This example program is handy for familiarizing yourself with the mapping of the SPiceX inputs.
;IDENTIN.SPT : Sample program to identify which inputs get ;reflected in which bytes/bits of U when using the ;SPxTxfr instruction. ;The program senses just one expansion input turned on ;at a time. It reads in up to 8 bytes of input data using SPxTxfrU ;and saves them in RAM. It then inspects the RAM to find a set bit. ;Finally it displays the byte/bit number in onboard outputs ; 0-7. Bits 3-6 contain the byte number. Bits 0-2 contain the ;bit number within that byte. Bit 7 is BLINKed to signal the presence of data ;(otherwise byte 0, bit 0 would show nothing). ;You can also inspect the raw data using SPLatLink (The SL button ;in the Module window of SPLat/PC). ;Data is in locations 0 up, inverted. Click the Format button in the ;Data memory window to get binary formatting. **************************************************************** ;Set the following constant to reflect the number of bytes of ;data being shifted in. ; ; XBIO16 2 bytes ; MBIO16 2 bytes ; XIRO16 1 byte ; HIO16 1 byte ; FP16 1 byte ShiftLength EQU 8 ;Minimum 5 with standard expansion boards! **** NOTE **** ;SPiceX mode works only with standard XPice expansion boards when ;there are more than 4 bytes of data. For less than that the ;automatic detection will sense the boards and map them as ;regular I/O. ;With custom expansion boards it may work with fewer than 5 bytes, ;depending on the design of the board. Please consult the board documentation. **************************************************************** SPxMode 6 SetV ShiftLength ;Will henceforth control how ;many bytes get transferred ;Back here when no inputs are detected Nothing: LoadX 0 ;Data LoadX 255 ;Bit select mask for OutputM OutputM 0 ;Clear result display NextRead: ClrU ;Don't want any output data SPxTxfrU 0 ;Reads the inputs UVToMem 0,0 ;Copy V bytes from U to memory ;Identify the first non-zero byte. I is used as a counter/pointer LoadI ShiftLength ByteLoop: ItoX ;Check the counter/pointer Push GoIfZ Nothing ;Exhausted all bytes DecX ;Bump the pointer XtoI iRecall 0 ;Get byte pointed to by I notm ;Raw input data is inverted GoIfZ ByteLoop ;Fall down here if we found a NZ byte ItoX ;Byte number LoadX 7 ;Select 3 bits of byte number OutputM 3 ;Display ;Identify the first NZ bit within the byte. We know the ;byte is NZ, so there's no need to defend against not finding ;a bit set. iRecall 0 ;Get back the byte pointed to by I notm ;Raw input data is inverted LoadI 0 ;Use I as a counter BitLoop: Push LoadX 1 ;a mask AndM ;select bit 0 GoIfNZ FoundBit IncI RORM GoTo BitLoop FoundBit: ItoX LoadX 7 OutputM 0 Blink 7 GoTo NextRead