Logic Level converter help

I switched over to using and Arduino Due from an UNO and now have to change the voltage requirements so I can send my inputs to my stepper drivers which are +5V.

I was looking at this (TXS0108E 8 Way Level Conversion Module) and it seems straight forward with the A pins at 3.3V switching to +5V on the B pins, I supply a +5V and 3.3V power to each side of the chip. The thing that is holding me up is the OE pin and what needs to go there, I have seen some wiring it to 5V and some going to GND with it but none of them are driving stepper drivers. There are also requirements for a pull down resistor thrown in there to really confuse me so hopefully I can get someone to point me in the right direction.

spec sheet for converter is here.
https://www.mouser.com/ds/2/405/txs0108e-450506.pdf

here is how I think it should go,
DUE -> txs0108 -> driver
3.3v -> VCCA
5v -> VCCB
GND -> GND
GND -> OE ???(or leave open)
Pin 3 -> A1 -> B1 -> Driver
Pin 4 -> A2 -> B2 -> Driver

But this leaves out the resistors and I've seen some diagrams on google that show capacitors on the power supply lines.

ribbonman:
I switched over to using and Arduino Due from an UNO and now have to change the voltage requirements so I can send my inputs to my stepper drivers which are +5V.

Your previous posts mention a ST-M5045, with current (opto) inputs.
Why do you think you need 5volt for that. The writing on the module?
Did you try it with 3.3volt.
Leo..

Wawa:
Your previous posts mention a ST-M5045, with current (opto) inputs.
Why do you think you need 5volt for that. The writing on the module?
Did you try it with 3.3volt.

I seem to recall another Thread which questioned whether a Due can provide enough current for the opto inputs.

...R

The problem is the low current ratings of the Due pins, not typically enough for standard opto-isolators,
although its worth measuring what they take, and check that the device is reliable at 3.3V anyway

Wawa:
Your previous posts mention a ST-M5045, with current (opto) inputs.
Why do you think you need 5volt for that. The writing on the module?
Did you try it with 3.3volt.
Leo..

The spec sheet for the driver indicates it is +5V input, I have tried it but it doesn't operate it. I also have 2 other drivers of cheaper quality than the ST-M5045 that also take a +5V signal.

Robin2:
I seem to recall another Thread which questioned whether a Due can provide enough current for the opto inputs.

...R

I had read that post also, which is why I'm looking at this converter.

MarkT:
The problem is the low current ratings of the Due pins, not typically enough for standard opto-isolators,
although its worth measuring what they take, and check that the device is reliable at 3.3V anyway

I tried running with 3.3V and the motor doesn't move.

I read the spec sheet of the converter a few times last night and really only had 2 questions about hooking it up and they were,

  1. The specs state to use an appropriate sized resistor to pull OE to ground to make all output pins go High. Do I want the output pins HIGH on power up, I would want the input pins(Ax) to tell the output(Bx) pins to go LOW or HIGH wouldn't I?

2)What is the function of the .1uF capacitors that the spec sheet shows on both power supply lines?

I gave this a shot last night but it wouldn’t move the motor, I connected it this way

Due TXS0108 Driver

3.3v Va
5v Vb

GND GND GND(all GND’s tied together back to board GND)
GND w/10K R OE(tried with and without)

pin3 A1 - B1 step+
pin4 A2 - B2 Dir+

any idea’s where to go from here?

Well I read a post on another thread and decided to give it a try,

[here

Crossroads said try one of the voltages on the OE pin to get the correct voltage and it did work, one side is at 3.3v and the high side is at 5v but when hook up the stepper driver to it and set the pin HIGH the voltage drops to 1.1v, can the opto-isolated inputs drain that much voltage?

Anyone have any thoughts?

](http://forum.arduino.cc/index.php?topic=406261.0)

Got a link to the stepper driver?
I would use a chip like 74ACT125 with 24mA drive current to convert 3.3V signals to 5V signals.

CrossRoads:
Got a link to the stepper driver?
I would use a chip like 74ACT125 with 24mA drive current to convert 3.3V signals to 5V signals.

I tried it with ST-M5045 and also a DIV268N-5A but no luck.

here's the ST-M5045

DIV268N

From the TSX0108 Datasheet :

8.3.4 Enable and Disable

The TXS0108E has an OE pin input that is used to disable the device by setting the OE pin low, which places all I/Os in the Hi-Z state. The disable time (tdis) indicates the delay between the time when the OE pin goes low and when the outputs actually get disabled (Hi-Z). The enable time (ten) indicates the amount of time the design must allow for the one-shot circuitry to become operational after the OE pin goes high

You need to connect the OE pin to VCCA (the 3.3V supply), and not GND for the Output to be Enabled.

JohnLincoln:
From the TSX0108 Datasheet :
You need to connect the OE pin to VCCA (the 3.3V supply), and not GND for the Output to be Enabled.

Hi @JohnLincoln,

I didn’t quite understand what the spec sheet was trying to tell me, I have tied the OE pin to 3.3v but the output side would only go to 3.3v instead of 5v like I need,so I connected the OE to the 5v and I then got 5v on the output side.

CrossRoads:
Got a link to the stepper driver?
I would use a chip like 74ACT125 with 24mA drive current to convert 3.3V signals to 5V signals.

ST-M5045 driver uses +5V with a input current rating of 7 - 16mA

I still haven't got it to work, when I apply +5V to OE i get +5V on the output side of the chip but when the driver is connected the voltage drops to about +2.5V.

I'm just starting with electrical specs and would love someone to explain in laymen terms why it is dropping.

It is impossible to determine what you are currently doing.

ST-M5045? TSX0108? 74ACT125? Other?

A schematic is needed at this point with part numbers/device types. Hand drawn is fine.

Specs for logic converter are on the first post and the specs for drivers are on post #8 and here is a wiring diagram.

That driver module has optos between the inputs and the matching signal positives.

You must connect 5volt of the Arduino/converter to all the signal positives in use.

You can leave ground of the driver connected, but ground has no function here.

Leo..

Wawa:
That driver module has optos between the inputs and the matching signal positives.

You must connect 5volt of the Arduino/converter to all the signal positives in use.

You can leave ground of the driver connected, but ground has no function here.

http://s3.amazonaws.com/s3.image.smart/download/101-80-109/2-Phase_stepper_Motor_Driver_ST-M5045.pdf
Leo..

I read it has optos on the inputs but I'm trying to learn why the voltage drops when I connect the converter to the driver. The voltage on the B side of the Logic converter is at 5V until I connect the Driver and then it gets cut in half and doesn't send an input to the Driver that it can read(below minimum threshold). Is that a causal effect from the optos?

The 5V from the arduino goes to the logic converter 5V pin which distributes the 5V to the 5V side of the converter(3.3V pin is Va and 5V is Vb on converter).I have supplied both 3.3V and 5V to the converter.

The txs0108 is on a small board like this,(as usual no spec sheet on the board, just the chip)I used the adafruit site which had a similar board but slightly different chip for the wiring.

Maybe time we see a real picture of the setup.
Leo..

I spoke with a guy at EZSBC who looked at the TXS chip and said it wouldn't drive the stepper driver because it didn't have a driver to pull the signal high or low, so I purchased a level shifter from his company and it works great. Here is a link to the converter I bought.

LS2 logic level converter