Reading characters with scanf or getchar in ccs console

Rene Wittmann

Other Parts Discussed in Thread: SYSBIOS

Hello,

I've noticed that getchar() waits for user input in ccs console, but the assigned variable (c = getchar()) does not get the value read, but always 0.

I've seen this problem with the mcspi example of pspdrivers_02_20_01_00 where a 'y' or 'Y' is expected to continue. So I set up a new test project where my observation was the folowing: as soon as I use a module in my .cfg file (with xdc.useModule), the result is the one described above.

If I do not write any xdc.useModule statement in my .cfg file, I can read characters from console with getchar().

Is there an explanation for that? My setup is the following:

XDCTools 3.22.3.41

BIOS 6.32.3.43

IPC 1.23.4.36

CCS 5.1 M7

TI814x either on EVM or custom board (behaviour is the same)

I have attached my sampe project for reference

2475.MyGetChar.zip

Any help would be appreciated.

Thanks and best regards,

Rene

over 13 years ago

0 Alan DeMars over 13 years ago

TI__Mastermind 30830 points

Rene,

I was not able to open the posted .zip file. Winzip is asking for a password.

Alan

0 Rene Wittmann over 13 years ago in reply to Alan DeMars

Intellectual 390 points

Hi Alan,

Sorry, you're right. Password is "password".

My assumption is currently that is due to ccs 5.1 M7. Could this be?

Best regards,

Rene

0 Alan DeMars over 13 years ago in reply to Rene Wittmann

TI__Mastermind 30830 points

Rene,

I looked into this and was not able to reproduce your results.

However, I'd like you to try increasing the 'C' runtime stack size just in case it is overflowing into data structures used by the CIO mechanism within the printf(), getchar(), or fflush() functions.

Please add the following to your config script and see if it changes the behavior:

Program.stack = 16384;

Alan

0 Rene Wittmann over 13 years ago in reply to Alan DeMars

Intellectual 390 points

Hi Alan,

This does not change anything. Please find attached my binary. Can you please check the binary? What version of CCS are you using?

2570.MyGetChar_bin.zip

For me the binary reads in the first character and afterwards prints out the first character.

(If I do a print out before, no char gets read at all).

Regards,
Rene

0 Alan DeMars over 13 years ago in reply to Rene Wittmann

TI__Mastermind 30830 points

Loading your binary into my evmTI8148 board I get the following output:

a
[CortexA8] c=a
b
[CortexA8] c=b
c
[CortexA8] c=c
d
[CortexA8] c=d
e
[CortexA8] c=e
f
[CortexA8] c=f

I suspect that your emulation driver may be out of date and that its having a problem with the A8 cache.

Try adding the following to your config script to disable the A8 caches and see if the problem clears up:

var Cache = xdc.useModule('ti.sysbios.family.arm.a8.Cache');

Cache.enableCache = false;

Alan

0 Alan DeMars over 13 years ago in reply to Alan DeMars

TI__Mastermind 30830 points

There was a cache-related CIO problem with the xds560 emulation driver used for ARM cores in earlier builds of CCS 5.

I suspect your M7 build had the problem.

Try upgrading to the current release of CCS 5.1 available here:

http://processors.wiki.ti.com/index.php/Download_CCS

Alan

0 Rene Wittmann over 13 years ago in reply to Alan DeMars

Intellectual 390 points

Hi Alan,

Sorry for the late reply, but I could not test with M9 release before.

You are correct that it was a problem with M7 build.

Thanks,
René

Processors

Processors forum

Reading characters with scanf or getchar in ccs console