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 Robotics / RCX / legOS / *179 (-40)
  Re: IS free()'s operation atomic?
 
(...) I agree, free() is not ISR safe. One thread can get preempted after the check but before the store, and a second thread can adjust mm_first_free, making the first thread's check invalid. -Kekoa (25 years ago, 29-Apr-99, to lugnet.robotics.rcx.legos)
 
  IS free()'s operation atomic?
 
Hi all I think that free() operation in mm.c is not ISR safe in multitasking mode. This operation is not keep coherence about value of mm_first_free,is it? ---...--- in mm.c ---...--- // for task safe operations, free needs to be // atomic and (...) (25 years ago, 29-Apr-99, to lugnet.robotics.rcx.legos)
 
  Rom sensor read routine
 
In writing some sensor code yesterday/today (it's 6 am), I passed over the ROM sensor code at 14c0. The documentation has been put in the usual place. The rotation code is pretty simple: the expected state machine, with split points between the four (...) (25 years ago, 25-Apr-99, to lugnet.robotics.rcx.legos)
 
  Re: legOS Network Protocol
 
(...) given (...) lego (...) [ stuff about lego/native collisions ] (...) of a (...) on (...) I was wondering, since people are considering using tags in the LNP frame to signify local to local messages, could we not also use this to "label" non (...) (25 years ago, 23-Apr-99, to lugnet.robotics.rcx.legos)
 
  Re: loading s/w
 
(...) In my brief experimentation with rom_reset(), it does not actually clear the rom- rather it only starts the program over again (in main()). Is this intentional? I get this behavior when calling it from main- when calling it from within another (...) (25 years ago, 21-Apr-99, to lugnet.robotics.rcx.legos)
 
  Re: Rotation sensor bug found
 
(...) This seems the best approach to me too. My problem is I don't know if I am able to do such a thing :-) (...) I know your site and know you've done a LOT of hard work to understand and explain both RCX hardware and original firmware code. Mario (25 years ago, 21-Apr-99, to lugnet.robotics.rcx.legos)
 
  Re: loading s/w
 
(...) That's what I am doing. Markus. (25 years ago, 21-Apr-99, to lugnet.robotics.rcx.legos)
 
  Re: legOS Network Protocol
 
(...) Hmm.. with a little hacking you could certainly detect logic errors. The main problem I think would be writing alternative C-Functions for the H8 assembler, which makes up legOS itself. You'd also need to create a simulator engine for legOS to (...) (25 years ago, 21-Apr-99, to lugnet.robotics.rcx.legos)
 
  Re: loading s/w
 
(...) The first instruction (at 03ae) places the stack in on-chip memory, assuming RAME bit of SYSCR is at its initial value of 1. Why not make rom_reset() disable interrupts, then do its thing? That would be the safest thing to do. -Kekoa (25 years ago, 21-Apr-99, to lugnet.robotics.rcx.legos)
 
  Re: loading s/w
 
(...) Well, if rom_reset() gets invoked near the end of your time slice, ROM has no time to reset the OCIA IRQ vector before the next timer tick. I'm not certain about the order in which ROM sets up data areas and IRQ vectors. legOS freely allocates (...) (25 years ago, 20-Apr-99, to lugnet.robotics.rcx.legos)
 
  Re: legOS Network Protocol
 
(...) Assuming packets without large internal gaps, we could employ a timeout to wait for a packet transmission of unknown protocol type to end. At 2400 bps with 8E1 (LEGO, isn't it?), one data byte has 11 bits, so a space of 1.5*11/2400 s should be (...) (25 years ago, 20-Apr-99, to lugnet.robotics.rcx.legos)
 
  Re: Rotation sensor bug found
 
(...) Excellent idea. This would yield the default settings dead-on. (...) Scaling isn't about the final output. The final output is already in the standard format. Scaling is about shifting the raw sensor values displayed by the firmware six digits (...) (25 years ago, 20-Apr-99, to lugnet.robotics.rcx.legos)
 
  Re: legOS Network Protocol
 
(...) Yes this will be a datagram only protocol for the time being. The LNP will allow us to do things like debugging and remote control. I have also invisioned something like a "shell" running on the legOS that you could either "telnet" in to or (...) (25 years ago, 20-Apr-99, to lugnet.robotics.rcx.legos)
 
  Re: Rotation sensor bug found
 
(...) Why doesn't somebody finish up the decoding of the ROM, specifically the routine at 14c0. This routine takes the raw sensor samples and converts them to usable values, including handling the temperature and rotation sensors. The standard (...) (25 years ago, 20-Apr-99, to lugnet.robotics.rcx.legos)
 
