74165.C   74165 Library Routine to expand no. of input lines /////////////////////////////////////////////////////////////////////////// //// Library for a 74165 Expanded Input Chip //// //// //// //// Any number of these chips may be connected in series to get //// //// 8 additional inputs per chip. The cost is 3 I/O pins for //// //// any number of chips. //// //// //// //// read_expanded_inputs(ei); Reads the array ei from the chips //// //// //// /////////////////////////////////////////////////////////////////////////// //// (C) Copyright 1996,1997 Custom Computer Services //// //// This source code may only be used by licensed users of the CCS C //// //// compiler. This source code may only be distributed to other //// //// licensed users of the CCS C compiler. No other use, reproduction //// //// or distribution is permitted without written permission. //// //// Derivative programs created using this software in object code //// //// form are not restricted in any way. //// //////////////////////////////////////////////////////////////////////////// #IFNDEF EXP_IN_ENABLE #define EXP_IN_ENABLE PIN_B3 #define EXP_IN_CLOCK PIN_B4 #define EXP_IN_DI PIN_B5 #define NUMBER_OF_74165 1 #ENDIF void read_expanded_inputs(byte *ei) { byte i; output_high(EXP_IN_CLOCK); output_low(EXP_IN_ENABLE); // Latch all inputs output_high(EXP_IN_ENABLE); for(i=1;i<=NUMBER_OF_74165*8;++i) { // Clock in bits to the ei structure shift_left(ei,NUMBER_OF_74165,input(EXP_IN_DI)); output_low(EXP_IN_CLOCK); output_high(EXP_IN_CLOCK); } output_low(EXP_IN_ENABLE); }

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