资料介绍
This application note describes how to connect a
PICmicro microcontroller device to a standard analog
telephone line in order to send and receive single and
multiple frequency signals through modulation and
demodulation (i.e., MODEM). Although there are many
different elements within a modem system, we are only
concerned here with the line connection. AN854
Connecting a PICmicro Microcontroller to a Standard Analog Telephone Line
Figure 1 shows how the ring and tip lines run into the
Author: David Hedley primary of a transformer. The hookswitch on the line
Microchip Technology Inc. side of the transformer is not shown but can be imple-
mented with opto-couplers, relays or switches. When a
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