Ouch! Love the continous improvement but hate that none of this is communicated until so late. We purchased 53 Super IQ kits and 12 V5 super kit bundles in the past couple of years. Now both are already yesterday’s news. I think VEX could garner some more goodwill if they made announcements about things coming down the pike sooner rather than later.
I’m sure there are many talented engineers working on the V5 system and that a lot of thought and care has been put into designing it, but that doesn’t mean people, and more over companies don’t sometimes make mistakes.
The RS-485 transceivers in the V5 (by far the part most commonly killed by ESD) do contain some ESD protection built in, however, only to a fairly limited capacity. The datasheet for the part in question states at the bottom of page 20 that, “Although the SN65HVD178x family is internally protected against human-body-model ESD strikes up to 16 kV, additional protection against higher-energy transients can be provided at the application level by implementing external protection devices.” It then goes on to show and describe a typical application circuit containing TVS diodes on the data lines to protect against higher levels of ESD discharge. Please correct me if I’m wrong, but I do not see any such protection diodes (or any other external protection) in the V5 or any of the sensors / motors that I’ve examined.
I’ve heard rumblings that VEX didn’t deem it a necessary problem to fix due to the V5’s largest target market supposedly being the classroom; and while I disagree with this reasoning due to the poor experience it gives your competition customers, I’m obviously not a VEX employee so all I can do is accept it. However, with the release of the VEX EXP system, that reasoning makes even less sense as now there’s a separate device targeting classroom use relegating the V5 to, as far as I’m aware, primarily competition use.
I (and I’m sure others) would greatly appreciate a proper response that addresses our concerns with ESD protection on the V5 system other then just the usual, “We have always had ESD protection in Smart Ports.” Thank you for your time and consideration.
Looks like the comparison page has the wrong battery capacity listed.
It has been updated.
Did not expect robot parts to reduce in cost. Thank you to the VEX Engineers for reducing cost and streamlining the platform.
I also like the new EXP product name.
EXP isn’t meant to replace V5, it’s a part of the V5 ecosystem. It’s a lower cost control system so more schools have access to them, as the regular V5 system is pretty expensive if you’re trying to buy many at a time.
Not necessarily “new” products, but VEXpro 2" Mecanum Wheels have just been cross-listed on the V5 website, making them VRC Legal.
Note: These Mecanum Wheels must use V2 VersaHex Adapters (also found on the page) so that they can be used with High Strength Shafts.
Re: “We have always had ESD protection in Smart Ports. The issue has not been ESD protection as much as ESD generation.”
Our teams (mostly our volunteer parents/mentors) spent thousands of dollars on new brains and anti-static tiles. Last season we took every possible precaution and because of the pandemic only competed in LRT/LRS competition on our own field. The best we were able to do is fry ONLY 4 ports on a brand new brain. This came out of nowhere, as we were practicing for skills. It also happened in the middle of a match when our robot lost a drive motor. Symptoms always the same for us. Motor stops responding. First instinct is to panic. Second to blame the programmer. Third to blame anyone who did not tighten a shaft collar and let the shaft come out. Fourth to replace the motor, has to be it right? Then cynicism steps in, panic moves to the side and experience whispers “it is always a dead port on the brain you bozo”. The port is blinking a faint red. We already have a test motor just for that. It is labeled “test motor” so we know it is a good one. Plug it in, it also blinks - we know port on the brain is dead. Move to a different port, rename/reprogram, go back to what you were doing before. A frustrating waste. It is always the TI RS-485 transceiver chip on the brain that burns, not the one inside the motor. For us at least it is. We stopped mentioning it because invariably the answer is the same. Well you did not spray with antistatic. Well your room is too dry, you did not use a humidifier. Well you did not wear your antistatic bracelet, well you did not touch a grounded piece of metal - the field perimeter is not grounded you bozo. Well you are wearing socks - get rid of the socks, well your room has carpet - get rid of the carpet, well do this don’t do that. And now “We have always had ESD protection in Smart Ports”. These devices are supposed to handle the harsh conditions of robot competitions and constantly assuming teams did something wrong because ports on a $250 device burn or brains turn white and stop braining gets depressing and frustrating. Ports do constantly burn and we are not making it up and we are not all complete bozos (only a vast bunch of us). Those RS-485 chips (marked TI VP1782) are actually notorious for being super sensitive to ESD. At least PLEASE put those chips on a socket (surface soldering is not for the average bozo) so we can just get a bag of them (while supplies last, soon we’ll have to get them at 15x the price from scalpers like graphics cards or PS5) and replace them when they burn, just like good old fuses. Also, RS-485 chips more resilient to ESD seem to exist, at least as far as their datasheet goes (link). The TI datasheet specifically mentions the need for TVS diodes. Could be wrong / blind / bozo but can’t see them on these images, there are resistors and condensers, no diodes (link). Apparently without the diodes, the chip should handle 16Kv of ESD. According to Google a human body can produce max 15Kv (bozos walking in socks on carpet dragging their feet). So then how do these burn on antistatic tiles by just driving the robot around and not actually touching it? The more you learn, the more you don’t know. Again, ports on brains burning - whether we are bozos or not - a real thing, we are not making it up.
My team burned 3 ports on the brain in one practice session their first year (Tower Takeover). After some thinking and analysis, we developed a strategy to resolve the issue.
