shifter it may be because its shifting it to 5V?
Can't hurt to know what Arduino they are using.

mindsacred
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Joined: Tue Mar 19, 2019 6:01 am

Re: Arduino connection to the PI (with 12C)

Sat Jun 15, 2019 6:18 am

Brandon92 wrote:
Fri May 24, 2019 9:43 am
Both voltages need to go to the level shifter, otherwise the level shifter will not work.

Edit:
The voltages are used to provide power to the level shifter itself. Without that connected it will not work properly. I could give you a detailed explanation why.
Hi!

Can you explain me pls?

Brandon92
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Location: Netherlands

Re: Arduino connection to the PI (with 12C)

Sun Jun 16, 2019 6:15 pm

mindsacred wrote:
Sat Jun 15, 2019 6:18 am
Brandon92 wrote:
Fri May 24, 2019 9:43 am
Both voltages need to go to the level shifter, otherwise the level shifter will not work.

Edit:
The voltages are used to provide power to the level shifter itself. Without that connected it will not work properly. I could give you a detailed explanation why.
Hi!

Can you explain me pls?
What do you want to be explained precisely?

gordon77
Posts: 3918
Joined: Sun Aug 05, 2012 3:12 pm

Re: Arduino connection to the PI (with 12C)

Sun Jun 16, 2019 6:46 pm

mindsacred wrote:
Sat Jun 15, 2019 6:18 am
Brandon92 wrote:
Fri May 24, 2019 9:43 am
Both voltages need to go to the level shifter, otherwise the level shifter will not work.

Edit:
The voltages are used to provide power to the level shifter itself. Without that connected it will not work properly. I could give you a detailed explanation why.
Hi!

Can you explain me pls?
Take a look here. https://wiki.analog.com/university/cour ... el-shifter

You will see in the diagrams you need Vddi and Vddo.

alphanumeric
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Location: Sydney, Nova Scotia, Canada

Re: Arduino connection to the PI (with 12C)

Sun Jun 16, 2019 7:16 pm

Going by the Blue one in the picture above
+5V from the Arduino needs to go to the HV terminal on the High Logic level side
and the 3.3V from the Pi needs to be connected to the LV terminal on low logic level side.

EDIT: Ops got it backwards fixed now sorry. :oops:
Last edited by alphanumeric on Sun Jun 16, 2019 9:59 pm, edited 1 time in total.

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davidcoton
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Re: Arduino connection to the PI (with 12C)

Sun Jun 16, 2019 9:54 pm

alphanumeric wrote:
Sun Jun 16, 2019 7:16 pm
Going by the Blue one in the picture above
+5V from the Pi needs to go to the HV terminal on the High Logic level side
and the 3.3V from the Arduino needs to be connected to the LV terminal on low logic level side.
That doesn't sound right, although it would work if the Arduino has a 3V3 supply.
Pi is LV side (3V3), Arduino is HV side (5V0). So 3V3 from Pi to LV, 5V from Arduino to HV.
Or have I missed something?
Signature retired

alphanumeric
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Joined: Tue Jan 19, 2016 2:17 pm
Location: Sydney, Nova Scotia, Canada

Re: Arduino connection to the PI (with 12C)

Sun Jun 16, 2019 10:01 pm

davidcoton wrote:
Sun Jun 16, 2019 9:54 pm
alphanumeric wrote:
Sun Jun 16, 2019 7:16 pm
Going by the Blue one in the picture above
+5V from the Pi needs to go to the HV terminal on the High Logic level side
and the 3.3V from the Arduino needs to be connected to the LV terminal on low logic level side.
That doesn't sound right, although it would work if the Arduino has a 3V3 supply.
Pi is LV side (3V3), Arduino is HV side (5V0). So 3V3 from Pi to LV, 5V from Arduino to HV.
Or have I missed something?
You didn't miss anything, I botched it and had them reversed. Edited and fixed now. :oops:

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