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Visitor
Visitor
8,941 Views
Registered: ‎02-02-2009

Using the Spartan 3E Starter Kit ADC with Microblaze

Hi all,

 

I'm trying to get my ADC to work using Microblaze and C code.  I set the amp using my writeSPI() function, which works on the DAC just fine.  However, with the ADC, the AD_CONV signal is throwing me off.  I'm trying to use the SPISSR register to control it like my other SPI devices, but the user's guide said the SS register is an active-low register.  Does this mean that SCK won't output unless one of the vectors is low?  Here's my code for the ADC function:

 

int readADC()
{
    unsigned int numBytes = 4;
    int i;
    unsigned int adc_data = 0;
    int adc_a=0, adc_b=0;
   
    SPI_DEV_CTL=0x6;  // Turn off DAC, AMP, and Flash memory

   
    while(SPISSR!=deviceMask);        // Must wait for last transaction to finish
   
    SPICR=0x08E;    // Change SCK Polarity to high

    SPISSR=~0;                            // Assert AD_CONV to begin data conversion        
    SPISSR=~0x04;                        // Deassert AD_CONV
   
    // Wait 32 SCK cycles for ADCs to be read
    //for(i=0; i<1000;i++);
   
    SPISSR=~0;                            // Assert AD_CONV to begin sending on MISO
    SPISSR=~0x04;                        // Deassert AD_CONV
       
    for(; numBytes; --numBytes)                    // Read in each byte from Rx FIFO
        adc_data=(adc_data<<8)|(SPIDRR&0x0FF);            // "Append" to LSB of value
   
    adc_a = ((adc_data & 0xFFFC000) >> 14);
    adc_b = (adc_data & 0x3FFF);
   
    writeLcd(LCD_CMD, 0x01);
    printLcd("ADC A: ");
    display_num(adc_data);
    writeLcd(LCD_CMD, 0xC0);
    printLcd("ADC B: ");
    display_num(adc_b);
    for(i=0;i<100000000;i++);
   
    //SPISSR=~0;
    SPICR=0x086;    // Change SCK Polarity back to low
   
    return adc_a;
}
 

This code is a work in progress, so many things are commented out for testing.  The SS register is as follows:

 

bit0 = DAC

bit1 = AMP

bit2 = ADC

 

SPI_DEV_CTL is a macro that is linked to a GPIO that controls the DAC CLR, AMP SHDN, and flash CEN signals.  I've set up several macros for the SPI registers (i.e. SPIDRR) which are volatile entries in my header file:

 

/*******************************************
 * spi.h
 *******************************************/
 
#ifndef SPI_H
#define SPI_H

#define SPI_DEV_CTL_DD    (*(volatile unsigned long *)(XPAR_SPI_DEV_CTL_BASEADDR+0x04))
#define SPI_DEV_CTL        (*(volatile unsigned long *)(XPAR_SPI_DEV_CTL_BASEADDR+0x00))
#define disableSPI()        {SPI_DEV_CTL=0x6;}

#define AMP_DOUT_DD    (*(volatile unsigned long *)(XPAR_AMP_DOUT_BASEADDR+0x04))
#define AMP_DOUT        (*(volatile unsigned long *)(XPAR_AMP_DOUT_BASEADDR+0x00))

#define    SPICR        (*(volatile unsigned long *)(XPAR_OPB_SPI_0_BASEADDR+0x60))
#define    SPISR        (*(volatile unsigned long *)(XPAR_OPB_SPI_0_BASEADDR+0x64))
#define    SPIDTR    (*(volatile unsigned long *)(XPAR_OPB_SPI_0_BASEADDR+0x68))
#define    SPIDRR    (*(volatile unsigned long *)(XPAR_OPB_SPI_0_BASEADDR+0x6C))
#define    SPISSR    (*(volatile unsigned long *)(XPAR_OPB_SPI_0_BASEADDR+0x70))
#define    SPIGIE    (*(volatile unsigned long *)(XPAR_OPB_SPI_0_BASEADDR+0x1C))
#define    SPIISR    (*(volatile unsigned long *)(XPAR_OPB_SPI_0_BASEADDR+0x20))
#define    SPIIER    (*(volatile unsigned long *)(XPAR_OPB_SPI_0_BASEADDR+0x28))
#define    SPIRXF    (*(volatile unsigned long *)(XPAR_OPB_SPI_0_BASEADDR+0x78))