The robot for that season had a DR4B lift with a claw on the end of it. The blown port was connected to the claw motor (at the top of the lift). This motor blew 3 ports in one practice (they kept re-assigning the motor to keep going…).
My analysis is that the standard VEX bearings are made of a non-conductive plastic. As a result, rotating linkages are electrically isolated from the main chassis of the robot and the brain. The standard engineering solution to this sort of problem is to electrically bond the parts. Unfortunately, VEX does not sell bonding jumpers (short wires with ring terminals). Fortunately, you are allowed to use commercial items for bundling or wrapping of cables (<R8> (f) this year).
We used a braided metal sleeve (designed for protecting hoses and wires) around the cables, zip-tying it snugly to both the claw (where the motor was mounted) and the frame (where the brain was mounted). This completely resolved the fried ports. We successfully used a similar strategy during Change-Up. They built a tether-bot with a 12+ foot cable bundle between the halves, fed through a braided metal sleeve. Again, they never fried a port.
My suggestion to VEX is to offer one (or both) of the following products:
- Shielded smart cables (with either a 5th drain wire or a shield conductor connected to ring terminals). This would allow teams to electrically bond remote structures to the main robot frame.
- Electrical bonding wires (short lengths of stranded cable with crimped ring terminals). These could be used to electrically bond around insulating bearings.
Obviously, the bonding wires would be the easiest to implement.
Either of these solutions would allow teams to utilize best practices and electrically bond their structures together for ESD mitigation.
Yay!!! I have wanted these for so long!!!
But I just put in a new parts order…
I guess, the silver lining here is that students not only learn firsthand about the static electricity effect on electronics but, also, about the practical ways to mitigate it, since appropriate protections are not present in V5. Which should make them better engineers!
However, I wish VEX led by example. It has been very frustrating (vexing, may I say) after all these years to see them unwilling to acknowledge design deficiency with V5 in regards to handling ESD and, either fix it with hardware update, or make it legal for students to do so themselves.
I don’t know about others, but it certainly kept me from ordering any additional V5 electronics, waiting for ESD protections to improve.
Coincidentally, just a few days ago, I have ordered a couple of RS485 to TTL modules to communicate with a wired outdoor gizmo, and they were dirt-cheap $1.47 apiece with free shipping included.
Even if it has off-brand TVS arrays and thermal fuses - they still offer better protection for the 485 driver chips than having none like in the V5 Robot Brain. I am pretty sure that, if VEX wanted, they could add similar parts to V5 at way less than $1 per channel.
Even if it still makes financial sense to replace every failed $275 brain (+at least $25 in s&h) rather than adding $10 to the BOM per unit (assuming less than 1 in 30 failure rate requiring replacement), I still don’t understand how it makes engineering and marketing sense to keep making such fragile product that keeps giving bad rap to your brand.
Ha ha ha we learned and we learned about the stupid ESD, alas we are not geniuses yet as ports still burn, no matter how much we learn about it and no matter how much we mitigate. Still bozos. LOL. And by the way, we always reference your awesome collection of posts and we learn from that too so thanks!
Tried that too then started thinking about the theory of it and realized that the components we are trying to bind electrically are actually isolated through their mounting system so no matter how we link the metal structures, we will never create a common ground because the brain mounting holes are electrically isolated from the main board and so are the motor mounts, those are just metal inserts that sit in a plastic casing so the only connection between the electronics is through the cable and never through the robot chassis. Is this wrong?
I think the mounts are electrically ‘isolated’. I think we are still trying to create a path of least resistance that doesn’t involve the electronics…
24T Steel High Strength Gears (276-7572) have just been added to the VEX Website. These are sold as an 8-pack, and can be found here.
These gears are now available for purchase from the US VEX Robotics store, and will be available internationally in the next few weeks as our other offices receive inventory.
ooooooo fancy and very nice
I can only spell CAD and wasn’t able to figure it out on the product page, but would there be enough room on the face to be able to drill a hole that could accept an 8-32 screw (either straight thru or tapped)?
Technically, yes. However…
That hole will not be on pitch and won’t have much material around it.
I imagine these won’t pair very elegantly with the other gears because the diameter is not necessarily in half-inch increments. I could be wrong since I haven’t checked in a CAD file or anything. Anyone want to check? Still, a very neat part that will allow for a greater range of gear ratios.
To remedy this, you can install a nylon bushing held in by friction (drill out a hole to the match the correct OD of the spacer). It’s legal since it’s technically just a spacer. It’ll give more stability to the joint while allowing low friction free spinning
All V5 gears are 24DP, which means there are 24 teeth per inch of pitch diameter. So a 12T gear would have a pitch diameter of 1/2" (12T / 24DP). The 24T gear would have a pitch diameter of 1". The pitch diameter of all the V5 gears are:
12T = 0.5" Pitch Diameter
24T = 1.0" Pitch Diameter
36T = 1.5" Pitch Diameter
48T = 2.0" Pitch Diameter (this was part of the EXP announcement)
60T = 2.5" Pitch Diameter
84T = 3.5" Pitch Diameter
As long as the pitch diameter of a gear is divisible by 0.5", there will be no problems with it playing nice with other gears in the system.
With a minor caveat that the hole spacing makes meshing a 36 and 24 tooth gear a bit difficult.