Wiki

[technik3k]

Reserved for V5 Rotation Sensor

VEX "Coming Soon" Page

We have a winner. It’s an absolute magnetic encoder, can spin infinitely in either direction, and can accept a pass through HS shaft.

VEX "Coming Soon" Page

Neither. It uses a different technology. It remembers position only within the 0-360 deg range, but can also work like an encoder and provide a continuous position and velocity. Ninjaed by Art…

[technik3k]

Reserved for V5 controller information, tips, and tricks

https://help.vex.com/article/16-how-to-update-your-v5-wireless-controller-firmware

https://help.vex.com/article/11-pairing-wireless-controller-to-the-brain

https://help.vex.com/article/36-how-to-calibrate-the-v5-controller

https://help.vex.com/article/15-how-to-reset-your-controller

Scuff controller add on for V5:

https://challenges.robotevents.com/challenge/94/entry/6044

Add on to V5 controller

Since so many people have been asking in this thread recently, here’s a .zip containing all the parts in STL format:

v5_scuff_controller.zip (2.7 MB)

Issues: (check if this is still the behavior)

Are you limited to just a few V5 Controller buttons commands?

We can only send a new line of text to the controller every 50mS due to the relatively low bandwidth channel we have between brain and controller. If a call is made to controller.screen.print before 50mS has elapsed from the previous call, we call task::sleep on that thread until the 50mS requirement has been met.

Using Controller’s Screen to show something

With PROS, you have to delay between each command by 50ms. If you don’t, the commands you send will not be forwarded to the controller, which only updates every 50ms.

I believe VEXCode automatically inserts those delays in the controller commands for you.

Controls (move to programming section later):
Best joystick controls for drive train?
Tank or Arcade???

Controller troubleshooting dashboard:
V5 controller don't respond to the programming

[technik3k]

Reserved for V5 custom cables how-to

How to Use the V5 Crimping Tool - VEX Robotics Knowledge Base

Ports on Brain not working

Actually it’s explicitly declared legal in the game manual now, rule :

Custom V5 Smart Cables are allowed. Teams must use official V5 Smart Cable Stock but may use commodity 4P4C connectors and 4P4C crimping tools. Teams who create custom cables acknowledge that incorrect wiring may have undesired results.

Ports on Brain not working

As someone who has been crimping Category cable since well before V5 was released, only recently did I finally have the chance to try crimping V5 cables.

What I can say beyond a shadow of a doubt is that VEX’s crimping tool, with a plastic die, is utter garbage. I had several failed crimps, causing the Brain to simply not recognize connected motors. When I did a sanity check with a crimping tool I used for actual Category cabling (with a metal die, just like every crimping tool worth anything), every single crimp worked (and yes, I used the exact same technique).

So, for all I know, the incidence of issues with custom-crimped cables but not factory-crimped cables could somehow be related to the crimping tool. Your mileage may vary, but I can confidently recommend even this $10 crimping tool over VEX’s. You can even get a whole crimping kit, complete with cable tester , for less than the price of VEX’s crimping tool (I can confirm the crimping tool in this exact kit worked perfectly on V5 cable).

TL;DR Try using a real crimping tool in the future. Testing your cables with a cable tester before use is a good idea too.

More V5 smart cable details

V5 Smart Cables vs Commercial Cables

4P4C refers to the connector, also known as RJ9,10, 22.

The cables themselves are custom specified for the load of V5 devices. A standard 4 wire flat cable with 26 awg with may work, but it won’t be ideal. And it’s ok for testing purposes but know you’re accepting responsibility for all the risks it entails.

It’s not legal for competition.

V5 Cables

Aside from the rules stating that V5 smart cables must be used for competition. Not all cables are created equal, here is a comparison, I don’t have specs for either the VEX cable or the random silver 4 conductor phone cable I had, but there’s a significant difference.

V5 Cables

Does anyone know what gauge wire is used in the v5 smart cables? It appears to be 24 awg from @jpearman 's picture, but I’d like to be sure…

To be clear, you may not make your own cables for competition. VEX Cable stock is labeled with V5 logo, so it can spotted during inspection.

[technik3k]

Reserved for V5 in-depth system architecture overview

https://www.vexrobotics.com/v5-architecture.html

The PROS of PROS

This is high level system architecture.

VEXCode get Run Time function?

New Products - December 2019

raw message rate for the inertial sensor is 50Hz. Three wire port (ADI) is 100Hz. Motor is 200Hz, but data is still only available to user code at 100Hz as explained by @hotel.
I’m very skeptical about the double integration being able to reproduce accurate results, but will be happy if someone can prove me wrong.