  Re: legOS Network Protocol
 
(...) From what little I remember about the Lego protocol, here are some thoughts. *) On reception, some Lego packets may contain data which look like the beginning of a legOS native protocol frame. Most likely, the checksum would fail (once enough (...) (25 years ago, 20-Apr-99, to lugnet.robotics.rcx.legos)
 
  Re: loading s/w
 
(...) What sort of safety are you referring to? Motors left running? My initial thought was of lost memory or data structures in an indeterminate state, but that would seem to be moot since you are restarting from the ROM, which will have forgotten (...) (25 years ago, 20-Apr-99, to lugnet.robotics.rcx.legos)
 
  Re: legOS Network Protocol
 
(...) The interface is specifically datagram only. Dunno about packet reassembly; I doubt it as the philosophy is minimalism. The main advantage I see in it is the ability to change the degree of checking it does on your behalf to ensure packets (...) (25 years ago, 20-Apr-99, to lugnet.robotics.rcx.legos)
 
  Re: Rotation sensor bug found
 
(...) I suppose we could ask for help also to non-legos owners of RCX and rotation sensors. What if any of us posts a message in the robotics newsgroup asking for some reads of rotation sensors? Raw values can be read with the sandard firmware too (...) (25 years ago, 20-Apr-99, to lugnet.robotics.rcx.legos)
 
  Re: Rotation sensor bug found (maybe!)
 
(...) Exactly. I don't have rotation sensors, either. I think these values were originally gathered from Michael Nielsen's sensors. What's the current status? Is there a patch working for everybody, or do we need some calibration work? It would be (...) (25 years ago, 20-Apr-99, to lugnet.robotics.rcx.legos)
 
  Re: loading s/w
 
(...) rom_reset() does the trick, you'll need to #include "rom/system.h". I'm not sure wheter this is safe when multitasking. (25 years ago, 20-Apr-99, to lugnet.robotics.rcx.legos)
 
  Re: Linux Newbie
 
(...) I seriously recommend Linux to anyone with a computer background- it has been over a year since I've had anything (major!) other than Netscape crash. Of course, it is a pain in the butt, and neither my roommate nor my girlfriend are real happy (...) (25 years ago, 20-Apr-99, to lugnet.robotics.rcx.legos)
 
  Re: Linux Newbie
 
Thanks to Dave and Joel. I looked quickly at those sites, and there are just what I need. I am off to have a closer look now. I realized that Linux isn't required to program with LegOS, but there are other programs I am looking at using as well. (...) (25 years ago, 20-Apr-99, to lugnet.robotics.rcx.legos)
 
  Re: Linux Newbie
 
www.linuxnewbie.org (...) Joel Shafer joel@connect.net (25 years ago, 19-Apr-99, to lugnet.robotics.rcx.legos)
 
  Re: Rotation sensor bug found
 
(...) OK. I was wrong. I should have better analyzed your code... This definitively prove how long still is my way to get my hands on C :) BTW, I wrote an e-mail to Markus but got it bounced back. Mario (25 years ago, 19-Apr-99, to lugnet.robotics.rcx.legos)
 
  HOWTO v 0.1
 
Hey everyone. I'd like to announce that I've posted to the web a basic version of a HOWTO for LegOS. If everyone has a chance, please take a look at it and let me know what you think. In particular, take a look at the about the HOWTO section, as it (...) (25 years ago, 19-Apr-99, to lugnet.robotics.rcx.legos)
 
  Re: Rotation sensor bug found
 
(...) It wouldn't, though. First it gets the maximum of the given value or RANGE_SIZE. That is done to prevent a similar overflow at the low end, even though, with current values, that won't happen. Then, that value is compared against the safe (...) (25 years ago, 19-Apr-99, to lugnet.robotics.rcx.legos)
 
  RE: Linux Newbie
 
Linux is a full blown Operating System, available with full source code. A good place to start is (URL) legOS is built using the same tools that are used to build Linux (GNU compiler and tools, etc.), I don't believe that you need to use Linux to (...) (25 years ago, 18-Apr-99, to lugnet.robotics.rcx.legos)
 
  Re: Rotation sensor bug found
 
Lou, thank you for your reply. (...) This should work. (...) This seems wrong to me because sets all the STATE_n_VALUE to k-RANGE_SIZE. For now I modified ds_rotation_handler() in this way (two occurrences): // if ( IN_RANGE ( STATE_0_VALUE ) ) { // (...) (25 years ago, 18-Apr-99, to lugnet.robotics.rcx.legos)
 
