Uart Rx Byte to Variable

[Ferla]

Hello
I have a simple question and I kindly ask for help.
In a loop cycle, I receive a sequence of bytes via Uart. 192168, how do I make 192 a variable and 168 another variable?
Surely it is a trivial question but I can not find the optimal solution.
Ferla

[mnf]

Hi Ferla,

What exactly are you attempting here - are you receiving bytes (ie 192 then 168) or a string of characters = "192168"

Could you receive them into an array

values[0] = Uart1::ReceiveChar(timeout) (or x = ReceiveChar, y = ReceiveChar
...
values[n] = Uart1::ReceiveChar(timeout)

or use a circular buffer?

PutByte(Uart1::ReceiveChar(timeout))

If the data received is a string - then you would need to parse them into the variables - in this case each variable value would have to be a fixed length (say 3 bytes) or use a delimiter (eg ',')

Martin

PS - how goes the project with the LEDs?

[Ferla]

Hi Martin
Very simple.The EB023 module has the possibility of being able to replace the IP address after being initialized, so I wanted through string UART to associate 4 groups for 3 string characters in 4 variables. I receive the string and with a loop I read every single character as byte as long as the string is long.

Example:
StringRx = "192168123213"
VariablileIP0 = 192
VariabileIP1 = 168
VariabileIP2 = 123
VariabileIP3 = 213

I do not understand how to combine these bytes into one single variable.

Thanks!!

[mnf]

Hi Ferla,

Not sure what you mean by that - but here is a simple program that splits the input string into 4 values (I would recommend using an array for these) then rebuilds them into an ip address string (including the '.'s)

Hope this helps....

ip.fcfx

(11.92 KiB) Downloaded 279 times

Martin

[Ferla]

Hi Martin
your example is close to what I wanted, even if it needs changes and adaptations,
because the IP address could also be expressed in decimals like eg. 10.11.12.13 and not always in centesimals 192.168 etc, I know the calculation mul = 100 can not always be good.You will find many variables, do not worry, I did a lot of tests.
If you look at the attachment you will see.
You will also find "[" and "]" which I entered as a check and start and end reception
If you have other suggestions I'm here.
Greetings
Ferla

[mnf]

Hi Ferla,

Using mul = 100 will give you leading 0s in the output ip address - 010.011....

If you don't like this it is easy to change:

Code: Select all

if (ip[i] >= mul) & (mul > 1)

Needs to be added to check in the conversion back to a string... Note that you need to check that mul is not 1 otherwise an value of 0 won't work....

This doesn't help with the input value - you would need a separator otherwise
19216 could be 19.216 or 192.16 - so passing 192016 removes the ambiguity..

Why not pass in the ip address as "192.168.1.254" ?

Martin

[Ferla]

Hi Martin
your suggestion to use the separator have already been considered and I will make this change.
I can use all the bytes received to convert them to string., so I can use your example.
Thanks Ferla

[Ferla]

Martin rereading my last message maybe I expressed my request badly. I wanted to ask you how do I merge all the read bytes and turn them into a string?

[mnf]

Hi Ferla,

It's pretty easy to do:

in pseudocode:

Code: Select all

data is string[20]                  // Using a string (it's an array of char!) of suitable size.
index = 0
loop
  data[index] = ReadByte()   // Get a byte from input source
  index = index + 1               // Advance to next position in string
until data buffer full or input ended.  // i.e. if Index = 19 (for a string size 20)- leave space for a string terminator
data[index] = 0 		  // Stick a 0 on end of string so string handling code works ok

Depending on the input technique - it might also be as straightforward to parse the input stream directly (for example from a circular buffer - if we know that it won't be updated whilst we are working) - might also be appropriate if memory is scarce.

