AVR-Chat

I made a program in asm that kinda works. the only problem is when my 
mega16 xmits to hyperterminal I get weird symbols. I am working with 
4Mhz 4800 baud. the letters in sram are in hex format. But the 
symbols in HT look like they are from the extended ascII table. My 
baud rate is set at 0x51. Has anyone else have a simliar problem?

Brian


..........
main:
	ldi	ZH,high(message*2)	; Load high part of byte 
address into ZH
	ldi	ZL,low(message*2)	; Load low part of byte 
address into ZL
	clr	r0					;

menu:
	lpm						; Load byte 
from program memory into r0
	nop						;
	nop						;
	tst	r0					; Check if I 
reached the end of the message
	breq	run				; If so, continue
	mov treg, r0			;xmit message
	rcall txcomp			;
	adiw	ZL,1			; Increase Z registers
	rcall menu				;
.........
message:
	.db     $50,$72		; P ,r
	.db     $65,$73         ; e ,s
	.db     $73,$20         ; s ,SP
	.db     $61,$6E         ; a ,n 
	.db     $79,$20         ; y ,SP
	.db     $6B,$65         ; k ,e 
	.db     $79,$20         ; y ,SP
	.db     $74,$6F         ; t ,o 
	.db     $20,$63         ; SP,c
	.db     $6F,$6E         ; o ,n
	.db     $74,$69         ; t ,i 
	.db     $6E,$75         ; n ,u
	.db     $65,$0A         ; e ,LF
	.db     $0A,$0D         ; LF,CR
	.db     $00,$00         ; END

--- In AVR-Chat@yahoogroups.com, "David VanHorn" <microbrix@...> wrote:
>
> What is the call to txcomp?
> 
> Normally, I poll the tx tg empty flag before sending a char
>
txcomp: sbis UCSRA,UDRE      	;poll to check end of transmission
        rjmp txcomp		;
        out UDR, treg		;
        ret			;

Everything seems to work except the characture translation.

Brian

--- In AVR-Chat@yahoogroups.com, "Ranjit Puri" <ranjit.puri@...> wrote:
>
> Are you using an external crystal or internal RC Osc ? In case you 
are using
> RC to derive clock you might want to shift the value in UBRR +/- 2.
> 
I have tried +/-2, 4, and 5. It changes the charactures but not 
readable. 

If it helps...
In studio4 my int clock is read as 3.686Khz.

Brian

Are you using an external crystal or internal RC Osc ? In case you are using
RC to derive clock you might want to shift the value in UBRR +/- 2.

On Sat, Apr 5, 2008 at 8:26 PM, Brian <blue_eagle74@yahoo.com> wrote:

>   I made a program in asm that kinda works. the only problem is when my
> mega16 xmits to hyperterminal I get weird symbols. I am working with
> 4Mhz 4800 baud. the letters in sram are in hex format. But the
> symbols in HT look like they are from the extended ascII table. My
> baud rate is set at 0x51. Has anyone else have a simliar problem?
>
> Brian
>
> ..........
> main:
> ldi ZH,high(message*2) ; Load high part of byte
> address into ZH
> ldi ZL,low(message*2) ; Load low part of byte
> address into ZL
> clr r0 ;
>
> menu:
> lpm ; Load byte
> from program memory into r0
> nop ;
> nop ;
> tst r0 ; Check if I
> reached the end of the message
> breq run ; If so, continue
> mov treg, r0 ;xmit message
> rcall txcomp ;
> adiw ZL,1 ; Increase Z registers
> rcall menu ;
> .........
> message:
> .db $50,$72 ; P ,r
> .db $65,$73 ; e ,s
> .db $73,$20 ; s ,SP
> .db $61,$6E ; a ,n
> .db $79,$20 ; y ,SP
> .db $6B,$65 ; k ,e
> .db $79,$20 ; y ,SP
> .db $74,$6F ; t ,o
> .db $20,$63 ; SP,c
> .db $6F,$6E ; o ,n
> .db $74,$69 ; t ,i
> .db $6E,$75 ; n ,u
> .db $65,$0A ; e ,LF
> .db $0A,$0D ; LF,CR
> .db $00,$00 ; END
>
>  
>



-- 
Ranjit


[Non-text portions of this message have been removed]

What is the call to txcomp?

