After that there is a call of the subprogramme of service of port of indication. This subprogramme makes consecutive connection of DD.3-DD.11 indicators through P1 port, with simultaneous exposure of a code of the corresponding figure. This code arrives on an entrance of the decoder DD.2 where it will be transformed to codes of the seven-segment indicator, and arrives then on the corresponding entrances of DD.3-DD.1 indicators
In each cycle time for service of port of indication of the dialed number is allowed. Indicators work in the dynamic mode that gives the chance to remove at once some figures of number dialed by the subscriber.
Proceeding from the above description of knots, it is possible to make the schematic diagram of the device (see enc. which and to accept, in total with the program (see enc. as implementation of the specification on a term paper.
If it is hung up, check on pressing of the button "Call" and if it is pressed becomes, the microcontroller generates impulses of zvonkovy frequency the corresponding packs and does it, the tube on the device will not rise yet, or the call button will not be released. These impulses arrive on the inverter DD.1 with an open collector, and then on the intensifying VT1 transistor, developing then with supply voltage.
As a result of the done work the device representing the simulator of the telephone line for testing of phones and modems was designed. The developed device meets the requirements of the specification. Registration of design documentation conforms to requirements of ESKD. Documentation comprises the description of the principle of operation of the device, the block and full schematic diagram of the device, the program for the microcontroller and temporary charts of operation of the device.
As the microcontroller for work in the device it is possible to use the OBM 5 single-crystal computer It possesses the acceptable price and productivity and can be quite used as the microcontroller in the developed device. Besides, the developer has an opportunity to test the program for this OVM with use of the personal computer, by means of the AVSim51 emulator, for elimination of the syntactic and some logical mistakes which arose in the course of writing of the program.