Defining three wire devices in text

Move to separate RS485 entry later:

Smart Ports Power Wire

This is mainly aimed for @jpearman. Is there any way to provide power to a DC device through a smart port by taking a smart cable and splicing up one end? I’m trying to find a way to power LED lights from smart ports so that I don’t have to waste a legacy port.

VEXcode V5 Text Preview

You can already use VEXcode (and VCS) to interface to custom electronics using a smart port as a generic serial RS485 port. There’s only a C API at the moment, and little documentation, we will probably add a C++ API before next season. Contact me for more details and I can provide some sample code.

Move to programming / multitasking section later:

Help with Task Programming

The VCS/VEXcode scheduler is very similar to the ROBOTC scheduler. There are some differences due to the fact that ROBOTC was running as a virtual machine and had more control over when exactly the task switching could occur, however, the concepts are very similar. startTask( myTask ) becomes vex::task taskId( myTask ) wait1Msec(10) becomes task::sleep(10) AbortTimeSlice() becomes task::yield() and so on. (and I fixed the broken links in the original topic)

Trying to multitask in Vex Coding Studios for User Control

Here is some example code. It’s from VEXcode but should work in VCS as well. It uses additional tasks for drive and controlling a motor with one button. #include "vex.h" using namespace vex; // A global instance of vex::brain used for printing to the V5 brain screen vex::brain Brain; // A global instance of vex::competition vex::competition Competition; // define your global instances of motors and other devices here vex::motor leftMotor( vex::PORT1 ); vex::motor rightMotor( vex::P…

Move to programming communication section later:

VEXcode V5 Text Preview
Wireless Uploading and Terminal Usage to V5 Brain (multiple posts about V5 communication)

Possible problem due to order of initialization of 3-wire port Brain.ThreeWirePort instances:

Memory Permission Error

[technik3k]

Reserved for V5 in-depth system troubleshooting topic 1

Motor commands and dynamic power limiting information:

How does the decreased current affect the robot when using more than 8 motors

vexos 1.0.9 uses a different algorithm than versions 1.0.8 and earlier. 8 or less motors are still capped at 2.5A. 9 or more are capped as follow, remember this is current at the motor not current from the battery, 9 2.39A 10 2.29A 11 2.20A 12 2.12A 13 2.04A 14 1.98A 15 1.91A 16 1.85A 17 1.80A 18 1.74A 19 1.69A 20 1.65A However, those values are only valid if user code has not set current limit lower on one or more motors. If that has happened we take the user specified lower motor curren…

How does the decreased current affect the robot when using more than 8 motors

so most of the time teams are not sending a voltage to the motor but rather a requested velocity. Even when the motor is told to stop, it may be using a significant amount of power depending on the brake mode of the motor. The current limiting happens inside each motor, even when we limit continuous current to 2.5A, the transient current can be much more than that and the motor needs to respond quickly to these changes. Individual motors don’t have knowledge of what all the other motors are …

V5 motor configuration upon reconnect

It’s a feature (bug really) of PROS. vexos keeps the configuration for flags like reverse if the motor is not present when user code starts or is unplugged, however, PROS doesn’t send it though on startup if it thinks there is no motor, VEXcode however does. The things we keep backup values for are brake mode encoderUnits gearset reversed currentLimit voltageLimit One reason for keeping these values is safety, I didn’t want a motor running at full power when user code had aske…

V5 motor configuration upon reconnect

That’s correct, the reverse flag is handled by vexos and not sent to the motor, it’s much easier to handle things like updating the current motor position when user code changes the reverse flag while the motor is running (why you would want to do that I don’t know, but some of these design decisions were taken more than 4 years ago and based on robotc functionality). yea, PROS always validates the the correct type of device is on a given port before calling into vexos

[technik3k]

Reserved for V5 in-depth system troubleshooting topic 2

Important information about event callbacks implementation and its limitations:

Help with spinToPosition/rotateto command

event registration should only be done once, move these outside of the while loop.

Released Functions are not working as expected

Does old callback get erased when I set new callback function?

No, callbacks for an event should only be registered once, registering an additional callback will cause both to fire, registering a null pointer will not free resources.

Callbacks

It does consume additional resource, event handlers should only be registered once, if you register either the same or an additional callback the event will call both handlers.

On V5 each event handler is a thread blocked on a semaphore, when the event fires, vexos released the semaphore allowing the thread to run, the thread calls the user registered callback.

There is currently no way to unregister an individual event handler.

On IQ, which uses the same core functionality in VEXcode, we don’t have enough memory to dedicate a thread to each event so we have to use a thread pool instead, this limits the number of events that can simultaneously fire and be serviced.

