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Messages - LukeZ
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271
« on: July 29, 2020, 09:35:42 AM »
Thanks for the link to the eBay boards, and on closer examination it looks to me that the pro mini boards Jürgen mentioned will also work, there are minor differences but overall it's the same footprint. I made a note about these in the description on the Downloads page. That is a good point about copper thickness, you're right OSH only offers thicker copper on their thinner board for some reason. I did a rough calculation for the smoker portion of your board and even with the 32 mil trace width you use, and even at 2 oz copper, the maximum calculated limit of those traces is only 1.7 amps. At 1 oz copper it drops to about 1 amp. I don't recall exactly how much current the generic Taigen/Heng Long smokers pull, the heating element itself was about 1/2 amp but then there is the current of the motor as well. ( Actually it seems you measured one at 2.1 amps once) It highlights yet another of the many aspects of board design, aside from merely squeezing everything into a finite area. This is why we often use planes rather than only traces for high current signals, or polygons if we don't have the luxury of covering the majority of a board layer with copper. Another method is to run double traces, one on top of the board and one on bottom, this effectively doubles your copper thickness without increasing the trace width, though of course you need to have a clear run on both the top and bottom for that to work. Component placement also helps, we can try to locate high current outputs/transistors as close as possible to the incoming power source, in order to keep trace length short. We used all these and more on the original TCB, which was produced using only 1 oz copper. However I will say, that although more difficult to assemble, an SMD board does make life easier in other ways, for one we need fewer traces on the bottom of the board, and fewer interruptions generally on the bottom due to fewer through-holes, so this makes it easier to to have large power planes on the bottom layer. In your case I rather doubt it will be an issue, but you can keep an eye on your boards for signs of overheating. There is still a little room to increase power handling on your design but I'd just use it and see what empirical evidence tells you before feeling like you should launch into an overhaul.
272
« on: July 26, 2020, 01:45:57 PM »
Jerry just wanted to let you know that I put a link to this project on the Downloads page under the Accessories section. I should have done that before! It really is a useful little device, cheap to build, and lots of people have 3D printers now so I hope others will get to try it out.
273
« on: July 26, 2020, 01:43:40 PM »
Jerry this is really great, I read through your write-up and examined the board in Eagle. I can tell you put a lot of time and thought into this, I was surprised to see you even kept the same mounting hole dimensions and connector layout! Thanks for being so thorough in the documentation and creating the bill of material, etc... I have created a new section on the Downloads page called "Member Designs" and yours is the first design to be posted, and I've included links to the various board files and resources. I also put a link to your board on OSH Park under the OP account. I noticed you mentioned trouble getting boards of adequate thickness from OSH Park, but although they do offer a thinner option, I believe the standard selection is 1.6mm thick which is what you recommend and which I agree is better. I did a test order at OSH Park and it looks like it comes to about $40 US for 3 boards, which seems reasonable. However SEEED is also a good place to order them so that is fine as well. This may have already been mentioned earlier in the thread, if so forgive me, but did you ever find any other Arduino Mega boards besides the RobotDyn that uses the same footprint? Jürgen mentioned the generic Chinese "Mega2560 Pro Mini R3" boards which look very similar but I can't tell for sure if they are actually the same footprint or would be compatible with your shield. Anyway, if there are others you know of that would work let me know and I'll list them in the comments. Over the years people have built quite a few different kinds of shields and partial shields, or assembled mostly functional TCB substitutes from various parts, but this one I think is the most complete project so far. It maintains all the functionality of the original board, can be built without advanced soldering techniques, and is well documented. I really do hope you get to experience the enjoyment of seeing someone else build and run your design!
274
« on: July 21, 2020, 04:02:26 PM »
I am looking forward to seeing what you create!
275
« on: July 19, 2020, 08:11:20 AM »
I should add - you will need to define your aux channel as "Analog" even if it is 2 position switch, otherwise the aux channel will not appear in the list of triggers available to assign to the RC Output function. But it is fine to do this.
