TheBackShed.com

Forum Index : Microcontroller and PC projects : I2C Problem - Lines being split

Author

Message

Bizzie
Senior Member

Joined: 06/07/2014
Location: Australia
Posts: 192

Posted: 02:15pm 20 Oct 2015

Copy link to clipboard

Print this post

Hi All,

Why is there a problem in this simple test code?

Here is the code for the "Tramsmit" end :-

> list

I2C Open 100,100

Do
A = A + 1
InBuff$ = ">" + Str$(A) + ",11,12,13,14,15,16<"
I2C Write &H26,0,Len(inbuff$),InBuff$
Print InBuff$
Pause 1500
Loop

> ? mm.ver
4.05
> run
>1,11,12,13,14,15,16<
>2,11,12,13,14,15,16<
>3,11,12,13,14,15,16<
>4,11,12,13,14,15,16<
>5,11,12,13,14,15,16<
>6,11,12,13,14,15,16<
>

And for the receive :-

> list
' Bar graph display.

' Data from I2C

I2C SLAVE Open &H26,0,0,WriteD,ReadD

Do
WatchDog 1000
Loop

Sub BarGraf

End Sub

Sub ReadD
I2C Slave Read 70,InBuff$,Recd
Print Recd;"- ";InBuff$
BarGraf
End Sub

Sub WriteD

End Sub
> ? mm.ver
4.07
> run
2- >1
6- ,11,12
13- ,13,14,15,16<
2- >2
5- ,11,1
14- 2,13,14,15,16<
2- >3
6- ,11,12
13- ,13,14,15,16<
2- >4
5- ,11,1
14- 2,13,14,15,16<
2- >5
6- ,11,12
13- ,13,14,15,16<
2- >6
6- ,11,12
13- ,13,14,15,16<
2- >7
5- ,11,1
14- 2,13,14,15,16<
2- >8
6- ,11,12
13- ,13,14,15,16<
>

Note MM version info ie Maximite on transmit side and MicroMite on receive

Expected output :-
21- >8 ,11,12,13,14,15,16<

Anyone any ideas?

Rob

Rob White

TassyJim

Guru

Joined: 07/08/2011
Location: Australia
Posts: 6283

Posted: 03:37pm 20 Oct 2015

Copy link to clipboard

Print this post

You appear to be suffering from the usual problem with serial comms.
The interrupt occurs as soon as the first character is received but it takes time for the rest of the message to arrive.
A simple 'PAUSE 400' at the beginning of your readD sub should solve the problem.
You may ahve to adjust the delay time to suit your data length.
Keep reducing the time until characters are lost the add a suitable time 'to be sure'.
The alternative is to store the incoming data into a buffer until you get to an end of data condition (character count or flag character etc).

Jim

Edit: It takes about 100uS for a character at 100k so if you are looking for up to 70 characters, try a delay of 10mS

Edited by TassyJim 2015-10-22

VK7JH
MMedit

Bizzie
Senior Member

Joined: 06/07/2014
Location: Australia
Posts: 192

Posted: 05:39pm 20 Oct 2015

Copy link to clipboard

Print this post

Thanks Jim,

As always simple when explained to you!

Regards

Rob

Rob White

Print this page

To reply to this topic, you need to log in.