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Date:	Thu, 20 May 1999 09:59:30 PDT
From:	Steven Levine <steve53@earthlink.net >
Reply-To:	scoug-programming@scoug.com
To:	scoug-programming@scoug.com
Subject:	SCOUG-Programming: #5

In <08256777.002356D8.00@svdatsmtpmta.beckman.com>, on 05/19/99
at 10:24 PM, "Benedict G Archer" said:

>But Steven, I've never written a driver in DOS,

OK, here's a sample. Other devices are more or less complex :). And,
don't bit about the hard coded 100uSec delay. I'll fix it someday.

>lasers, galvo-scanners, array sensors such as a linear diode array or
>ccd). The cards have been various, all with DOS drivers and usually with
>a library of functions (supplied with the card) linked into a C program

This is just wrappers. You still banging bits to and from the device.

Steven

--
-----------------------------------------------------------
Steven Levine MR2/ICE #10183
-----------------------------------------------------------
/*=== ADCInit: Initialize ADC ===*/

void ADCInit(BYTE idbRange)
{
outportb(ADC_BASE + 3, idbRange); // Init range

} // ADCInit

/*=== ADCRead: Read ADC channel ===*/

BOOL ADCRead(BYTE ibChan, short *psADCData)
{
USHORT c;
BYTE low;
BYTE high;
short sADData;
BOOL fOK;

outportb(ADC_BASE + 2, ibChan); // select A/D channel
for (c = 1; c < 25; c++)
; // wait 100 uSec for mux to settle - fixme to time

outportb(ADC_BASE + 1, 0); // start 12 bit conversion

while (inportb(ADC_BASE + 2) & ADC_BUSY && ++c < 500)
; // Wait for conversion to complete

fOK = c < 500; // False if conversion timeout

/* Read 12 bit ADC value
Data comes in normalized with MSB in bit 15 of data word
*/
low = inportb(ADC_BASE);
high = inportb(ADC_BASE + 1);
sADData = ((USHORT)high << 8) | low;
sADData -= 0x8000; // Remove offset
sADData = sADData >> 4; // Scale to 12 bits
*psADCData = sADData; // Stow

return fOK;

} // ADCRead

/*=== ADCReadStatus: Read ADC status word ===*/

BYTE ADCReadStatus(void)
{
return inportb(ADC_BASE + 2);

} // ADCReadStatus

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