Normally, I poll the tx tg empty flag before sending a char

--- In AVR-Chat@yahoogroups.com, John Samperi <samperi@...> wrote:
>
> At 12:49 PM 6/04/2008, you wrote:
> >In studio4 my int clock is read as 3.686Khz.
> 
> ?? You DID say 4 MHz before, which is it? Are you using
> a crystal for the clock? If not you can pretty much
> forget about decent and stable comms.
> 
> How is the USART initialized?
> 
> Are you trying to disguise you message?
> 
> What's wrong with:
> message:
> .db "Press space key to continue", $0A,$0A,$0D,$00
> 
> Unless you are using a very old chip you may also want to try:
> lpm rx,z+
> 
> where rx is any unused register.
> 
> Regards
> 
> John Samperi
I am using the atmega16l. I programmed the fuse bits for internal 
4Mhz. When I read the stk500 osc in studio4 it says 3.686Mhz. I have 
tried various baud rate setting +/- a couple from $51 to UBRRL.

As far as I know, when using lpm the result is stored in r0. I am 
limited in info right now, just learning.

When I make a program to echo what I type it works and I see what I 
type in HT. But trying to pull data from ram and send it to HT it 
doesnt work. I was thinking that sending a hex character to HT it 
would show in ascII format so I can read it.

Brian

At 12:49 PM 6/04/2008, you wrote:
>In studio4 my int clock is read as 3.686Khz.

?? You DID say 4 MHz before, which is it? Are you using
a crystal for the clock? If not you can pretty much
forget about decent and stable comms.

How is the USART initialized?

Are you trying to disguise you message?

What's wrong with:
message:
.db "Press space key to continue", $0A,$0A,$0D,$00

Unless you are using a very old chip you may also want to try:
lpm rx,z+

where rx is any unused register.

Regards

John Samperi

********************************************************
Ampertronics Pty. Ltd.
11 Brokenwood Place Baulkham Hills, NSW 2153 AUSTRALIA
Tel. (02) 9674-6495       Fax (02) 9674-8745
Email: john@ampertronics.com.au
Website  http://www.ampertronics.com.au
*Electronic Design * Custom Products * Contract Assembly
********************************************************

At 01:51 PM 6/04/2008, you wrote:
>I am using the atmega16l. I programmed the fuse bits for internal
>4Mhz. When I read the stk500 osc in studio4 it says 3.686Mhz.

Ok things are a bit clearer now. With the STK500 you have to put the
OSCSEL jumper correctly. You can have the internal clock, the external
crystal clock or the STK500 generated clock which is what you are reading
with Studio. Read up on the OSCSEL to see how to set this correctly,
it's in the Studio help file as well as the docs you got with the STK.
The one in Studio is the latest.

>I have
>tried various baud rate setting +/- a couple from $51 to UBRRL.

Get the above correct first.

>As far as I know, when using lpm the result is stored in r0.

Correct, so it will work as you have it, however the chip will also
support the more advanced version I showed you ant you save a bit of
code. Not important at the moment

>But trying to pull data from ram

The program is NOT reading data from ram but from flash with lpm.
Your string is stored in flash, so unless you have a routine to read
it from there and put it into ram you will be reading random rubbish.

HOWEVER if you want to read from ram lpm is not good, you will need to
use lds.


