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TLC5947 with Odroid XU4 Issues
Moderators: adafruit_support_bill, adafruit

Please be positive and constructive with your questions and comments.

TLC5947 with Odroid XU4 Issues

by daheist on Wed Aug 12, 2020 3:01 pm

Hello everyone,

I hope to get some help here as I'm stuck and do not find any useful documentation to get support from.

The setup:
Odroid XU4
Armbian on MicroSD
Adafruit Blinka -> Blinka test .py file works fine

I then tested this code:
import board
import busio
import digitalio
import adafruit_tlc5947
spi = busio.SPI(clock=board.SCLK, MOSI=board.MOSI) (had to add the "L" here as otherwise I had an error, really awkward that this is not documented anywhere ?)
latch = digitalio.DigitalInOut(board.D5) (I used almost anything possible here, using this page: https://wiki.odroid.com/odroid-xu4/appl ... e/gpio/spi
I just saw now that I should have used D13, as my pin was connected on GPIO#21, but why shouldn't it be D21 ? Doesn't make sense too, couldn't find proper documentation, i might be blind though.
tlc5947 = adafruit_tlc5947.TLC5947(spi, latch)
tlc5947[0]=0

I still get voltage at pin 0, and my vibration motor (I use phone-like vibration motors) still vibrates. which makes sense as it still receives 5.13V (using a multimeter).

Does any one of you see something obvious here ? I'll try again tomorrow using the proper D pin, although I'm not sure if I haven't already tested this one. I fear cabling, or worse, soldering issues.

Thank you !
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daheist
 
Posts: 8
Joined: Wed Aug 12, 2020 2:48 pm

Re: TLC5947 with Odroid XU4 Issues

by daheist on Sun Aug 16, 2020 5:45 pm

Hi Guys,

May someone from the support team please answer if possible ? I'm really stuck, and can't wrap my head around this.
I tried everything:
Tried using different GPIO pins, for each of them tried all the "names" they could have..
It seems it doesn't matter what I try, I always get 5V output on the TLC pins.

How can I solve this ? What to measure ? Is it possible that the TLC chip is broken ?

daheist
 
Posts: 8
Joined: Wed Aug 12, 2020 2:48 pm

Re: TLC5947 with Odroid XU4 Issues

by adafruit_support_bill on Mon Aug 17, 2020 5:47 am

I always get 5V output on the TLC pins.

Which pins? Your photos do not show anything connected to the outputs of the board. The pins in the V+ row are the power rail and will always have 5v on them if you supply 5v to the V+ pin.

The adjacent row of pins are the PWM pins and will pulse LOW.

adafruit_support_bill
 
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Re: TLC5947 with Odroid XU4 Issues

by daheist on Mon Aug 17, 2020 2:08 pm

Thank you for your answer.

You're right, I wasn't clear enough.

When I measure with a multimeter between the signal and V+ I get 5V, which I guess means that I get no pulse at all.

Hope that clarifies.

daheist
 
Posts: 8
Joined: Wed Aug 12, 2020 2:48 pm

Re: TLC5947 with Odroid XU4 Issues

by adafruit_support_bill on Mon Aug 17, 2020 2:48 pm

The outputs of these are open-drain and as mentioned above the pulse will be active LOW. So if you are seeing 5v between the signal pin and the V+, you must be getting a high-duty-cycle pulse.

What do you see on the other signal pins?

Another possible issue is that these are not designed for running inductive loads like a motor. Driving a motor without a kickback protection diode could result in damage to the board.
https://learn.adafruit.com/transistors- ... -2998941-9

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Re: TLC5947 with Odroid XU4 Issues

by daheist on Wed Aug 19, 2020 3:02 am

Hi,

Thanks for your answer,

So all pins have the same measure, so 5V between pin and its 5V.
I fear I may have damaged the chip then, is there any way I can verify that ?

Thank you !

daheist
 
Posts: 8
Joined: Wed Aug 12, 2020 2:48 pm

Re: TLC5947 with Odroid XU4 Issues

by adafruit_support_bill on Wed Aug 19, 2020 6:51 am

If there was damage from inductive kickback, I'd expect it to be confined to just the one pin. What do you see on the signal pins if you connect the /OE pin to 5v?

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Re: TLC5947 with Odroid XU4 Issues

by daheist on Wed Aug 19, 2020 7:29 am

Just to be sure I test the right thing and don't burn anything in the process

You suggest I connect my Odroid's 5V to the TLC's OE pin ? And then measure between the Channel's V+ and its signal right ?

Thank you !

daheist
 
Posts: 8
Joined: Wed Aug 12, 2020 2:48 pm

Re: TLC5947 with Odroid XU4 Issues

by adafruit_support_bill on Wed Aug 19, 2020 7:50 am

Correct. Pulling /OE to 5v should disable the outputs on the signal pins.

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Re: TLC5947 with Odroid XU4 Issues

by daheist on Sat Aug 22, 2020 6:17 pm

Well I just tested,

I must be doing something wrong I guess, so..

-> I use my initial setup, and then instead of having my 5V from Odroid go to V+ from board I put it towards /OE as you said.
I feel like pulling it to /OE or to nothing would do the same ?
Results show -2V on every pin (so V+ is 0 and signal is at 2V)

FYI, without OE pin plugged, signal seems to be at around 3V and V+ still 0 obviously.)

Does that give us some indications ?

Thanks again for the feedback !

daheist
 
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Re: TLC5947 with Odroid XU4 Issues

by adafruit_support_bill on Sun Aug 23, 2020 5:51 am

Results show -2V on every pin (so V+ is 0 and signal is at 2V)

You need to power the board when you do that. V+ should be a 5v.

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Re: TLC5947 with Odroid XU4 Issues

by daheist on Sun Aug 23, 2020 6:51 pm

Oww,

So I need to pull the 5V from my odroid to both V+ and /OE ?

Sorry, I'll try again tonight.

daheist
 
Posts: 8
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Re: TLC5947 with Odroid XU4 Issues

by daheist on Thu Aug 27, 2020 4:50 pm

Can you confirm ?

So I need to pull the 5V from my odroid to both V+ and /OE ?


Again, I don't wanna burn my brand new board :/

daheist
 
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Re: TLC5947 with Odroid XU4 Issues

by adafruit_support_bill on Thu Aug 27, 2020 7:38 pm

So I need to pull the 5V from my odroid to both V+ and /OE ?

Yes. You cannot disable the outputs if the board is not even powered up.

Again, I don't wanna burn my brand new board :/

It may be too late. You should never apply voltage to an input pin for a board that is not powered. Most chips do not tolerate input voltages that exceed the supply voltage (VCC) and the TLC5947 is no exception. See section 6 of the datasheet:

https://www.ti.com/lit/ds/symlink/tlc5947.pdf

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Please be positive and constructive with your questions and comments.