Back to the MT8880 DTMF Chip...initialization nightmares
FlyingFishFinger
Posts: 461
Hi!
Jeez, this is the third time I'm trying to post this...comps kept crashing. So, I finished the hardware side of my circuit, but I have software problems. My board has a weird IO pin scheme, so I cant use the nice nibble approach they use in the NV Column #7. I have to take the number variable apart and write its bits to the pins. My problem is that this code as it is seems to work, but I can change or even remove the initialization lines and it still works (Regardless of what code I use, with or without the "correct" initialization, sometimes I get no tone and sometimes just row or colum tones). My original goal was DTMF decoding, but I guess that won't work until I gte my bits straight. I've been trying to figure it out for a few days, but I can't get it. It may be a dumb error on my part, or it's the lack of understanding of the Stamp's IO variables or the chip's set-up routine.
Oh - I tried to keep pin 5 low all the time...it's connected to ESt on the CM8880 for Detection purposed...it's an input to the Stamp, so I don't know what setting it high would do.
I also keep pins 0,1 and 2 low since they drive a H-Bridge and a serial LCD.
Here is the NV Column #7:
http://www.parallax.com/html_pages/downloads/nvcolumns/Nuts_Volts_Download_V1.asp
Here's a Datasheet for the Chip:
http://assets.zarlink.com/DS/zarlink_MT8880C_SEP_05.pdf
Thanks...pardon the wordiness
Rafael
Post Edited (flyingfishfinger) : 6/27/2006 2:05:21 AM GMT
Jeez, this is the third time I'm trying to post this...comps kept crashing. So, I finished the hardware side of my circuit, but I have software problems. My board has a weird IO pin scheme, so I cant use the nice nibble approach they use in the NV Column #7. I have to take the number variable apart and write its bits to the pins. My problem is that this code as it is seems to work, but I can change or even remove the initialization lines and it still works (Regardless of what code I use, with or without the "correct" initialization, sometimes I get no tone and sometimes just row or colum tones). My original goal was DTMF decoding, but I guess that won't work until I gte my bits straight. I've been trying to figure it out for a few days, but I can't get it. It may be a dumb error on my part, or it's the lack of understanding of the Stamp's IO variables or the chip's set-up routine.
Oh - I tried to keep pin 5 low all the time...it's connected to ESt on the CM8880 for Detection purposed...it's an input to the Stamp, so I don't know what setting it high would do.
I also keep pins 0,1 and 2 low since they drive a H-Bridge and a serial LCD.
Here is the NV Column #7:
http://www.parallax.com/html_pages/downloads/nvcolumns/Nuts_Volts_Download_V1.asp
Here's a Datasheet for the Chip:
http://assets.zarlink.com/DS/zarlink_MT8880C_SEP_05.pdf
Thanks...pardon the wordiness
Rafael
Post Edited (flyingfishfinger) : 6/27/2006 2:05:21 AM GMT
Comments
What development board are you using for the BS-2 application?
Regards,
Bruce Bates
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Rafael
I think I got my bits straight. The Chip now listens to me. Turns out it WAS a dumb mistake - I went back and checked what exactly the demo program for the BS1 from the Nuts and Volts Column does at bit level. I found that I had forgotten to set the Register select pin low after my initialization - so the Chip thought all the data I was sending was going to the control registers.
The above code was overly complicated as usual
Thanks for looking anyway
Rafael
I want to use the ESt pin for tone detection. When I attach a LED to the pin, it lights up when there's a tone and my meter shows 5V. When I attach it to the Stamp pin, all it ever sees is a 0. When I attach the Stamp pin to +5V, it shows a 1 like it should. Could the Stamp pin be sinking more current than the Chip can supply? It can't be more than a LED, can it?
Thanks
Rafael
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·
Steve
"Inside each and every one of us is our one, true authentic swing. Something we was born with. Something that's ours and ours alone. Something that can't be learned... something that's got to be remembered."
Rafael
Rafael
An earphone to the TONE input??· I know that you can use those old in-ear sorts as a really crummy microphone, but...· The tone input should be capacitively (AC) coupled to the "source".
ESt -- is it to confirm a tone generation or a tone reception, or both, depending?
Post Edited (PJ Allen) : 6/29/2006 2:30:04 AM GMT
Rafael
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·
Steve
"Inside each and every one of us is our one, true authentic swing. Something we was born with. Something that's ours and ours alone. Something that can't be learned... something that's got to be remembered."
Rafael
PS: How much current does it take to drive a Stamp pin high? I just realized that the ESt pin can only source -3.0 mA...(but why negative?)
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You've got to play the game.
You can't win.
You can't break even, except on a very cold day.
It doesn't get that cold.
~Laws of Thermodynamics~
Post Edited (FlyingFishFinger) : 6/29/2006 9:00:29 PM GMT
Is it O.C.?·
How does it perform if you connect ESt to +5 through a 47K-100K resistor (but not connected to a STAMP pin)?
Rafael
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You've got to play the game.
You can't win.
You can't break even, except on a very cold day.
It doesn't get that cold.
~Laws of Thermodynamics~
▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
You've got to play the game.
You can't win.
You can't break even, except on a very cold day.
It doesn't get that cold.
~Laws of Thermodynamics~
Thanks for the help
Rafael
▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
You've got to play the game.
You can't win.
You can't break even, except on a very cold day.
It doesn't get that cold.
~Laws of Thermodynamics~