Callbacks

yea, I set the limit at 100 events. Some are registered when you create, for example, an instance of a competition object. If you have some tasks, that limit is reduced, limit for tasks is 128, but as an event also runs as a task it uses resources for both.

Callbacks

[technik3k]

Reserved for V5 in-depth system troubleshooting topic 3

[Connor]

Reserved for general programming tutorials

Installation Tutorial (VEXCode)

Interface Walkthrough (VEXCode)

Variables and Functions (VEXCode)

Programming Arm and Claw (VEXCode)

VEXCode knowledge-base article:
https://kb.vex.com/hc/en-us/categories/360002333191-V5

[Connor]

Reserved for Driver Control

Driver Control Tutorial [Arcade] (VEXCode)

Slew Rate

Slew Rate with P controller

Slew rate is a programming technique to prevent motors from being overworked by gradually changing to different motor targets, instead of directly setting them. For example: Without a slew rate controller, you might set motors like so: motor[3] = 0; motor[3] = 127; This can be harmful to the motor controllers, so you can ease their strain by doing something like this: motor[3] = 0; motor[3] = 10; motor[3] = 20; … motor[3] = 127; Note that no one actually does slew rate like that, it’…

C++ Methods? Tasks? Slew Rate

In terms of how I might approach this using C++, I would probably subclass motor to add additional variables needed to handle slew control. namespace vex { class slew_motor : public vex::motor { friend class smart_motors; private: short motor_cmd; short motor_req; short motor_slew; public: slew_motor( int index ) : motor( index ) { motor_slew = 10; motor_cmd = 0; motor_req = 0; }; ~slew_motor…

[Connor]

Reserved for Macros

Two mode Button Toggle Example (ROBOTC, but easily convertable to VEXCode and PROS)

How do you make a push button work as a toggle switch using PLTW natural language?

bool enable = false, btnState = false; while(1){ enable = sensorValue[touch] && !btnState ? !enable : enable; btnState = sensorValue[touch]; if(enable){ //do } else { //do another thing } wait1Msec(10); }

[technik3k]

Reserved for Joystick control scaling, deadband

Exponential Tray Programming

Does anyone have any sort of guide to programming motors to either speed up or slow down exponentially using RMS C++? Specifically using a potentiometer. We would like to try and implement something like this for our tray.

Arcade and X-Arcade Drive using full range of joystick without clipping

Well I found out how to add tables so I figured I’d put the Arcade drive equation here with the tables showing some values for different joystick positions. The X-Arcade tables are interactive so they are still in HTML form found at the github link above. If using joy and/or motor ranges that are not -127 to 127 then the 127 in the equations changes to the joy value and the output value must be scaled to the motor range. Arcade Drive Equations Extrapolated from Arcade function These equation…

Custom Curving Thread and Example (VEXCode)

VEXCode Joystick Curving

Hello, today I will be discussing Joystick Curving in VEXCode, inspired by Pilons 5225A. Example Code for VEX Clawbot: turningCurve = 5; turningRed = false; forwardCurve = 10; forwardRed = false; //graph of red and blue lines from 5225A here //https://www.desmos.com/calculator/sdcgzah5ya int curveJoystick(bool red, int input, double t){ int val = 0; if(red){ val = (std::exp(-t/10)+std::exp((std::abs(input)-100)/10)*(1-std::exp(-t/10))) * input; }else{ //blue val = std::exp(…

[technik3k]

Reserved for Callbacks (and Tasks) discussion

VEXcode for experts

you can. I’ve never really talked or explained events much. We use them internally for things like button presses using function on other classes, but you can create you own events and choose when to use them. For programmers coming from blocks, this should be quite familiar, although many of the places they are used in blocks should really be using function calls instead. if you have a function like this. void eventHandlerA() { static int event_count = 0; Brain.Screen.printAt( 10, …

How do I use the controller button pressed command

yea, this is used when polling the button, it returns a boolean indicating if the button is currently pressed or not. Controller1.ButtonA.pressing() These are used when you want your code to be event based. Controller.ButtonA.pressed( callback_pressed ); Controller.ButtonA.released( callback_released ); A callback used an an event is running in its own thread, that means you can block using time consuming code or a while loop if you really want to, for example, this code using namespace…

[technik3k]

Reserved for PID Control

PID Tutorial and Examples (VEXCode)