#define    SPI_DAC    0x01
#define    SPI_AMP    0x02
#define    SPI_ADC    0x04

#define FLASH 0x03

#define DAC_A 0x00
#define DAC_B 0x01
#define DAC_C 0x02
#define DAC_D 0x03
#define DAC_ALL 0x0F

#define    sendDAC(n,val)        writeSPI(SPI_DAC, 0x00300000 | (((n)&0x0F)<<16) | (((val)&0x0FFF)<<4), 4)
#define    sendAmp(a,b)        writeSPI(SPI_AMP, (((b)&0x07)<<4) | ((a)&0x07), 1)

#define  readADC()           readSPI(SPI_ADC, 2)

void initSPI(void);
void clearSPI(void);
int readSPI(unsigned int numBytes);
void writeSPI(unsigned int device, unsigned int value, unsigned int numBytes);

#endif
 

 

I'm focusing on the CPOL and CPHA values right now, since changing it to a idle-high clock gave me some results.  However, I think I'm just reading what's left on the MISO line after setting the amp; there's no information coming from the ADC.

 

Any info or code snippets would be great.  Thanks!

 

Matt

7 Replies
Highlighted
Visitor
Visitor
7,453 Views
Registered: ‎11-27-2010

Re: Using the Spartan 3E Starter Kit ADC with Microblaze

I was sorry to see no one helped with this as I have the same question.  Does anyone have an example of a C++ method to read from the ADC (With a Spartan board w/ microblaze)

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Highlighted
Xilinx Employee
Xilinx Employee
7,442 Views
Registered: ‎01-03-2008

Re: Using the Spartan 3E Starter Kit ADC with Microblaze

It is likely that the original question was re-posted and answered in the Embedded Processing forums which would have the right audience to be able to help.

------Have you tried typing your question into Google? If not you should before posting.
Too many results? Try adding site:www.xilinx.com
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Highlighted
Visitor
Visitor
7,433 Views
Registered: ‎11-27-2010

Re: Using the Spartan 3E Starter Kit ADC with Microblaze

Actually I have.  I have searched through every community posting with the key words analog digital | a/d | adc & microblaze.  I have found instances of people asking similar questions, but no examples of helpful solutions or example communications using C/C++.  I did however find plenty of condescending redirects.  

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Highlighted
Visitor
Visitor
6,997 Views
Registered: ‎02-07-2011

Re: Using the Spartan 3E Starter Kit ADC with Microblaze

i thing that your problem is th gain of the op amp. You should set the gain vector otherwise the opamp return 0.

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Highlighted
6,592 Views
Registered: ‎09-29-2011

Spartan 3A Starter Kit ADC Microblaze

Hello,

I am trying to add an xps_adc ip core to a Microblaze processor,but i have a few questions.

1.)What others peripherals do I need to add?

2.)What do the xps_adc's port signify and how should i connect them?

Thank you.

Tags (1)
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Highlighted
Instructor
Instructor
6,585 Views
Registered: ‎07-21-2009

Re: Spartan 3A Starter Kit ADC Microblaze

chiforbogdan86,

 

Please start a new thread for this topic, in the Embedded Processing forum.

 

It is considered bad manners to bring a new and unrelated topic or question into an existing thread.  This practice makes a mess of the discussions, similar to multiple conversations in a small and crowded room.

 

Thank you for your consideration.

 

-- Bob Elkind

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Highlighted
Visitor
Visitor
6,293 Views
Registered: ‎04-30-2012

Re: Using the Spartan 3E Starter Kit ADC with Microblaze

Could you post your project ? thank you
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