Writing values to SD card

mosquito56 · 2008-03-03 17:50

value:=123445

r := sdfat.popen(string("value.txt"), "w")
   repeat y from 0 to strsize(@value)
     r:=byte[noparse][[/noparse]@value[noparse][[/noparse]y]]
     sdfat.pputc(r)

sdfat.pputc(13)
sdfat.pclose

THis should write 123445 to the card in file "Value" but doesn't. Help?

I tried pwrite(@value,strsize(@value)), no luck.

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Mike Green · 2008-03-03 18:05

What's value? How's it declared? It looks like you might have declared it as a LONG or maybe a BYTE array?
If you declared it as a long, it's a binary number, not a sequence of characters. Take a look at the "dec" routine
in FullDuplexSerial for an example of a routine to write a series of digits for a number. If you did declare it as a
byte array long enough to hold a string, where do you store the value? "value := 123445" won't do it. Lastly,
you're outputting the terminating zero byte to the file. Did you want that?

mosquito56 · 2008-03-03 18:32

Value was declared as long. Changed to byte[noparse][[/noparse]8] and will try again.
The··sdfat.pputc(13) was taken directly from the only write example in sdrw-test. This is the only write example I can find for the sd card. Maybe should be $0D?
·

 repeat 3
         sdfat.pputc("H")
         sdfat.pputc("E")
         sdfat.pputc("x")
         
         
      sdfat.pputc(13)

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······· "What do you mean, it doesn't have any tubes?"
······· "No such thing as a dumb question" unless it's on the internet
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rokicki · 2008-03-03 18:36

Howdy!

Try the following:

value:=string("123445")
r := sdfat.popen(string("value.txt"), "w")
   repeat y from 0 to strsize(value)-1
     r:=byte[noparse][[/noparse]value][noparse][[/noparse]y]
     sdfat.pputc(r)
sdfat.pputc(13)
sdfat.pputc(10)
sdfat.pclose

This is off the top of my head but I think it's right.

Note that to actually write an integer out as ASCII you will need to convert the
integer value to a sequence of byte values that contain the ASCII digits.

[noparse][[/noparse]Edited to not output the trailing zero.]

Post Edited (rokicki) : 3/3/2008 6:54:15 PM GMT

deSilva · 2008-03-03 18:45

You still output the trailing zero, as Mike pointed out! Most likely unwanted...

mosquito56 · 2008-03-03 19:02

Rokici, I think I've found· the problem.
1. Conver number to ascii string··· aka. Dec(value,scaleby)
2. Read the "string" and write the characters. Basically just the reverse of reading the characters.

r:= sdfat.mount(0)
'term.hex(r,2)
x:=0
r := sdfat.popen(string("hobbs.txt"), "r")
'term.hex(r,2) 
mult:=1
 repeat while r=>0
 
   r:= sdfat.pgetc  
  
   if r => ("0") and r =< ("9")
     byte[noparse][[/noparse]@infoin[noparse][[/noparse]x++]]:=r 
     mult:=mult*10
mult:=mult/10   
hobbsvalue:=0
  repeat y from 0 to x-1 
    r:=byte[noparse][[/noparse]@infoin[noparse][[/noparse]y]]
    val:=(r-48)*mult
    hobbsvalue:=hobbsvalue+val
    mult:=mult/10
term.str(string("Read  "))  
term.dec(hobbsvalue)   
sdfat.pclose
'waitcnt(clkfreq*4+cnt)

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······· "What do you mean, it doesn't have any tubes?"
······· "No such thing as a dumb question" unless it's on the internet
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frankwillis · 2012-04-04 19:15

Question:
If I am simply trying to write the variable as a string, how do I declare it?
Can you give me a very simple example that does this with FSRW...

x=200
y = 400

then print x and y to a card as strings on separate lines.

Mike Green · 2012-04-04 20:29

"write the variable as a string" ...

How do you want to write it? The variable's value could be displayed as a decimal number or a hexadecimal number or a binary number or as a 1 to 4 character string or ...

If you want to treat the variable's value as a decimal number, you could use the Numbers object from the Propeller Object Exchange. This has a variety of routines for converting a numeric value to any of several string representations (decimal, hexadecimal, etc.) contained in a buffer internal to the Numbers object. These routines then return the address of the start of the buffer which you pass to the pputs routine in fsrw like this: sdfat.pputs(address)

If you declare OBJ num : "Numbers" then you'd call sdfat.pputs(num.ToStr(x,num#DEC)) or sdfat.pputs(num.ToStr(y,num#DEC))

To get the numbers on separate lines, you'd need to do sdfat.pputs(string(13,10)) to mark the end of each line.

For the above to work, x and y could be constants or they could be any kind of variable or they could be complex expressions. The net result is the same. ToStr expects a numeric value which would always be a signed 32-bit value. A word or byte value would be converted to a 32-bit value.

Writing values to SD card

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