Welcome to EDAboard.com

Welcome to our site! EDAboard.com is an international Electronic Discussion Forum focused on EDA software, circuits, schematics, books, theory, papers, asic, pld, 8051, DSP, Network, RF, Analog Design, PCB, Service Manuals... and a whole lot more! To participate you need to register. Registration is free. Click here to register now.

Register Log in

in MT8870 DTMF decoder?

Status
Not open for further replies.

mai fouad

Junior Member level 1
Joined
Sep 26, 2012
Messages
18
Helped
0
Reputation
0
Reaction score
0
Trophy points
1,281
Activity points
1,393
please i did not understand how the output std is working .and how to find the dial pulse duration so that i can take the output when only there is new output and not duplicate the output or skip one value of the output!!!
 

tpetar

Advanced Member level 5
Joined
Sep 27, 2010
Messages
6,427
Helped
1,712
Reputation
3,454
Reaction score
1,677
Trophy points
1,393
Location
Pancevo-Belgrade, Serbia
Activity points
37,376
Did you check datasheet?

StD
Delayed Steering (Output). Presents a logic high when a received tone-pair has been registered and the output latch updated, returns to logic low when the voltage on St/GT falls below Vtst.

EsT
Early Steering (Output). Presents a logic high once the digital algorithm has detected a valid tone pair (signal condition). Any momentary loss of signal conditionwill cause ESt to return to a logic low.

St-Gt
Steering Input/Guard time (Output) Bidirectional. A voltage greater than Vtst detected at St causes the device to register the detected tone pair and update the output latch. A voltage less than V
TSt frees the device to accept a new tone pair. The GT output acts to reset the external steering time-constant, its state is a function of ESt and the voltage on St.

TOE
Three State Output Enable (Input). Logic high enables the outputs Q1-Q4. This pin is pulled up internally.

Q1-Q4
Three State Data (Output). When enabled by TOE, provide the code corresponding to the last valid tone-pair received (see Table 1). When TOE is logic low, the data outputs are high impedance.

http://hackedgadgets.com/wp-content/uploads/2010/01/mt8870_dtmf_decoder_datasheet.pdf

DTMF Decoder Board
http://www.razorconcepts.net/dtmf.html
 

Status
Not open for further replies.
Toggle Sidebar

Part and Inventory Search

Welcome to EDABoard.com

Sponsor

Top