Martin

[Ferla]

Thanks a lot Martin.
My project continues...
Ferla

[Ferla]

Hi Martin,
after taking the run-up I stumbled .. I have problems with the separator. If I insert the following string "10.11.12.10" I should check the separator in order to have a correct control as for your advice and if you enter the digits centesimal, decimal or unit es. 10.11.1.1 see the simulation ip variable {10,56,11,56,12,56,10} . it is know correct to change from ip [4] to ip [7] considering the separators "." ?
I always use your example.

[mnf]

Hi Ferla,

You need a slightly different approach if using a separator... I'll post you a sample this evening...

Martin

[Ferla]

Thank you much Martin,
you're always a great help ...people like you must be rewarded

[mnf]

Okay - this parses an input ip address in the format a.b.c.d (ie 112.1.22.122)

- note that the ip address should be in the correct format (ie 4 values 0..255) and NO allowance is made for variations (for example spaces, extra '.'s, missing values - allowing for every possibility makes the code much more complicated !!! ) Note also that your input string must have a terminating nul \0 (actually any non digit character would do) - you did remember to add a \0 to then end of your input string ?

ip.JPG (27.99 KiB) Viewed 10581 times

The first 'half' does the hard work - the second half just reflects what we calculated to the UART (to check it works!)

To save the typing.

ip.fcfx

(11 KiB) Downloaded 148 times

Hope it helps...


Martin

[Ferla]

Hi Martin
I thank you very much, thanks to your examples I managed to keep going.
Now I have to try everything on the hardware, I hope it works like a simulation.
Greetings see you soon.
Ferla

[mnf]

Good luck - let us know how you get on!

Martin

[Ferla]

Hi Martin
I just can not find the way to pull out the 4 variables from the string.
The received bytes turn them into a string as you want, then I use your last ip.fcfx project and something happens to them that I can not understand. For test I use an LCD display that allows me to check what happens at the end and I realize that I can not turn the string into 4 variables because they are not shown on the display.
Thanks
Ferla

[mnf]

Hi Ferla,

Can you post your current code?

Martin

[Ferla]

Thanks, Martin
the project is composed of the first part where I transform the received bytes into string array,afterwards I visualize if all the string has been correctly received (only for test purpose then inhibited), another step and try to manipulate the string by visualizing the blocks on the display (always for test then inhibited) ,then I get to the point of using your project by entering what has been received,I do not tell you how many proof I did because I lost my bill ... ,in truth and from April 27 (release of your project) I try and try again and again and again......
Before asking for help, I try to try and try it again.
Sometimes I have to admit that some gaps are holding me back

Ferla

[mnf]

Hi Ferla,

Took a quick look at your code and (my Italian is no where near as good as your English) think I've spotted a problem:

In Ass_IP

ass_ip.png

(19.48 KiB) Downloaded 3745 times

Just before you attempt to decode StringIP - you set it to "" (empty string)

This will surely stop things working as you expect!

Another possible problem - is the ip string guaranteed to be all in one block read in (you decrement SIZE to 0 but don't check if a closing ']' has been received - and if it is (assuming the ip is all read) you need to add a terminator (\0) to StringIP.

Martin

[Ferla]

Hi Martin,
I'm happy to hear from you.
When you talk about a terminator (\0), do I have to add it in the flowcode or when I send the string via UDP?
I turned it on to try your suggestion

[mnf]

Adding the calculation macro

Code: Select all

StringIP[index] = '\0' 

Should do the trick (but note my previous comment about all the ip address being within SIZE bytes)

ass_ip2.png

(29.86 KiB) Downloaded 3738 times

Martin

[mnf]

Another possible problem:

If SIZE is greater than the length of StringIP (20) - and after a '[' character is received there is no terminating ']' (due to a corrupted block or some other problem) then Ass_IP will overwrite memory causing a crash or subtle bugs?

Martin

[Ferla]

I'm trying without success ...
Ferla

[mnf]

Try adding some debug statements

So - for example - send StringIP to UART after receiving it.

What have you tried so far (did you implement the above/get rid of the StringIP ="") - any idea where is it going wrong?

Martin