VEXCode PID Tutorial

I will be allocating this thread to answering any questions in regards to the tutorial Fair Warning: I am unsure if I have the positive and negative motor values correct, as this is all done on the top of my head. So If the robot is continuing to go even after the lateral position is reached, change error = averagePosition - desiredValue; to error = desiredValue - averagePosition; If the robot continues to go even after the turning desired is reached, change turnError = turnDifference - d…

If you are planning on using PID on arms, add Gravity Compensation or else the PID will not work properly:

Weight Negation (Gravity Compensation) Tutorial

Hello everyone! As I am working on my robot, I have to think about how to program my robot in such a manner where the robot is almost capable to hold its own position without the need of additional elements. Basically speaking, PID is built in such a manner where it doesn’t take consideration of weight, but it is essential in going from point A to point B with the extra ability to react against external forces. So, what we need to do is create a simple convenient algorithm to negate weight to b…

PID Example (ROBOTC)

What is a PID controller?

The p part is proportional, or what we nickname “error”. error = desiredValue - currentValue. This is a position, or delta x So if you get the derivative of error (which error is a position, or delta x), you will get speed (error - previousError). So, you can use the this to help correct if the robot is moving too fast or too slow due to external sources like additional unknown friction or battery crapping out. How the derivative is applied in code is by error(current error at the moment) - p…

PID for Autonomous in Vex Coding Studio

[technik3k]

Reserved for Simple Driving PIDs

Very Simple Very Accurate Chassis Control Code Release

Most everyone struggles with accurate base control in auton. At the highest level, 5225 developed a 3 tracking wheel solution that allowed them to set the world record in programming skills last year, and a handful of teams including 8059 and 139 have replicated their “odometry” based on a document they released last year. Team 5225 Introduction to Position Tracking Document But at a less extreme level, for people just looking to take a step up from move.relative you may like the base control…

Drive Straight PID Loop

I think this worked. This was for encoder backs, so you will need to change nMoterEncoder] to SensorValue() for OSE’s. // function to run drive motors for specified distance in units defined by WHEEL_DIAM then stop the drive motors // +dist = forward, -dist = reverse. void driveDistance(int dist) { nMotorEncoder[drive_LF] = 0; // reset the ime values to 0 nMotorEncoder[drive_RF] = 0; driveLastError = 0; // update driveLastError driveTarget = fabs(dist/(WHEEL_DIAM*PI) * ENCODER_TICKS); // …

Exiting a PID loop

I was very happy to see that almost every important aspect of the robust PID algorithm was already covered by many people. The most important thing to know for PID exit condition, is whether it is intended for user control or autonomous. In case of the user control - PID shouldn’t have its own while loop, but the main while(true) loop that has all the code for checking user inputs would call PID function once in 10-20 mS and let it determine necessary motor power. Variables like accumulated in…

[technik3k]

Reserved for Debugging Output discussion

TBD

[technik3k]

Displaying Images on V5

Animated GIF Demo (VEXcode)

Hers’s another demo that can be built with VEXcode. It’s not very well developed and uses a couple of C API’s that we don’t usually expose that were added to vexos 1.0.5. I’ll also explain a couple of more advanced aspects of the setup in another post later, specifically how to allow VEXcode access to more dynamic memory than is available with the default project build scripts. output looks like this. [gifdemo] and uses this animated gif. [world] You can display more than one gif by creat…

Drawing Image on V5 Screen

Sorry I neglected to state I was using VexCode C++. I have looked at some things on the forum and came up with this code #include "vex.h" using namespace vex; // A global instance of vex::brain used for printing to the V5 brain screen vex::brain Brain; int main() { Brain.Screen.drawImageFromFile("cube.png",20,20); while(1) { // Allow other tasks to run this_thread::sleep_for(10); } } Unfortunately this will not draw the image.

Having troubles displaying gifs

Did you include “vex.h” and “gifclass.h” at the beginning of your program? See attached example in this topic: Animated GIF Demo (VEXcode) vex::Gif class is not a part of the default VEXcode API: https://api.vexcode.cloud/v5/html/annotated.html PNG and BMP images can be drawn with drawImageFromFile(): https://api.vexcode.cloud/v5/html/classvex_1_1brain_1_1lcd.html#ac1a069baa3212a8c697d70c8fa8e5187 See example here: Drawing Image on V5 Screen

Display image on V5 using vex code

A Guide to Changing Program Icons

A guide to icons on the V5 When you upload a program to the V5, you may notice that the icon for it corresponds with what program you used to code it in. But you’ve probably wondered at some point how to change the icon, right? Well here’s a guide on how to do so, wether you code in PROS or VexCode (but it still requires PROS either way). How it works But first, let’s get into how it works. VexOS looks for the icon you specify in the .ini file uploaded to the brain when uploading your program …