Regards

John Samperi

********************************************************
Ampertronics Pty. Ltd.
11 Brokenwood Place Baulkham Hills, NSW 2153 AUSTRALIA
Tel. (02) 9674-6495       Fax (02) 9674-8745
Email: john@ampertronics.com.au
Website  http://www.ampertronics.com.au
*Electronic Design * Custom Products * Contract Assembly
********************************************************

--- In AVR-Chat@yahoogroups.com, "Brian" <blue_eagle74@...> wrote:
>
> I made a program in asm that kinda works. the only problem is when my 
> mega16 xmits to hyperterminal I get weird symbols. I am working with 
> 4Mhz 4800 baud. the letters in sram are in hex format. But the 
> symbols in HT look like they are from the extended ascII table. My 
> baud rate is set at 0x51. Has anyone else have a simliar problem?
> 
> Brian
> 
> 
> ..........
> main:
> 	ldi	ZH,high(message*2)	; Load high part of byte 
> address into ZH
> 	ldi	ZL,low(message*2)	; Load low part of byte 
> address into ZL
> 	clr	r0					;
> 
> menu:
> 	lpm						; Load byte 
> from program memory into r0
> 	nop						;
> 	nop						;
> 	tst	r0					; Check if I 
> reached the end of the message
> 	breq	run				; If so, continue
> 	mov treg, r0			;xmit message
> 	rcall txcomp			;
> 	adiw	ZL,1			; Increase Z registers
> 	rcall menu				;


Wouldn't this last instruction be "rjmp menu"?

Mark Jordan

> > menu:
> > 	lpm						; Load byte 
> > from program memory into r0
> > 	nop						;
> > 	nop						;
> > 	tst	r0					; Check if I 
> > reached the end of the message
> > 	breq	run				; If so, continue
> > 	mov treg, r0			;xmit message
> > 	rcall txcomp			;
> > 	adiw	ZL,1			; Increase Z registers
> > 	rcall menu				;
> 
> 
> Wouldn't this last instruction be "rjmp menu"?
> 
> Mark Jordan
>
Yes it should be. I got carried away with my calls.

Brian

The internal oscillator isn't guaranteed to be accurate enough for serial.
It works, but it may not always work. If the baud rate is wrong,
you'll get odd translations.

--- In AVR-Chat@yahoogroups.com, "David VanHorn" <microbrix@...> wrote:
>
> The internal oscillator isn't guaranteed to be accurate enough for 
serial.
> It works, but it may not always work. If the baud rate is wrong,
> you'll get odd translations.
>
Whoo hoo I figured it out (after about 30 hours of trial and error).

The mega16 has 3 buffer levels not 2 (I read this about a dozen times 
in the data sheet but didnt think anything about it). So when figuring 
out baud rate for UBRR you have to use 24 in the calculation not 16.

I kinda understand this but if anybody has more information to clear it 
up would be great.

Thanks,
Brian

--- In AVR-Chat@yahoogroups.com, John Samperi <samperi@...> wrote:
>
> At 08:52 AM 7/04/2008, you wrote:
> >I kinda understand this
> 
> Good for you! I don't know what you are talking about. :-)
> 
> 
> Regards
> 
> John Samperi
> 
In previous post I said I was having problems with comms between the 
mega16 and hyperterminal.
 I was referenceing 
http://www.avrfreaks.net/index.php?
name=PNphpBB2&file=viewtopic&t=45341&highlight=usart
when I was writing my program. that is where I ran into problems. It 
is a general tutorial and not custome to the mega16.

Brian

At 08:52 AM 7/04/2008, you wrote:
>I kinda understand this

Good for you! I don't know what you are talking about. :-)


Regards

John Samperi

********************************************************
Ampertronics Pty. Ltd.
11 Brokenwood Place Baulkham Hills, NSW 2153 AUSTRALIA
Tel. (02) 9674-6495       Fax (02) 9674-8745
Email: john@ampertronics.com.au
Website  http://www.ampertronics.com.au
*Electronic Design * Custom Products * Contract Assembly
********************************************************

>-----Original Message-----
>From: AVR-Chat@yahoogroups.com [mailto:AVR-Chat@yahoogroups.com] On
Behalf Of Brian
>
>The mega16 has 3 buffer levels not 2 (I read this about a dozen times 
>in the data sheet but didnt think anything about it). So when figuring 
>out baud rate for UBRR you have to use 24 in the calculation not 16.
>
>I kinda understand this but if anybody has more information to clear it

>up would be great.

