The Teensy 3.5 is expecting an input when I connect a wire to the Vin pin and disables power from the usb. The current wiring schematic in the manual and explained above does not work with this Teensy logic. I'm slightly confused on why this has not happened to anyone else on this forum. Did I miss a step that disables the Teensy 3.5 Vin pin logic?

Thanks, Chris. I just want to list the specific statements that I sent to you in an email and you confirmed, along with a hand drawn schematic (see below). This may break it down even more so.

1. Both microprocessors (Teensy and Mega) are being powered by the +5V from their respective USB ports. This is labelled +5V/GND.

2. The Teensy +5V powers the GX16-2, which powers all the robot’s encoders and limit switches. The GX16-2 actually connects to the Teensy's Vin pin, but in the Teensy schematic, internally, Vin is connected to the USB's 5V. Additionally, the Teensy's +3.3V output powers the stepper motor drivers’ PUL+ and DIR+ inputs.

3. The Mega’s USB port also provides +5V/GND, but it just powers the Mega board.

4. The 5V power supply provides separate power, labelled +5V1 and GND1. This gets connected to the DIN rail, and powers the relay board. Since I am using a servo gripper instead of a pneumatic one, I will also run this +5V1/GND1 power to a GX16-4 connector dedicated to the gripper.

5. GND1 also gets connected to the Mega board ground, which internally connects it to the GND ground from the USB port.

One Question: earlier in this post (e.g., D.D., March 18) the question was raised about whether 3.3V was adequate for inputs to the stepper drivers. Given that the Teensy's 3.3V is derived from the USB's 5V input, and this 5V appears at the Vin pin, could we power the stepper driver inputs from Vin instead of the 3.3V pin, and better meet the specs of the drivers?

Thanks, Ray Kimber

Hello all, Im sorry I missed this post. Raymond Kimber brought this to my attention and he may have some additional info to add to this topic. Please note that in the earliest version of the manual I had the teensy, arduino 5v supply and the relay board on a common ground and the 5v supply was also sent to the robot to power the encoders and limit switches.   The overall purpose of the 5v supply is simply to power the relays as the arduino (usb 5v) does not have enough amperage to power the relays.  I found using the 5v supply to power the robot encoders wasn't ideal.  In the current architecture to reduce noise the teensy usb 5v powers the encoders and the limit switches and does not share a ground signal with the 5v supply and the 5v supply is only wired for the relay board. 

Looking at the confusion in the manual, I decided to do a few mods. The 5V PSU will only power the limit switches and the encoders. I then decided to power the teensy, relay board and the mega from buck converters to get the correct voltage to each which means that they will be permanently powered, but then cut the red wire in the USB cables so they are not powered from the USB. Unfortunately, I have still got to complete the AR3 build, but I have wired it up outside of the control box and it seems to work okay. We will see what happens when it is finally put ino action.

Well, that is relly interesting and meaningfull, D.D. Right now, I have liaised directly with Chris to kind of debug my own build. I'll raise those questions/suggestions of yours with him.

Hi Pierre,

"...and the Teensy should be powered only via the USB connection to your PC."

From my understanding, you have two options to power the Teensy.

1) USB connection to PC.

2) Wired either to the GX16-2 connector (provided the connector is wired to the DIN rail for 5V), or wired directly to the DIN rail for 5V.

Also, I believe you can do both simultaneously and the Teensy will automatically decide which one but don't quote me on that. To me, this makes sense since you might have it powered independently from the USB cable but at some point need to reconnect the USB cable to upload a new program.

Spec's for the 2 boards:

Teensy Vin: 3.6-6 volts (link)

Mega 2560 Vin:

Limits = 6-20 volts

Recommended = 7-12 volts (link)

And this is where I have an issue using the 5V power supply for the Arduino. The Arduino operate at 5V but has a low limit of 6V with 7V being recommended. This is why I'm looking at adding a second power supply for the Arduino.

Other items related to wiring:

I noticed that J4 driver (DM320T) Opto pin is powered via the 3.3V output pin from the Teensy. The datasheet (link) says the typical voltage is +5V but fails to say the minimum or maximum. It's a guess that 3.3V is sufficient.

This same voltage is connected to the PUL/DIR signals for the other drivers (DM542T), however, the datasheet for this driver (link) says 4-5V. Maybe I'm being picky, but a weak signal could cause potential issues. On this issue, I'm tempted to use the 5V power supply for these connections instead of connecting it to the Teensy.

The other change I'll be implementing in my build, is running separate power supply lines for each individual driver, rather than daisy-chaining them as noted in the datasheets.

I don't mean to be nit-picky. I know builds of this nature can have bugs to be worked out and perhaps this information will be beneficial to someone in the future when they run into confusion or issues.

Hi Pierre,

I noticed the same wiring error as you have while I've been reviewing the manual for the AR3, as I prepare for my own build.

I also searched these forums for a possible answer but I did not find one. The following posts remained unanswered:

https://www.anninrobotics.com/forum/robot-builds/ar3-building-wiring-completed

https://www.anninrobotics.com/forum/questions/5v-psu

Here's my understanding:

The pictures from page #238 to #241 shows two pairs each of black and red wires coming from the 4th pair (black) and 5th pair (red) of the DIN rail terminals. This is where the manual is missing the instructions to add this second pair of wires, including the instructions to solder said wires to the GX16-2 plug on the enclosure door even though the pictures show the installed wires.

If you then jump to page #265, this is when you solder another pair of 22awg wires (black and red) to the GX16-2 plug on the enclosure door. The other end of these wires need to be soldered, with heat shrink, to a pair of jumper wires, which are then connected to the Teensy 3.5 appropriate pins as instructed on page #265 (bottom image). This is how the Teensy 3.5 derives it's power. From 5V power supply unit, to the DIN rail, to the GX16-2 plug, to the Teensy 3.5. Please note, that it is my opinion that the red jumper wire mentioned on page #258, is the same red jumper wire that will be soldered and connected to the Teensy 3.5 Vin pin on page #265. We're missing the follow through on that instruction, including the making of the black wire.

As you can tell, there are missing steps in the manual. Perhaps the community will help with the next revision?

So to answer you're question, from what I can tell, yes to either of your methods asked. The power for the Teensy 3.5 is ultimately derived from the 5V connection point on the DIN rail, which as you know, is sourced from the 5V power supply unit. What's the best method regarding common grounding techniques is another question I choose to side-step for now ;)

Hope that helps Pierre so you can continue with your build.

Would you mind sharing whether you're building the aluminum or 3D printed version?

Separate but related to your post, I'm confused by where the missing +V side of power for the Arduino Mega 2560 is coming from. I can only assume the power will then be derived from a direct connection via the USB cable to a PC and the -V side for establishing a common ground. According to the datasheet, "The board can operate on an external supply of 6 to 20 volts. If supplied with less than 7V, however, the 5V pin may supply less than five volts and the board may be unstable."

As instructed in the manual, we're not using 5V from the Arduino for the relay module, however, it's the "board may be unstable" part that leaves me uncomfortable. Are they referring again the stability of the 5V output from the Arduino, or the boards ability to function properly? I'm thinking the latter but I would like to hear other's opinion on the matter.

Regards,

D.D.