  Experimenting with Visual Basic - Learning Edition
 
Hello: Just thought that I would post a comment regarding Visual Basic and RCX programming. I am new to using Visual Basic as a programming language. But I decided since the Lego Mindstorms System can be controlled by Visual Basic, I would look into (...) (25 years ago, 17-Apr-99, to lugnet.robotics.rcx.legos)
 
  Re: LNP Repost
 
(...) Indeed. I just figured that since the infrastructure would already be there for networking, it would be elegant to use the same for IPC. As you said, they don't actually need to be integrated. Then, there is your point about compiling in LNP (...) (25 years ago, 17-Apr-99, to lugnet.robotics.rcx.legos)
 
  RE: LNP Repost
 
Very true, but lets try hard not to add any more bytes to the header. The smaller the better since the packets are probably pretty small. -Jake -----Original Message----- From: Ben Laurie [mailto:ben@algroup.co.uk] Sent: Saturday, April 17, 1999 (...) (25 years ago, 17-Apr-99, to lugnet.robotics.rcx.legos)
 
  RE: LNP Repost
 
Those are some really good points, but I am still concerned about the complexity and overhead of implementing IPC on the lego. Since resources are so limited it might just be easier to use shared memory and semaphores to communicate. On the other (...) (25 years ago, 17-Apr-99, to lugnet.robotics.rcx.legos)
 
  Linux Newbie
 
Here is a silly question, but you guys are the right ones to answer it... compliment I think :) I need to find a "What the hell is Linux" webpage. I _think_ it is a OS that is user developed, and is common on UNIX systems. I run windows 98 and (...) (25 years ago, 17-Apr-99, to lugnet.robotics.rcx.legos)
 
  Re: LNP Repost
 
(...) For IPC, each (unshared) connection would take 2 ports (src/dest), so 4 bits at least lets us have 7 IPCs (assuming port 0 is reserved as it is in Berkeley sockets, 8 if it is not). I could certainly see having need of more than 3 IPC (...) (25 years ago, 17-Apr-99, to lugnet.robotics.rcx.legos)
 
  Re: Rotation sensor bug found (maybe!)
 
(...) You've got a point here. What if we hardwire STATE_0_VALUE to the following? #define STATE_0_VALUE (ds_unscale(1023U)-RANGE_SIZE) Or, for a more general approach: #define MIN(a,b) (a<b?a:b) #define MAX(a,b) (a>b?a:b) #define STATE_VALUE(k) ( \ (...) (25 years ago, 17-Apr-99, to lugnet.robotics.rcx.legos)
 
  Rotation sensor bug found (maybe!)
 
I think I might have found a bug in the ds_rotation_handler (direct-sensor.c). The problem arises when the STATE_0_VALUE is checked using the IN_RANGE macro. As STATE_0_VALUE is 1023U<<6, which is about the max value for an unsigned, adding to it (...) (25 years ago, 17-Apr-99, to lugnet.robotics.rcx.legos)
 
  Re: LNP Repost
 
(...) Actually, no. On attempt 16, you reserve some more bits further down for the new version number :-) Cheers, Ben. -- (URL) grandfather once told me that there are two kinds of people: those who work and those who take the credit. He told me to (...) (25 years ago, 17-Apr-99, to lugnet.robotics.rcx.legos)
 
  Re: LNP Repost
 
(...) I'd prefer 11111b for broadcast, in keeping with TCP/IP. Cheers, Ben. -- (URL) grandfather once told me that there are two kinds of people: those who work and those who take the credit. He told me to try to be in the first group; there was (...) (25 years ago, 17-Apr-99, to lugnet.robotics.rcx.legos)
 
  Re: LNP Repost
 
I personally can't see needing more than about 7 tasks listening at one time anyway. Keep in mind that the resources on the lego are very very small. As far as reserving an address for IPC that would be fine. We could reserve 00000b for IPC and (...) (25 years ago, 17-Apr-99, to lugnet.robotics.rcx.legos)
 
  Re: LNP Repost
 
(...) I can see this. but it is starting to feel a little cramped on the ports, though. What functionality is port 0 reserved for? Actually, I was thinking of reserving a host address (such as 0x0) for IPC. I'd probably want to have more than 3 (...) (25 years ago, 16-Apr-99, to lugnet.robotics.rcx.legos)


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