Have a look at the Mega16 datasheet on page 145 and you'll see that
nowhere does it say to use 24 as a UBRR divisor, it's always 16 (or 8
for double speed mode). If you're having to use 24 then either your
clock speed is wrong or you ar esetting the wrong divisor. You stated
that '0x51' is the correct divisor, however it should be a decimal '51'
not hex '51' which is what you are setting.

Brian (another one)

No virus found in this outgoing message.
Checked by AVG. 
Version: 7.5.519 / Virus Database: 269.22.8/1362 - Release Date:
06/04/2008 11:12

> Have a look at the Mega16 datasheet on page 145 and you'll see that
> nowhere does it say to use 24 as a UBRR divisor, it's always 16 (or 
8
> for double speed mode). If you're having to use 24 then either your
> clock speed is wrong or you ar esetting the wrong divisor. You 
stated
> that '0x51' is the correct divisor, however it should be a 
decimal '51'
> not hex '51' which is what you are setting.
> 
> Brian (another one)

I have read the datasheet. I'm not sure why it worked but it does and 
yes I would like to figure it out.

I have uploaded photos for my clock signal for a 2.4576 xtl
http://tech.ph.groups.yahoo.com/group/AVR-Chat/photos/view/ba64?b=1

and the data stream set at 9600 baud.
http://tech.ph.groups.yahoo.com/group/AVR-Chat/photos/view/ba64?b=2

Is there a prescaler for the system clock? Not sure what to look at 
next to figure it out.

Brian

Could we be having a "Mars Rover" problem?  0x16 = 22 decimal (close to 
24), could this be a hex vs. decimal thing?

Just a blind speculation,
DLC

Brian wrote:
>> Have a look at the Mega16 datasheet on page 145 and you'll see that
>> nowhere does it say to use 24 as a UBRR divisor, it's always 16 (or 
> 8
>> for double speed mode). If you're having to use 24 then either your
>> clock speed is wrong or you ar esetting the wrong divisor. You 
> stated
>> that '0x51' is the correct divisor, however it should be a 
> decimal '51'
>> not hex '51' which is what you are setting.
>>
>> Brian (another one)
> 
> I have read the datasheet. I'm not sure why it worked but it does and 
> yes I would like to figure it out.
> 
> I have uploaded photos for my clock signal for a 2.4576 xtl
> http://tech.ph.groups.yahoo.com/group/AVR-Chat/photos/view/ba64?b=1
> 
> and the data stream set at 9600 baud.
> http://tech.ph.groups.yahoo.com/group/AVR-Chat/photos/view/ba64?b=2
> 
> Is there a prescaler for the system clock? Not sure what to look at 
> next to figure it out.
> 
> Brian
> 
> 
> 
> ------------------------------------
> 
> Yahoo! Groups Links
> 
> 
> 

-- 
-------------------------------------------------
Dennis Clark          TTT Enterprises
www.techtoystoday.com
-------------------------------------------------

>> You stated that '0x51' is the correct divisor, however it should be a
decimal '51' not hex '51' which is what you are setting.
>> 

>Not sure what to look at next to figure it out.
>
>Brian

See my comments about '51'.

Brian (the other one)

No virus found in this outgoing message.
Checked by AVG. 
Version: 7.5.519 / Virus Database: 269.22.9/1364 - Release Date:
07/04/2008 18:38

> >> You stated that '0x51' is the correct divisor, however it should 
be a
> decimal '51' not hex '51' which is what you are setting.
> >> 
> 
> >Not sure what to look at next to figure it out.
> >
> >Brian
> 
> See my comments about '51'.
> 
> Brian (the other one)
OK, I am using a 2.45Mhz xtl, verified buy a digital oscope, remove the 
xtl and the chip doesnt work so I should have my fuses right, and baud 
rate of 9600. My UBRR is set at 10 to get good comms. I am using 16 as 
a divisor, the date sheet says to use 12 as UBRR for 2Mhz. Why am I 
needing a lower number for a little highter freq? Is it ok/common for 
this? I am using a USB to serial to the computer and my STK500.

