PIC16CXXX microcontrollers from Microchip Technology,
Inc., high-performance, EPROM-based 8-bit microcon-
trollers. Some of the members of this series (like the
PIC16C71 and PIC16C84) do not have an on-chip hard-
ware asynchronous serial port. This application note
describes the interrupt driven software implementation of
Asynchronous Serial I/O (Half Duplex RS-232 Communi-
cations) using PIC16CXXX microcontrollers. These
microcontrollers can operate at very high speeds with a
minimum of 250 ns cycle time (with input clock frequency
of 16 MHz). To test the RS-232 routines, a simple Digital
Voltmeter (DVM)/Analog Data Acquisition System has
been implemented using a PIC16C71, in which, upon
reception of a command from host (IBM PC-AT
), an 8-bit
value of the selected A/D channel is transmitted back to
the host.M Software Implementation of Asynchronous Serial I/O
AN555
Transmission of a byte is performed by calling the
Author: Amar Palacherla PutChar function and the data byte in the TxReg is
Microchip Technology transmitted out. Before calling this function (PutChar),
Code Update: Scott Fink the data must be loaded into TxReg and ensure the
Microchip Technology Inc. serial port is free. The serial port is free when both the
_txmtP……
