SHIn and Dwords strange behaviour ?

[kcsl]

Trying to write some software that captures 32 bits of data from a long shift register chain and backhauls the data to a PC via serial. Nothing too strenuous, or so I thought.

After things not working as I expected some experimentation was in order.

I'm using 4.0.1 build 3 of the compiler.
The PIC is an 18F25K22


The following works and proves my hardware and software is fine.

Code Select Expand

SHIn SR_QH, SR_SRCLK, MsbPre_L, [ bytBank0\8, bytBank1\8, bytBank2\8, bytBank3\8 ]
hrsout bin8 bytBank0, " ", bin8 bytBank1, 13, 10 ' Only interested in the first 2 banks for now.

I changed to this which works but gives a compiler warning which just says "***! ***"

Code Select Expand

dim dwTemp as DWord

SHIn SR_QH, SR_SRCLK, MsbPre_L, [ dwTemp\32 ]
hrsout hex8 dwtemp, 13, 10     

I removed the \32; I shouldn't need it as dwTemp is a DWord variable so 32 bits.
The compiler warning goes away, but now it just returns all zeros as the result.

Next I introduced an array of Dwords (which is what I ultimately wanted to do)
This works fine which proves that HRSOut is happy with arrays of Dwords.

Code Select Expand

dim dwHeap[10] as Dword

bytHeapPointer = 5
SHIn SR_QH, SR_SRCLK, MsbPre_L, [ dwTemp\32 ] ' seem to need the \32
dwheap[bytHeapPointer] = dwtemp
hrsout hex8 dwheap[bytHeapPointer], 13, 10

Finally I tried this (which is my original code and started me down this investigative path) which just returns crazy results.

Code Select Expand

bytHeapPointer = 5
SHIn SR_QH, SR_SRCLK, MsbPre_L, [ dwheap[bytHeapPointer]\32 ] ' seem to need the \32
hrsout hex8 dwheap[bytHeapPointer], 13, 10

My conclusion is that you need to have the \32 and you can't use array elements (at least Dword ones) with the SHIn command.

Or am I just doing something wrong ?

Kind regards,
Joe

[Yasin]

Necessary explanation is available on page 185 of the Positron8 manual.

Bits is an optional constant specifying how many bits (1-16) are to be input by Shin. If no bits
entry is given, Shin defaults to 8 bits.

[kcsl]

Necessary explanation is available on page 185 of the Positron8 manual.

That's brilliant Yasin... I thought I had to be doing something silly.
Thanks.

Regards,
Joe

[top204]

That is something I must add to future compiler builds, but it can be accomplished by something such as:

Dim dTemp As Dword

SHIn SR_QH, SR_SRCLK, MsbPre_L, [ dTemp.Word1\16 , dTemp.Word0\16 ]
MyDwordArray[bIndex] = dTemp

Where the Low and High words of the Dword variable are individually sent or received.