Brian

>  My UBRR is set at 10 to get good comms. I am using 16 as
> >  a divisor, the date sheet says to use 12 as UBRR for 2Mhz.
> 
> Which base are all those numbers in?
> 0x10 <> 10 <> 00000010b
>
Sorry I didnt mention. it is in hex.

	ldi r16, 0x10					;Set baud rate
	ldi r17, 0x00					;2.45M xtl 9600 
baud
	out UBRRH, r17					;
	out UBRRL, r16					;

This works on my computer at home and at work.

Brian

My UBRR is set at 10 to get good comms. I am using 16 as
>  a divisor, the date sheet says to use 12 as UBRR for 2Mhz.

Which base are all those numbers in?
0x10 <> 10 <> 00000010b

> ...and by the way from which data sheet did you get that value from?
> I know you must HAVE double checked the data sheet already....
> 
> Regards
> 
> John Samperi
The problem came from understanding the STK500. I measured the freq it 
was using, nomatter what I set the fuses at it was set at 16Mhz, I was 
thinking 8Mhz which i set it to, that may be why 24 worked, measured 
from the xtl1 pin. I put my own xtl in to make sure it was operating at 
the freq i knew. It now makes sence.

Brian

P.S. If anyone wants to shoot me down or tell me what I do wrong I will 
not get mad just strive to be better and learn more. My goal is to be 
the best so that I can teach others to be better. not to mention AVR's 
are so much fun. I love to see them do what I tell them to do.

At 11:20 AM 9/04/2008, you wrote:
>OK, I am using a 2.45Mhz xtl,

So far we have had:
 >> In studio4 my int clock is read as 3.686Khz.
 >> ?? You DID say 4 MHz before, which is it?

And I guess you did read all of my suggestions from the 6th??



Regards

John Samperi

********************************************************
Ampertronics Pty. Ltd.
11 Brokenwood Place Baulkham Hills, NSW 2153 AUSTRALIA
Tel. (02) 9674-6495       Fax (02) 9674-8745
Email: john@ampertronics.com.au
Website  http://www.ampertronics.com.au
*Electronic Design * Custom Products * Contract Assembly
********************************************************

At 11:33 AM 9/04/2008, you wrote:
>Sorry I didnt mention. it is in hex.
>
>         ldi r16, 0x10                                   ;Set baud rate

...and by the way from which data sheet did you get that value from?
I know you must HAVE double checked the data sheet already....

Regards

John Samperi

********************************************************
Ampertronics Pty. Ltd.
11 Brokenwood Place Baulkham Hills, NSW 2153 AUSTRALIA
Tel. (02) 9674-6495       Fax (02) 9674-8745
Email: john@ampertronics.com.au
Website  http://www.ampertronics.com.au
*Electronic Design * Custom Products * Contract Assembly
********************************************************

--- In AVR-Chat@yahoogroups.com, "Brian" <blue_eagle74@...> wrote:
>
> The problem came from understanding the STK500. I measured the freq 
it 
> was using, nomatter what I set the fuses at it was set at 16Mhz, I 
was 
> thinking 8Mhz which i set it to, that may be why 24 worked, 
measured 
> from the xtl1 pin. I put my own xtl in to make sure it was 
operating at 
> the freq i knew. It now makes sence.

Dear "blue eagle" Brian,

My problem comes from understanding what exactly you are doing and 
what you want to acheive: Does the text above mean that you use an 
external clock source (crystal, resonator, STK500 clock circuitry) 
and try to use the AVR fuses to change the frequency? Or do you use 
the AVR internal RC clock generator and program it for different 
frequencies (then please tell me how you get it to 16MHz!)?

Maybe you stop providing only small puzzle pieces of info and start 
this thread all over again by describing what you want to do, what 
you tried so far and how it failed?

> P.S. If anyone wants to shoot me down or tell me what I do wrong I 
will 
> not get mad just strive to be better and learn more.

Nobody wants to shoot you (- or, well, now that you mention... ;-)), 
but sometimes people (not only you) make it rather difficult to 
understand their problem in order to be able to provide some help.

Hmmm...the highest frequency in my STK500 is 7.37 MHz provided by the
crystal (XC200).

Is this a new design?

