
5.4RS-232C Serial Interface
The
5.4.1Hardware requirements
Signal levels:
Input circuit:
An MC1489AL or equivalent is used to convert from the
Figure 5.9 shows the RS-232C interface input circuit.
Figure 5.9 RS-232C interface input circuit
Output circuit:
An MC1488L or equivalent is used to convert from the TTL level to the
Figure 5.10 shows the RS-232C interface output circuit
+5 V
1000 pF
0 V