PK70 Multifunction board Slow Analog Read Speed

[tony]

There is no spec on how fast the read speed is for the analog inputs on this board are. I was trying to read at 1000 samples per second but could only get about 100 samples per second. The spec for the MAX197 chip is 100ksps and it's running on a parallel bus so I assume 1000 sps shouldn't be a problem. I am able to read digital inputs for the same board at 1000 sps without any issues.

I configured the analog input pin as follows:
NBPKBM_J1[12].function( P12_FUNCTION_ADV0_5 );

and was reading it using:
adValue = NBPKBM_J1[12];

I setup a timer interrupt routine using the PIT application note to run at 1000hz and was posting to a semaphore that a task was pending on.

SetUpPITR( 1 /* Use PIT1 */, 4607 /* Wait 4607 clocks */, 4 /*Divide by 16 from table 213(2^4) */ );

I'm not sure if there is a conflict with the PIT timer I am using or a problem with the library supplied with the Multifunction board. I am using release rel22_rc1 of the Eclipse tools.

Cheers,
Tony

[tony]

I noticed that there was a busy loop in the function ReadAnalogPin in the file NBPKBM.cpp

Code: Select all

   volatile int i;
   for ( i = 0; i < 10000; i++ )
   {
      asm(" nop");
   }

When I put a scope on the WR line of the ADC I notice that is was held low for about 10ms. Is this by design or left over from some debugging? I first removed the busy loop which stopped the ADC from working. In the end I change the count from 10,000 to 10. The ADC appears to working fine. Any comment would be appreciated.

Cheers,
Tony

[tony]

I submitted a ticket to Netburner and recieved this source code which I have been given permission to share. With this code I was able to read a single channel at about 40ksps.

Code: Select all

#include "predef.h"
#include <stdio.h>
#include <ctype.h>
#include <startnet.h>
#include <autoupdate.h>
#include <dhcpclient.h>
#include <smarttrap.h>
#include <taskmon.h>
#include <bsp.h>
#include <..\pk70\system\sim5270.h>
#include <cfinter.h>


extern "C" {
void UserMain(void * pd);
void SetIntc(long func, int vector, int level, int prio );

}


const char * AppName="PK70Ad";

#define BASEADDRESS 0xA0000000

volatile unsigned char* pAtoD;

DWORD ad_isrcnt;

OS_SEM AdFinishedPostSem; /* We are going to use a Semaphore to notify
when A/D is done */

volatile WORD * pResults;
volatile WORD * pChannels;
volatile int curpos;
volatile int num_entries;



INTERRUPT(out_irq1_pin_isr, 0x2100 )
{
/* WARNING WARNING WARNING
Only a very limited set of RTOS functions can be called from
within an interrupt service routine.

Basically, only OS POST functions and LED functions should be used
No I/O (read, write or printf may be called), since they can block. */

sim.eport.epfr=0x02; /* Clear the interrupt edge 0 0 0 0 0 0 1 0 */
ad_isrcnt++;

if(pResults)
{
PBYTE pb = ( PBYTE )&(pResults[curpos]);
pb[0] = pAtoD[1];
pb[1] = pAtoD[0];
curpos++;
if (curpos<num_entries)
{
pAtoD[0]=pChannels[curpos];
}
else
{
OSSemPost(&AdFinishedPostSem);
}
}
}





void InitADCS()
{

/* Next we set up the A/D Clock */
sim.gpio.par_timer |= 0xC0; /* Set DTOUT3 to be an output at ~2Mhz. */
sim.timer[3].trr = 19;
sim.timer[3].tcn = 0;
sim.timer[3].txmr = 0;
sim.timer[3].tmr = 0x002B;


/* Set up the chip select */
sim.cs[1].csar = ( BASEADDRESS >> 16 );
sim.cs[1].cscr = 0x2140; /* 0010 0001 0110 0000 */
sim.cs[1].csmr = 0x001F0001;


pAtoD = ( PBYTE )BASEADDRESS;


OSSemInit(&AdFinishedPostSem,0);

sim.eport.eppar=0x0008; /* 00 00 00 00 00 00 10 00 see table
15-3 in UM */

sim.eport.epddr=0x0; /* All edge port pins as inputs */
sim.eport.epier = 0x0002; /* Enable IRQ1 only 0 0 0 0 0 0 1 0 */

/* Now enable the actual interrupt controller. See users manual chapter
10 for
more information. We are going to use the BSP helper function declared
above and
implemented in BSP.c */
SetIntc(
(long)&out_irq1_pin_isr, /* Our interrupt function */
1, /* The vector number from the users manual table 10-13 */
1, /* Set this to priority 1 but any value from 1 to 6 would
be valid.*/
1 /* The priority within the gross levels; see chapter 10, any
value from 0 to 7 is ok */
);





}




WORD ReadAD(BYTE ch)
{
*pAtoD = ch;
OSSemPend(&AdFinishedPostSem,20);
WORD w;
PBYTE pb = ( PBYTE )&w;
pb[0] = pAtoD[1];
pb[1] = pAtoD[0];
return w;
}


#define SCALE0_5 (0)
#define SCALE0_10 (0x10)
#define SCALEM5_5 (0x08)
#define SCALEM10_10 (0x18)


void GetConversionSet(int nch, WORD * pWhatToConvert, WORD * ipResults)
{
pResults=ipResults;
pChannels=pWhatToConvert;
curpos=0;
num_entries=nch;


*pAtoD=pWhatToConvert[0]; //Kick it all off
OSSemPend(&AdFinishedPostSem,20);
}





void UserMain(void * pd)
{
InitializeStack();/* Setup the TCP/IP stack buffers etc.. */

GetDHCPAddressIfNecessary();/*Get a DHCP address if needed*/
/*You may want to add a check for the return value from this function*/
/*See the function definition in \nburn\include\dhcpclient.h*/

OSChangePrio(MAIN_PRIO);/* Change our priority from highest to
something in the middle */

EnableAutoUpdate();/* Enable the ability to update code over the
network */

EnableSmartTraps();/* Enable the smart reporting of traps and faults */

EnableTaskMonitor();/*Enable the Task scan utility */


iprintf("Application started\n");

InitADCS();

WORD ConvertArray[8];

ConvertArray[0]=0|SCALE0_5;
ConvertArray[1]=1|SCALEM5_5;
ConvertArray[2]=2|SCALEM5_5;
ConvertArray[3]=3|SCALEM5_5;
ConvertArray[4]=4|SCALE0_10;
ConvertArray[5]=5|SCALEM10_10;
ConvertArray[6]=6|SCALEM10_10;
ConvertArray[7]=7|SCALEM10_10;


OSTimeDly(20);
iprintf("AD ISR= %d\r\n",ad_isrcnt);

while (1)
{
OSTimeDly(TICKS_PER_SECOND * 1);
WORD results[8];
GetConversionSet(8,ConvertArray,results);
for(int i=0; i<8; i++) printf("ADvalue[%d]=%d\r\n",ad_isrcnt,i,results[i]);
}
}