276
« on: July 19, 2020, 07:31:44 AM »
The protocol is quite simple, for the sound card each "sentence" consists of 5 bytes: struct DataSentence {
uint8_t Address = 0;
uint8_t Command = 0;
uint8_t Value = 0;
uint8_t Modifier = 0;
uint8_t Checksum = 0;
};
You can see how the bytes are unpacked on the Serial tab of the Sound Card firmware. Commands are defined in the SoundCard.h file. On the TCB side you can see the mapping between TCB functions and Sound Card commands in OP_Sound.h and you can see the very simple functions for sending the sentence over the serial port in OPSoundCard.cpp. The process is basically the same for communicating with the Scout and Sabertooth serial controllers, except those use 4 byte sentences (Address, Command, Value, Checksum) - they don't have the "Modifier" byte. The Address is unique to each device and prevents the Sabertooth from responding to commands for the sound card, or the sound card responding to commands for the Scout, etc... The addresses are hardcoded, here is the current list: Pololu Drive - 10 (0x0A) Pololu Turret - 13 (0x0D) Sabertooth Drive - 128 (0x80) Scout Drive - 131 (0x83) Scout Turret - 132 (0x84) Sabertooth Turret - 135 (0x87) OP Sound Card - 218 (0xDA) If you are just re-creating the sound card where the only difference is the way acceleration/deceleration is handled, just give your device the same address as the OP Sound Card (218). In other words, this is simply an exercise in modifying the existing OP Sound Card firmware, as you have already discussed. If you are creating a device with all kinds of new features, you will have to give it a different address and then define your commands to do whatever you want (value and modifier are optional). However, I think the problem you will quickly run into is that you will want to issue commands that the TCB doesn't have and doesn't know about (in other words, new Functions). Adding new functions to the TCB requires not only changes to TCB firmware but also changes to OP Config, changes to the wiki, etc, etc... So that I am probably not going to do. You may find yourself creating a whole new TCB, or maybe a whole new product entirely. Even so, I hope looking at the code from this project will be useful to you.
277
« on: July 19, 2020, 06:49:30 AM »
Yes of course, use one of the "RC Output x - Pass-through" functions and assign it to an aux channel, such as a 2 position switch on you transmitter.
278
« on: July 17, 2020, 08:50:03 AM »
Hi Luckowner, thanks for bringing those threads to my attention. It seems some progress has been made on the PJRC forums with sound sampling, although I see for now it only works with RAW files. It would be ideal if Paul from PJRC can include this feature into his official Audio library, and maybe he will be able to do so eventually.
Unfortunately I have no time at all for development right now, so I can not be of much help to you. You seem to have come quite far already, I think if you stare at the code long enough you can see what I have done and probably figure out how to make the changes you need. Start small, make one change at at time and test, and through slow experimentation my experience is that you can eventually go quite far. I'm sorry I can't be of more assistance, but I wish you good luck and please let us know if you have success!
279
« on: July 16, 2020, 12:06:25 PM »
Thanks for the Gerbers, I took a look at them in KiCad. You have done a professional layout job, I am impressed. You said you used this project for an exam, are you an engineering student? I think you deserve a good grade, I hope you get one!
I look forward to inspecting your firmware and I will be happy to host it on the OP GitHub, it should be possible to make you a contributor so you can maintain that repository. It also should not be a problem to add an entry to OP Config Firmware tab so users can select your firmware for download/flashing.
As you say, with all the microcontroller advancements constantly being made there are now many tantalizing possibilities, but people who possess time and skill are necessary to realize them, and in so far as there is no great financial reward for doing this work, these must also be special people who have other motivations (educational achievements appears to be a good one!)
Thank you for the offer to help with board layout, I will keep it in mind and let you know if I can get the design to the layout stage.
