I'd like to help you out, but I have neither PIC basic nor a MT8888 to try it out on. I've simply read the datasheet and tried to point you in the right direction. Anything I write would be pseudo code which you'd have to rewrite for it to work on your compiler. Here are some links that may help:
Home security system
It looks like the CM8888 is the same as the MT8888:
Design and Implementation of DTMF Detector - Scientific, embedded, biomedical, electronics contents.
Inside every little problem, is a big problem trying to get out.
Hi Kchriste,
I am waiting for a shipment of 6 new MT8888's before I continue. I have tried a bit to get this one to work but I think I may have fried it.
Don
Hi KChriste, Are you still around?
I was wondering if you or someone could look at this code and see where I am going wrong. I realize you aren't PicBasic savvy but it is kind of straight forward. It still doesn't seem to work.
Thanks, Don
Code:OSCCON = $60 'Set up internal oscillator CS var portb.4 'Enable or disable MT8888 tied to ground RD var portb.5 'Read Microprocessor input WR var portb.6 'Write Microprocessor input RS var portb.7 'Register Select TRISB = %00000000 'Set portb to output Init var byte Control var byte Dtmf var byte Status var byte w var byte X var byte y var byte z var byte data @1,%11000000,%10100000,%10101000,%10100000,%10101101,%10100000,%00001000,%00001110,%00000001,%00001110,%00000011,%00001110,%00000110 'Data starting at position #1 Gosub Initialization gosub SetupControlRegister gosub WriteTransmitRegister Initialization: Gosub ReadStatusRegister for w = 2 to 4 read w, Init 'Read data statement starting at location #2 and put in Init Init = Init & $0F 'Mask off upper 4 bits with Logical AND portb = Init | %11100000 'Set upper 3 bits with Logical OR and send to portb pause 10 'Wait 1 millisecond (may not be needed) low WR 'Take portb pin 6 low pause 10 'Wait 1 millisecond (may not be needed) high WR 'take portb pin 6 high pause 10 Next w Return ReadstatusRegister: read 1, Status 'Read data statement starting at location #1 and put in Status Status = Status & $0F 'Mask off upper 4 bits with Logical AND portb = Status | %11100000 'Set upper 3 bits with Logical OR and send to portb pause 10 'Wait 1 millisecond (may not be needed) low RD 'Take portb pin 5 low pause 10 'Wait 1 millisecond (may not be needed) high RD 'take portb pin 5 high pause 10 Return SetupControlRegister: for x = 5 to 6 read x, Control 'Read data statement starting at location #6 and put in Control Control = Control & $0F 'Mask off upper 4 bits with Logical AND portb = Control | %11100000 'Set upper 3 bits with Logical OR and send to portb pause 10 'Wait 1 millisecond (may not be needed) low WR 'Take portb pin 6 low pause 10 'Wait 1 millisecond (may not be needed) high WR 'take portb pin 6 high pause 10 Next X Return WriteTransmitRegister: for y = 7 to 13 read y, Dtmf 'Read data statement starting at location #9 and put in Dtmf Dtmf = Dtmf & $0F 'Mask off upper 4 bits with Logical AND portb = Dtmf | %11100000 'Set upper 3 bits with Logical OR and send to portb pause 10 'Wait 1 millisecond (may not be needed) high RD 'Take portb pin 5 high pause 10 'Wait 1 millisecond (may not be needed) low RD 'take portb pin 5 low pause 10 Next y Return End
Last edited by dbachman; 19th January 2009 at 11:09 PM.
In your Initialization routine, you only do 3 writes to the control registers. The Data sheet shows 4 writes with the first two being duplicated. Since the upper 4bits are masked off anyway, you could fix that by changing for w = 2 to 4 to for w = 1 to 4
There is also supposed to be a read from the status register at the beginning of the Initialization routine and at the end. You only have it at the beginning.
I have only glanced briefly at the rest of the code.
Last edited by kchriste; 20th January 2009 at 12:05 AM. Reason: for w = 2 to 4
Inside every little problem, is a big problem trying to get out.
The Apps engineer a Zarlink said the Write was a redundant one. Have a look at this code using an MT8880 (which is almost the same). It's datasheet is very similar. It doesn't even initialize it even tho the datasheet says it should. Also this attachment. I am not good at Assembly.
Thanks, Don
Code:' Listing 1. Stamp-Based Autodialer ' Program: DIAL.SRC (Sends a string of DTMF tones via the 8880) ' This program demonstrates how to use the CM8880 as a DTMF tone ' generator. All that's required is to initialize the 8880 properly, ' then write the number of the desired DTMF tone to the 8880's ' 4-bit bus. ' The symbols below are the pin numbers to which the 8880's ' control inputs are connected, and one variable used to read ' digits out of a lookup table. SYMBOL RS_p = 4 ' Register-select pin (0=data). SYMBOL RW_p = 5 ' Read/Write pin (0=write). SYMBOL CS_p = 6 ' Chip-select pin (0=active). SYMBOL digit = b2 ' Index of digits to dial. ' This code initializes the 8880 for dialing by writing to its ' internal control registers CRA and CRB. The write occurs when ' CS (pin 6) is taken low, then returned high. See the accompanying ' article for an explanation of the 8880's registers. let pins = 255 ' All pins high to deselect 8880. let dirs = 255 ' Set up to write to 8880 (all outputs). let pins = %00011011 ' Set up register A, next write to register B. high CS_p let pins = %00010000 ' Clear register B; ready to send DTMF. high CS_p Stamp Applications no. 7, September 1995 7 ' This for/next loop dials the seven digits of my fax number. For ' simplicity, it writes the digit to be dialed directly to the output ' pins. Since valid digits are between 0 and 15, this also takes RS, ' RW, and CS low--perfect for writing data to the 8880. To complete ' the write, the CS line is returned high. The initialization above ' sets the 8880 for tone bursts of 200 ms duration, so we pause ' 250 ms between digits. Note: in the DTMF code as used by the phone ' system, zero is represented by ten (1010 binary) not 0. That's why ' the phone number 459-0623 is coded 4,5,9,10,6,2,3. for digit = 0 to 6 lookup digit,(4,5,9,10,6,2,3),pins ' Write current digit to pins. high CS_p ' Done with write. pause 250 ' Wait to dial next digit. next digit end ' Listing 2.
Well, you could try the example code you posted above. Looks like you'd have to mod your hardware a bit though. I noticed that the author is setting up the RW, RS, CS and data bits first and then just toggling CS high again to finish the write cycle. Might be worth giving it a try as the code has been tested so if it doesn't work then it must be a hardware issue. Might narrow things down for you.
Inside every little problem, is a big problem trying to get out.
I did give it a try but I am still waiting for the new MT8888's to come in the mail. They keep pushing the ship date out. I might be fighting a fried chip.
Don
hi sir
is your module working sir?
i have some doubts
1}in data sheet it is specified that for 28pin, portb register are disable , but ur using portb only does it work?
hope ull reply
I have never been able to get it to work properly>>>>>>Originally Posted by meghana.mallikarjun
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