Baud rate 38k4??

AJI

Ok just jot a psc for my robot and need help

when i chnge the baude rate to 38k4. What do i put in the serout for that baud rate????


Serout 15, ????, [noparse][[/noparse]coman dstring]

what does 38k4 mean??··· 3840???

And why do i have to make the baud rate befor any change

serout 15, 396+$8000,[noparse][[/noparse]comand string]

allanlane5

I believe baud rate "38K4" is equivalent to 38,000 baud, or 3.8 times 10 to the 4.

On the BS2, the equation is: INT(1,000,000 / baud rate) - 20

So 1e6 / 38e3 == 26, -20 == 6.

1e6 / 26 == 38,461 baud (exactly). So you can't get exactly 38,000. But 38,461 is only 1% off, so it should still work.

Final answer:· "6 + $8000" is the number you would put in.

Jon Williams

38K4 is a Euro-type abbreviation for 38,400; a "standard" baud rate.

One of the things that makes my life easier is conditional compilataion -- especially for things like SERIN/SEROUT that have different parameters based on the module used.· In my standard template I have this section that handles serial parameters; I use it all the time and my serial life is a breeze.

#SELECT $STAMP
  #CASE BS2, BS2E, BS2PE
    T1200       CON     813
    T2400       CON     396
    T4800       CON     188
    T9600       CON     84
    T19K2       CON     32
    TMidi       CON     12
    T38K4       CON     6
  #CASE BS2SX, BS2P
    T1200       CON     2063
    T2400       CON     1021
    T4800       CON     500
    T9600       CON     240
    T19K2       CON     110
    TMidi       CON     60
    T38K4       CON     45
#ENDSELECT
 
SevenBit        CON     $2000
Inverted        CON     $4000
Open            CON     $8000
 
Baud            CON     T9600

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Jon Williams
Applications Engineer, Parallax
Dallas Office

AJI

Thanks I will try that when I get home



The help file for SEROUT does not show 38400 in the chart. That's why I could not figure that out. I did get it needed to be "6" but didnot realise i still needed the "$8000" with it.



now I know what is is for too.

Maybe the PSC·documents could use more exaples or even that chart.

Jon Williams

When one actually reads the help file, you will see that the BS2 family can easily handle 38.4 kBaud -- it's right at the top. The charts are a convenient set of values for "standard" baud rates, but are not by any means limits to what the BASIC Stamp can do. There is also detailed instructions -- in that file -- for calculating any baud rate and mode.

Serial stuff can be tricky, but I assure you that the details are there.

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Jon Williams
Applications Engineer, Parallax
Dallas Office

achilles03

I thought the BS2 could start encountering trouble when you go up to 9600 or so? I remember reading that somewhere in the PBASIC manual... is that only for recieving or something?

Dave

AJI

well it is working and servos movment is much better and smoother

much better than the default.

The only thing I find is that if I turn off the power switch on the BOE I· have to push the rest button. For it to start working again

This might be because I have the baud change statment before the Main loop.

Jon Williams

The when using formatters with SERIN -- like DEC and HEX, etc. -- the baud rate is limited to 9600 baud because the BASIC Stamp has to work in between received bytes. When doing straight (no formatting or flow control) SERIN or SEROUT you can get up to about 50 kBaud.

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Jon Williams
Applications Engineer, Parallax
Dallas Office

achilles03

So could the following command could be transmitted/recieved reliably at 36.4 kbps with the BS2?

SERIN DATAPIN,N36400,[noparse][[/noparse]WAIT("@"),SKIP 3, STR GPSD\4, SKIP 5, STR GPSA\4]

Thanks for the info,
Dave

Jon Williams

No. WAIT, SKIP, STR -- all those take work in between received bytes, and as I pointed out above there is just no time for the BASIC Stamp to do this work at rates above 9600.

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Jon Williams
Applications Engineer, Parallax
Dallas Office