 

Ray Hurst

Western Digital

20511 Lake Forest Drive

Lake Forest, CA 92630

949-672-9853

 

 

________________________________

From: AVR-Chat@yahoogroups.com [mailto:AVR-Chat@yahoogroups.com] On Behalf
Of Brian
Sent: Tuesday, April 08, 2008 8:44 PM
To: AVR-Chat@yahoogroups.com
Subject: [AVR-Chat] Re: comms problem

 

> ...and by the way from which data sheet did you get that value from?
> I know you must HAVE double checked the data sheet already....
> 
> Regards
> 
> John Samperi
The problem came from understanding the STK500. I measured the freq it 
was using, nomatter what I set the fuses at it was set at 16Mhz, I was 
thinking 8Mhz which i set it to, that may be why 24 worked, measured 
from the xtl1 pin. I put my own xtl in to make sure it was operating at 
the freq i knew. It now makes sence.

Brian

P.S. If anyone wants to shoot me down or tell me what I do wrong I will 
not get mad just strive to be better and learn more. My goal is to be 
the best so that I can teach others to be better. not to mention AVR's 
are so much fun. I love to see them do what I tell them to do.

 



[Non-text portions of this message have been removed]

Brian,

For a 2.4567 MHz xtal:

            UBRR = (2456700/(16 * 9600)) - 1 = 15

 

Using 16 for UBBR:

            Baud = 2456700/(16 * (UBBR + 1)) = 9031.98

 

%error = (9600 - 9301.98)/9600 * 100% = .06%

 

Having a UBBR of 15 has not error, UBBR of 16 has a .06% error.

This is probably acceptable for single character transfers but I direct you
to page 168 of the ATmega16L data sheet for a discussion on the effect of
the baud error rate on data transfers.

 

Ray

 

 

________________________________

From: AVR-Chat@yahoogroups.com [mailto:AVR-Chat@yahoogroups.com] On Behalf
Of Brian
Sent: Tuesday, April 08, 2008 8:44 PM
To: AVR-Chat@yahoogroups.com
Subject: [AVR-Chat] Re: comms problem

 

> ...and by the way from which data sheet did you get that value from?
> I know you must HAVE double checked the data sheet already....
> 
> Regards
> 
> John Samperi
The problem came from understanding the STK500. I measured the freq it 
was using, nomatter what I set the fuses at it was set at 16Mhz, I was 
thinking 8Mhz which i set it to, that may be why 24 worked, measured 
from the xtl1 pin. I put my own xtl in to make sure it was operating at 
the freq i knew. It now makes sence.

Brian

P.S. If anyone wants to shoot me down or tell me what I do wrong I will 
not get mad just strive to be better and learn more. My goal is to be 
the best so that I can teach others to be better. not to mention AVR's 
are so much fun. I love to see them do what I tell them to do.



[Non-text portions of this message have been removed]

On Wed, Apr 09, 2008 at 09:45:47AM -0700, Raymond Hurst wrote:
> 
> %error = (9600 - 9301.98)/9600 * 100% = .06%

Try again. Error is 3.1%. 2% is the commonly accepted worst case
mismatch.

-- 
David Kelly N4HHE, dkelly@HiWAAY.net
========================================================================
Whom computers would destroy, they must first drive mad.

Thanks for the correction.

Gotta replace that calculator.

Ray Hurst

 

 

________________________________

From: AVR-Chat@yahoogroups.com [mailto:AVR-Chat@yahoogroups.com] On Behalf
Of David Kelly
Sent: Wednesday, April 09, 2008 10:10 AM
To: AVR-Chat@yahoogroups.com
Subject: Re: [AVR-Chat] Re: comms problem

 

On Wed, Apr 09, 2008 at 09:45:47AM -0700, Raymond Hurst wrote:
> 
> %error = (9600 - 9301.98)/9600 * 100% = .06%

Try again. Error is 3.1%. 2% is the commonly accepted worst case
mismatch.

-- 
David Kelly N4HHE, dkelly@HiWAAY.net <mailto:dkelly%40HiWAAY.net> 
========================================================================





[Non-text portions of this message have been removed]