280
« on: July 13, 2020, 04:47:48 PM »
Hi Jerry, sorry for the slow reply. The ZTX651 looks like it should work fine, though I note the order of the pins appears to be reversed from the BC337, so you will just want to double check and probably flip it around when you install it.
Also, to get the full 2 amps out of that transistor you will want to reduce the base resistor to around 200 ohms, this is R4 on your schematic.
Let us know how it works!
281
« on: July 12, 2020, 09:08:47 AM »
Hello Kim! Your design is extremely impressive and interesting. Thank you for sharing! It is very educational to see the design choices you have made and the components you have chosen, I think a lot can be learned from this design. I see you have changed some of the pins in order to manage the onboard main motor drivers, it looks like you had to sacrifice PWM on the Hit Notify and Aux outputs?
I may be willing to make some changes to OP Config on your behalf but it is something I will want to think about and I may not do it right away. Of course it would benefit you and your club but the extra options in the documentation will only confuse all the hundreds of other people who already have a TCB, so I have to weigh these things carefully.
In the meantime it would be great if you could make your project open source, including the firmware for the Arduino Mega, and board files and bill of materials for your shield. This could be hosted on GitHub. If you are able you can make a fork of the TCB firmware with your changes on your own GitHub, or if you prefer you can provide me the source code and I can fork it myself and host it on the Open Panzer GitHub page.
You may be interested to know that in fact all the functions could be simplified onto the Teensy 3.2 alone, eliminating the need for the 2560 altogether. In other words, we can combine both the sound card ability and all the rest of the TCB functions onto just the Teensy, including onboard main motor drivers as you have done, so that in the end we have a complete single board product. The 3.2 has barely just enough pins if we use some shift registers! I have started writing code for this but it is not yet complete and I don't know when I will have the time to finish it. I haven't even started on a board design. I am not spending much time in development this year due to other commitments, but if the project were to be revived someday I think that would be the way to do it. But for now it is just an idea.
282
« on: June 22, 2020, 01:04:41 PM »
The Quicruns should work well. Let us know if you have any more issues!
283
« on: June 22, 2020, 07:32:52 AM »
Hi Steve, I just did some Googling and it does not appear this ESC has the option to disable brake. The REV NO/OFF (should be "ON"/OFF) jumper appears to either disable reverse completely or else enable it, but from user reports has no effect on brake. Also some users report that max reverse speed is limited to some amount less than forward speed. It would seem this is not going to be a good choice for use in tanks, I would recommend looking for a different speed controller. There are recommendations in the Wiki, both for standard RC controllers as well as serial controllers (more expensive, but easier to wire and with more options in terms of current handling). Here is an inexpensive RC ESC from AliExpress that can do drive two motors from a single controller. The X-Car 45 ESCs were very good choices but they seem to be out of stock at Hobby King right now.
284
« on: June 15, 2020, 08:05:10 AM »
DigiKey in the US still shows 500 in stock but they also indicate that it is an end-of-life part. Mouser in the UK has an alternative that should work, it is 0.2mm larger in width but I don't think that will matter: 667-EXB-S8V151J
285
« on: June 04, 2020, 03:00:59 PM »
Sorry for the slow reply, but yes that is correct. A very few peripherals are easy to connect, namely the receiver (assuming iBus or PPM, sBus requires another component), ESCs, and any servos you may happen to be using, though most people don't. Also the Benedini is easy to connect. By easy what I mean is you just wire it directly, as described on the first page of this thread: Testing TCB Firmware with Stock Arduino Mega But everything else (lights, mechanical recoil, IR stuff, etc) will require other electrical components in addition to the Arduino, and at that point you are looking at making your own mini-circuits or using some kind of adapter board as some have described in the aforementioned thread. If this is your first foray into Arduino world this is not a good project to start on, but if you already have experience then you can try it so long as you don't mind tinkering and blowing time and money! If you do decide to experiment in that direction the thread I linked to above would be the best place to continue that discussion.
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