[technik3k]

Accessing Files on SDCard

SD Card Help

Here’s a simple example showing how to use the VCS SD card save and load file API. This saves some information into a file called “test.h” on the SD card and then reads it back again. #include "robot-config.h" // storage for some information to save uint8_t myTestData[ 100 ]; uint8_t myReadBuffer[ 1000 ]; int main() { // set the test data to something detectable for(int i=0;i<100;i++) { myTestData* = i * 2; } // write test data to SD Card int nWritten…

SD Card Help

Here, this is what it should be #include "robot-config.h" // storage for some information to save uint8_t myTestData[ 100 ]; uint8_t myReadBuffer[ 1000 ]; int main() { // set the test data to something detectable for(int i=0;i<100;i++) { myTestData[i] = i * 2; } // write test data to SD Card int nWritten = Brain.SDcard.savefile( "test.h", myTestData, sizeof(myTestData) ); // did that work ? if( nWritten > 0) { // display on screen how …

SD Card errors

the sdcard functions all require a buffer pointer, not values like you are passing. If you really want to write binary data, it might be something like this. int x = 23; Brain.SDcard.appendfile("file", (uint8_t *)&x, sizeof(int) ); to write the values as text, you need to convert to a string. int x = 23; char buffer[32]; sprintf(buffer, "%d", x ); Brain.SDcard.appendfile("file", (uint8_t *)buffer, strlen(buffer) ); make sure the file exists if you want to use appen…

Error reading from sdcard

Differences in the SD Card commands bug

What SD cards are supported for the V5 Brain?

[technik3k]

Autonomous Mode Selectors

WalshBots Autonomous Feature Selector

James Pearman posted an example of autonomous selection using the V5 Robot Brain. It allows up to eight different routines to be selected before start of a match. We have extended this to allow the buttons to select features to be enabled or not, for example shoot preload or not. It also allows to select the starting tile and alliance. Attached is an example program and brief description. Thanks James for being an awesome teacher to all! If there are bugs, please let me know. Be sure to cr…

VEXcode Button Generator

Hey everyone, I’ve been playing around with a program that builds rectangular buttons onto the V5 screen and I think it has turned out pretty nice. I initially made it to make it quicker to build our autonomous selectors, but the more the program expanded the clearer it was that it could help make a lot of projects simpler and faster (though not necessarily for use in VRC). As a result, I’m releasing the code for anyone who wants to use it. disclaimer: Right off the bat, know this program has…

Pre-Made VEX V5 PROS Auton Selector

Check out this VEX V5 Auton Selector made using LVGL. Check it out here. [67626102-d9e1d080-f814-11e9-84cd-63a44e6a35af] Lemme know what you think.

Auton Selector

Here is a basic example I of an autonomous selector in Vexcode… int autonToRun = 0; class Button { public: int x, y, width, height; std::string text; vex::color buttonColor, textColor; Button(int x, int y, int width, int height, std::string text, vex::color buttonColor, vex::color textColor) : x(x), y(y), width(width), height(height), text(text), buttonColor(buttonColor), textColor(textColor){} void render() { Brain.Screen.drawRectangle(x, y, width, he…

LVGL Auton Selector with Okapi chassis and Pathfinder Auton Example

For those interested, I’ve updated the Okapi/Pathfinder example to use PROS 3.2.1 and OkapiLib 4.0.3. The auton selector is still the slightly modified 5090Z version. Prior versions are available if you look under the “tags” option on GitHub. Many of the answers I provide are tested here so you’ll see how to limit voltage for motors, toggle speed, joystick text and rumble, auto switch to a different tab, and multiple profile controllers. This update was prompted by questions I see on how to …

[Connor]

Position Tracking/Odometry

Position Tracking/Odometry Tutorial

Hello! I will be allocating this thread to odometry, as requested by many. Because I do not have a robot with me, I have utilized Roblox Studio to help me figure out and test the code (then translating it from lua to C++). I am pretty new to odometry, but I am able to figure out the gist by teaching myself and trial/error (as what @Cody said, doing is the best teacher ). So if/when I have the time, I will be posting tutorial videos on position tracking and odometry. If you need any help l…

[Connor]

#includes in C++

#include files in VEXcode

How would I go about using #include to include other header or source files in my VEXcode project? When I make a new source file and include in it vex.h (so it can access my motor ports) and then try to include that file in main.cpp it gives me errors like "you are redefining “Controller 1” and stuff like that. I am trying to put all of my autonomous routines in separate files. If I was to put an autonomous routine in a separate file should it be a .h or a .cpp file and what directory should …