Ive been looking at the MiniABB equipped with a Basic Atom Pro 28pin stacked with the SSC32, all for about $125, controlling 52 servos total and a whole bunch of features I’m sure that I dont know about (Im still fairly new to electronics).
The MR-C024 controls 24 servos and also has HMI protocol, something the above products dont. Especially since I’m purchasing digital servos, the 5645s and the 5990s at that, what do you recommend I buy? The MR-C024 is double the cost, half the size and also half the servo control (but I dont plan to put more than 24 servos on a robot). Also, I’m not sure just how important HMI protocol is, dont I require the HMI programming cable for it? And also one last thing, MR-C024 can only be programmed in ROBOBASIC, is that much harder than C or the other languages?
Can you guys please educate me on the differences I should know about and what path you would take here? Thanks.
As I would assume you already know, the MR-C024 is used on RoboNova-1 robot.
It is a nice piece of hardware, but I personally became very frustrated with it. For example the underlying hardware supports I2C and I believe that they use it to talk to an onboard ROM. However you can not gain access to it. Instead if you wish to talk I2C you need to do your own Bit Bang functions in their Basic language. Likewise you do not have access to the hardware interrupts, timers, … When I asked HITEC if I could reprogram the board using C, I was told it was possible, but you would need to unsolder and remove the chip from the board and they did not recommend it… I believe that a few people up on the robosavvy forum have done this. Again I would like to reiterate that this is a nice board and I have seen examples where people have used them to do great stuff. (Mine is still shamefully stashed in a box in the closet)
I like the mini-aab with the Atom Pro. Personally I have found it a lot more fun working with this board. If your project does not require a lot of servos, you can simply use this board without the SSC-32. This was how the TV Brat was implemented. I very much appreciate that BasicMicro has decided to allow the developers to gain access to most of the underlying hardware. They also allow you to program the Atom Pro in C (or C++). Maybe someday we will convince them to export a C library that exposes a lot of their functionality…
Another difference between the two boards is support. I don’t believe that I ever saw any of the Hitec developers (or even customer supprt) monitor these threads and give advice on how to do things correctly or work around issues. Whereas AcidTech from BasicMicro is up here reasonably frequently. This is also true for the developer of the SSC-32 and this code is available for downloading, which makes it easier for us to figure out what is going on and to learn a few new tricks.
I am not sure if this helps you out or not, but just remember it is just my $.02.
The Atom Pro can be programmed in C? How, by changing the Stamp (?) module? That would be interesting! Yes, I’d like a good C lib for the processors as well!
Yes, the Basic Pro IDE comes with the C compiler. In the IDE you simply do a new project and choose C and C++ and use the GNU compiler and then download it to the processor in the same way you download a basic program. You have all of the standard GNU libraries, that are setup for the Renesas microcontroller. What you don’t have available to you is any of the code that Basic Micro wrote. So if you need to do any bit bang functions to do PWM or Serout, you will have to roll your own.
Th 5645 servos are not HMI servos, and are programmed using the HFP programmer. the 5990 are HMI servos and are programmed using a simple serial,cable and free software from Hitec.
The HMI requires a bidirectional interface if you want feedback of position. This means the SCC-32 will not give position feedback., although fine for control. The 3024 will give position feedback but only uses PWM mode(set / read position), not serial mode (set/ read position, speed, current).
The 3024 is normally programmed using Robobasic which is compiled to intermediate code, which is downloaded to 3024 EEPROM, which is rather slow, and also the tools are fairly RoboNova specific. It does have point to point moves, and gyro support built in.
You can change the code in the 3024 flash without changing the chip, and then program in C or asm using either a PWM or serial HMI library for the servos. However in this mode the 3024 is little more than an ATMega128 with servo connectors, so not good value. This is also not supported by Hitec
If you don’t need the HMI position feedback, then I would go with the SCC-32 option, though I use the 3024 because I have a RoboNova. You might connect the 5645s to the SCC, and then connect the 5990s to serial ports either individually or in daisy chain to control and read them.
Now I’m trying to debate whether I’ll really need HMI or not. I do plan to make a very intelligent biped that will be able to grab objects it see’s in its camera. Not only that, but it will be equipped with 3-axis gyros/accels and range finding sensors for avoidance. How important a role would HMI play here?
It is entirely possible to build a good stable biped without HMI or any other method of reading the servos for position/current etc… This may well serve your needs for a platform for the video and pickup project you plan.
Dynamically reading the servos is more related to agility than intelligence, so I was a little surprised to see Gyros/accels on your list, since these also are more related to agilty.
Hiring people isn’t the problem. It’s hiring people that know anything about PIC/Hitachi assembly coding(and don’t expect 80k a year to do it, we don’t make that much from this stuff beleive it or not). The library of MBasic is written entirely in assembly(PIC or H8 depending). We’ve hired(contract workers) on a occasion and so far been very disappointed in what we’ve gotten. I’ve ended up going back in and rewritting almost everything we’ve gotten because what was delivered was pittiful(but cost an arm and leg). We’ve since stopped trying to get contract work done for the most part because of those experiences. As far as backend work it’s basically me and one other guy(Jeff, who is running our beta test group on the 18F parts). If you know some kick ass PICmicro programmers who need a full time job let me know. Note I expect someone at least somewhere in the same ballpark as me.
