arneme@stud.cs.uit.no (Arne M-Ellingsen) (10/10/90)
I am working on a project where we wish to use the Eikonix 1400 Scanner to
digitize images. The scanner uses the GPIB (HP-IB) bus for communication
with a Mac-II that has a NI-488 board in slot 2. The version of the NI-488
driver software is 3.0. For some reason we are not able to do asynchronous
DMA transfers of scan lines from the Scanner. In the NI-488 documentation
the routines ibdma (for initialization) and ibrda (for asynchronous reading
of data using DMA from the GPIB bus) are said to allow for DMA transfer. ibwait
is a routine that according to the documentation could be used to wait for
events on the bus. We use this routine to wait for I/O completion of scan
line transfers and thus synchronize with the scanner.
Her are samples of the code we are using : (Think C v. 4.0 )
void Init_DMA(int BrdNo)
/* Used to prepare the NI-488 for DMA transfer */
{
if (BrdNo)
ibdma( BrdNo, 1);
}
int Wait_Asynk(int lun)
/* Used to synchronize with the NI-488 board */
{
return ibwait(ccs[lun]->dig_number, CMPL);
}
int Read_Asynk12( int lun, word *data, int npixels, int nsteps, int nscans)
/*
Scan 12 bit data, several lines at a time, under dma control (?)
*/
{
extern char cmd[];
long args[3];
long count;
int status;
args[0] = nsteps;
args[1] = nscans;
/* Make comand to the scanner to start scan using DMA (10 = 7 + 3
where 7 indicates the use of DMA and 3 indicates 12 bit data) */
make_cmd( 10, 2, args, cmd);
/* Send the command to the scanner. This will start the scan */
if (status = sndcmd( lun, cmd) != NORMAL)
return status;
count = 2L * npixels * nscans;
/* Read the scan data using DMA (doesn't seem to work) */
status = ibrda( ccs[lun]->dig_number, data, count);
return status;
}
Somewhere in the code :
/* Initialize the NI-488 board to prepare for DMA transfers */
Init_DMA( TheBoard);
/* Prepare to receive the first line from the scanner */
scannerstat = Read_Asynk12( lun, Stripe[1], ScanW, SkipL, InStripLength);
/* Do this while there is more lines to read */
while (PixLin < PictL) {
/* Synchronize with scanner */
Wait_Asynk(lun);
if (LinjerLest < ScanL) { /* If not last line */
scannerstat = Read_Asynk12( lun, Stripe[TilBuf], ScanW, SkipL, InStripLength);
if (scannerstat != NORMAL) break;
LinjerLest += InStripLength*SkipL;
} else /* Last line, send stage home */
idahom( lun, &stat);
/* Here comes code that processes the last received scan line
while the next line should be reiceived to DMA memory. The
code is ommited */
}
Any suggestions on what might be the problem ?
____________________________________________________________
| Arne Munch-Ellingsen |
| Department of Computer Science, University of Tromsoe |
| Postboks 953, N-9000 TROMSOE, NORWAY. |
| |
| Phone :+478344034 |
| +478344053 |
| +478380298 (Home phone) |
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| E-mail: arneme@cs.uit.no |
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