SP2-433-160 Datasheet, PDF (23/27 Pages) Radiometrix Ltd – UHF SpacePort Transceiver

APPENDIX - C
Example SP2 driver subroutines for Motorola 68HC11
D0
D1
D2
D3
TXA
TXR
RXA
RXR
PC3
PC2
PC1
PC0
HOST
PC7 ^HC11
PC6
PC5
PC4 _IRQ
figure 16: SP2 to HC11 µ-C interface
Packet transfers to / from the SP2 are best handled in the host by two subroutines :- OUT_BYTE &
IN_BYTE
Additionally LISTEN_BUS is called on completion of a packet transfer to the SP2 to return the data bus
to inputs (default state).
*********************************************************************
*
* CPU REGISTER EQUATIONS
*
*********************************************************************
*
*This section contains a few of the necessary register equations used
*in the example subroutines.
PORTC
EQU $1003
;ADDRESS OF SP2 PORT
DDRC
EQU $1007
;DATA DIRECTION REGISTER PORT-C
* Port-C7 = RX-accept OUTPUT
* Port-C6 = RX-request INPUT
* Port-C5 = TX-accept INPUT
* Port-C4 = TX-request OUTPUT
* Port-C3 = SP2 data bit-3
* Port-C2 = SP2 data bit-2
* Port-C1 = SP2 data bit-1
* Port-C0 = SP2 data bit-0
Radiometrix Ltd, SP2 data sheet
page 23