Abhishek:
There is just too much jitter in the delays in the pc->mote communication, especially if you use java. Most of this jitter you just can't control (JVM, OS, USB, etc.) Have you considered moving the timing-sensitive code to the mote? Janos From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Abhishek Anand Sent: Monday, June 16, 2008 11:22 AM To: Andrey Gursky; [email protected] Subject: Re: [Tinyos-help] Mote-PC serial speed increasing Hi, I'm facing a similar problem! My protocol requires a strict time control on when the the packets are actually transmitted from the base station. I have programmed by base-station-mote with the BaseStation app in /$TOSROOT/apps/ folder. On the PC, my java program uses a the MoteIF class to send the packets But unfortunately, it takes randomly a value b/w 8 to 25ms for the packets to be ultimately broadcasted thru radio. I mean the call to MoteIF.send(MoteIF.TOS_BCAST_ADDR, smsg); in java takes anything b/w 8-25ms to return. This is causing a lot of problem for me because my application requires fine timing control I'm okay with a delay of 20ms but is there any way to remove the randomness of the time taken? In other words, is it possible to do something so that there is a FIXED gap of few ms b/w call to MoteIF.send and the the commencement of the radio transmission of the packet at the Base-station mote? Regards, Abhishek Anand IIT Guwahati On Mon, Jun 16, 2008 at 9:00 PM, Andrey Gursky <[EMAIL PROTECTED]> wrote: Hi! Thanks Janos for your advices! I've changed the serial speed to 230400 (because of serial speed declarations in GNU/Linux). It works :) After simple test with printf() there is about 1 Kbyte/s :( Than I've changed printf() test application. I supply printf() a string with about 250 characters, then flush(). I could read about 8.5 Kbyte/s. It's really more than standard for IRIS 57600 Kbit/s, but it is still less than standard for other platforms. I've used PrintfClient to get the data. What do you think, is there a bottleneck easy to reprogram? I haven't tested yet how much traffic I can transmit throw ZigBee. If this will not more than 8.5 Kbyte/s then there is no sense to work around serial communication. Best regards, Andrey > Andrey: > > I think the code change you're proposing should work. > > >So atm128 doesn't have speed enough to guarantee 256 KBit/s > >data connection pc<->mote? If one want this, one should > >implement a different platform with another microcontroller? > > There's a good chance that it works. Just give it a try. BTW, I bet you'll never > be getting 250kbps worth of zigbee payload in through the radio... > > >By the way, MIB520 has also a microcontroller on board. > >Is USART of Mote directly connected to FTDI chip or > >throw this microcontroller? > > It's hooked up directly to the FTDI chip. > > >It seems to be not so easy even at the standard serial speed :( > Obviously, 57600bps might not be sufficient to push through all the incoming > radio traffic... > > Janos > > -----Original Message----- > From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] > On Behalf Of Andrey Gursky > Sent: Thursday, June 12, 2008 6:00 AM > To: [email protected] > Subject: Re: [Tinyos-help] Mote-PC serial speed increasing > > Thanks Janos! > > > On the iris, the ubrr0 register is set, at initialization time, to a calibrated > > value for 57600bps. You can change the baud rate by writing this register. > > > > I've found in $TOSROOT/tos/chips/atm128 this code: > > command error_t Init.init() { > if (PLATFORM_BAUDRATE == 19200UL) > m_byte_time = 200; // 1 TMicor ~= 2.12 us, one byte = 417us ~= 200 > else if (PLATFORM_BAUDRATE == 57600UL) > m_byte_time = 68; // 1 TMicor ~= 2.12 us, one byte = 138us ~= 65 > return SUCCESS; > } > > I could add the line like this (or I should seek on to find ubrr0?) > .. > else if (PLATFORM_BAUDRATE == 256000UL) > m_byte_time = ----->15<-----; // 1 TMicor ~= 2.12 us, one byte > = ----->31us<----- ~= ----->15<----- > .. > > > > > This should work with a MIB520, but it is problematic with a MIB510. Should > > you have the former programming board, the bottleneck will probably be the > > interrupt load on the mote in the pc->mote direction. Note that the serial > > stack doesn't buffer outgoing packets (mote->pc), so the app must assume > > a lossy mote->pc link. > > > > I have MIB520 (with usb) :) > So atm128 doesn't have speed enough to guarantee 256 KBit/s data connection > pc<->mote? If one want this, one should implement a different platform > with another microcontroller? > > By the way, MIB520 has also a microcontroller on board. Is USART of Mote directly > connected to FTDI chip or throw this microcontroller? > > There is one post seems to achieve similar goal: the highest speed :) > https://www.millennium.berkeley.edu/pipermail/tinyos-help/2008-June/0342 18.html > > It seems to be not so easy even at the standard serial speed :( > > Could someone point me to reference where I can read about what the atm128x > has yet free to use as quick and reliable communication with PC (SPI, I2C)? > Or the best idea were to use other small design to exchange messages between > PC and ZigBee motes? > > > > > > > -----Original Message----- > > From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] > > On Behalf Of Andrey Gursky > > Sent: Tuesday, June 03, 2008 6:16 AM > > To: [email protected] > > Subject: [Tinyos-help] Mote-PC serial speed increasing > > > > Hi tinyOS-community! > > > > It seems possible (according datasheet) to use USART of ATmega128x in >57600 > > speed mode. Thus ZigBee functions of 250 Kbit/s it would be nice to have this > > speed also between basestation and PC. > > Does somebody know exactly, whether it would be as of some other reasons not > > possible? Or have I to alter configuration in .../chip/atm1281 to get this > > working? > > > > > > Best regards, > > Andrey > > > > P.S. Particularly I'm interesting in iris-motes. > > _______________________________________________ > > Tinyos-help mailing list > > [email protected] > > https://www.millennium.berkeley.edu/cgi-bin/mailman/listinfo/tinyos-help > > > _______________________________________________ > Tinyos-help mailing list > [email protected] > https://www.millennium.berkeley.edu/cgi-bin/mailman/listinfo/tinyos-help > _______________________________________________ Tinyos-help mailing list [email protected] https://www.millennium.berkeley.edu/cgi-bin/mailman/listinfo/tinyos-help
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