Microhard Systems MHX-900, Operating Manual

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MHX-900 Operating Manual: Appendix C Sample Schematic Diagram
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C. Sample Schematic Diagram
The following is a sample microprocessor implementation with a MICROCHIP PIC 16C74 and the MHX-900. The MHX-900
performs no level shifting on the serial port, so direct connection to the host microprocessor is possible.
DO NOT CONNECT THE MHX-900 TO RS 232 DRIVER OUTPUTS. DAMAGE TO THE UNIT MAY RESULT.
On this implementation, the onboard SCI of the PIC 16C74 is directly connected pins 22 and 23 of the MHX-900. The bi-
directional Port D is used for asserting or monitoring control signals from the MHX-900.
The RESET signal is a momentary active low signal asserted by the host microprocessor.
RESET initializes the MHX-900 and places the system in a known state. This signal should be set high after the host
microprocessor has been reset.
RXD
TXD
DCD
DTR
DSR
RTS
CTS
RESET
PIC16C74
MHX-900
22
23
21
24
26
27
28
10
Power Connections are not shown
RC7
RC6
RD0
RD1
RD2
RD3
RD4
RD6