dsPIC ADC scanning through

[gast (Gast)]

Hallo,
ich bin dabei, den ADC meines dsPIC33F in Betrieb zu nehmen. Ich möchte 
5 channels (AIN0-AIN4) sequentiell im 12-bit mode durchscannen und 
mittels DMA die Resultate abspeichern. Dazu habe ich den example code 
16-4 aus dem 33F manual 
(http://ww1.microchip.com/downloads/en/DeviceDoc/70183A.pdf) genommen 
und einige Anpassungen gemacht, da dieser Code dort nur für 4 channels 
(AIN0-AIN3) ist. Meine Anpasssungen sind folgende:

- AD1CON1bits.FORM = 0;
- AD1CON1bits.AD12B = 1;
- AD1CSSL = 0x001F;
- AD1CON2bits.SMPI = 4;
- DMA0CNT = 39;

Nun ja, irgendwie funktioniert mein Code leider nicht. Wenn ich aber nur 
4 channels scanne, dann gehts einwandfrei.

vielen dank für die Hilfe!

/*==========================================================================================
ADC Initialization for Channel Scan
===========================================================================================*/
void adcInit(void){
initDma0();

AD1CON1bits.FORM = 0; // Data Output Format: Signed Fraction (Q15
format)
AD1CON1bits.SSRC = 2; // Sample Clock Source: GP Timer starts conversion
AD1CON1bits.ASAM = 1; // ADC Sample Control: Sampling begins immediately
after conversion
AD1CON1bits.AD12B = 1; // 12-bit ADC operation
AD1CON1bits.SIMSAM = 0; // Samples multiple channels individually in
sequence
AD1CON2bits.BUFM = 0;
AD1CON2bits.CSCNA = 1; // Scan Input Selections for CH0+ during Sample A
bit
AD1CON2bits.CHPS = 0; // Converts CH0
AD1CON3bits.ADRC = 0; // ADC Clock is derived from Systems Clock
AD1CON3bits.ADCS = 63; // ADC Conversion Clock
//AD1CHS0: A/D Input Select Register
AD1CHS0bits.CH0SA = 0; // MUXA +ve input selection (AIN0) for CH0
AD1CHS0bits.CH0NA = 0; // MUXA -ve input selection (Vref-) for CH0

//AD1CHS123: A/D Input Select Register
AD1CHS123bits.CH123SA = 0; // MUXA +ve input selection (AIN0) for CH1
AD1CHS123bits.CH123NA = 0; // MUXA -ve input selection (Vref-) for CH1
//AD1CSSL: A/D Input Scan Selection Register
AD1CSSL = 0x001F; // Scan AIN0, AIN1, AIN2, AIN3, AIN4 inputs
AD1CON1bits.ADDMABM = 0; // DMA buffers are built in scatter/gather mode
AD1CON2bits.SMPI = 4; // 5 ADC buffers
AD1CON4bits.DMABL = 3; // Each buffer contains 8 words
IFS0bits.AD1IF = 0; // Clear the A/D interrupt flag bit
IEC0bits.AD1IE = 0; // Do Not Enable A/D interrupt
AD1CON1bits.ADON = 1; // Turn on the A/D converter
initTmr3();
}
/*======================================================================================
Timer 3 is setup to time-out every 125 microseconds (8Khz Rate). As a
result, the module
will stop sampling and trigger a conversion on every Timer3 time-out,
i.e., Ts=125us.
=======================================================================================*/
void initTmr3(void)
{
TMR3 = 0x0000;
PR3 = 4999; // Trigger ADC1 every 125usec
IFS0bits.T3IF = 0; // Clear Timer 3 interrupt
IEC0bits.T3IE = 0; // Disable Timer 3 interrupt
T3CONbits.TON = 1; //Start Timer 3
}

// Linker will allocate these buffers from the bottom of DMA RAM.
struct
{
unsigned int Adc1Ch0[8];
unsigned int Adc1Ch1[8];
unsigned int Adc1Ch2[8];
unsigned int Adc1Ch3[8];
unsigned int Adc1Ch4[8];
} BufferA __attribute__((space(dma)));

struct
{
unsigned int Adc1Ch0[8];
unsigned int Adc1Ch1[8];
unsigned int Adc1Ch2[8];
unsigned int Adc1Ch3[8];
unsigned int Adc1Ch4[8];
} BufferB __attribute__((space(dma)));
// DMA0 configuration
// Direction: Read from peripheral address 0-x300 (ADC1BUF0) and write
to DMA RAM
// AMODE: Peripheral Indirect Addressing Mode
// MODE: Continuous, Ping-Pong Mode
// IRQ: ADC Interrupt

void initDma0(void)
{
DMA0CONbits.AMODE = 2; // Configure DMA for Peripheral indirect mode
DMA0CONbits.MODE = 2; // Configure DMA for Continuous Ping-Pong mode
DMA0PAD = 0x0300; // Point DMA to ADC1BUF0
DMA0CNT = 39; // 40 DMA request (4 buffers, each with 8 words)
DMA0REQ = 13; // Select ADC1 as DMA Request source
DMA0STA = __builtin_dmaoffset(&BufferA);
DMA0STB = __builtin_dmaoffset(&BufferB);
IFS0bits.DMA0IF = 0; //Clear the DMA interrupt flag bit
IEC0bits.DMA0IE = 1; //Set the DMA interrupt enable bit
DMA0CONbits.CHEN=1; // Enable DMA
}

/*========================================================================================
_DMA0Interrupt(): ISR name is chosen from the device linker script.
========================================================================================*/
unsigned int DmaBuffer = 0;
void __attribute__((_interrupt_)) _DMA0Interrupt(void)
{
if(DmaBuffer == 0){
xMsb = (unsigned char)(BufferA.Adc1Ch0[1] >> 8);
xLsb = (unsigned char)(BufferA.Adc1Ch0[1] & 0xFF);
yMsb = (unsigned char)(BufferA.Adc1Ch1[1] >> 8);
yLsb = (unsigned char)(BufferA.Adc1Ch1[1] & 0xFF);
vrefMsb = (unsigned char)(BufferA.Adc1Ch2[1] >> 8);
vrefMsb = (unsigned char)(BufferA.Adc1Ch2[1] & 0xFF);
temperatureMsb = (unsigned char)(BufferA.Adc1Ch3[1] >> 8);
temperatureLsb = (unsigned char)(BufferA.Adc1Ch3[1] & 0xFF);
zMsb = (unsigned char)(BufferA.Adc1Ch4[1] >> 8);
zLsb = (unsigned char)(BufferA.Adc1Ch4[1] & 0xFF);

}
else
{
xMsb = (unsigned char)(BufferB.Adc1Ch0[1] >> 8);
xLsb = (unsigned char)(BufferB.Adc1Ch0[1] & 0xFF);
yMsb = (unsigned char)(BufferB.Adc1Ch1[1] >> 8);
yLsb = (unsigned char)(BufferB.Adc1Ch1[1] & 0xFF);
vrefMsb = (unsigned char)(BufferB.Adc1Ch2[1] >> 8);
vrefMsb = (unsigned char)(BufferB.Adc1Ch2[1] & 0xFF);
temperatureMsb = (unsigned char)(BufferB.Adc1Ch3[1] >> 8);
temperatureLsb = (unsigned char)(BufferB.Adc1Ch3[1] & 0xFF);
zMsb = (unsigned char)(BufferB.Adc1Ch4[1] >> 8);
zLsb = (unsigned char)(BufferB.Adc1Ch4[1] & 0xFF);
}

DmaBuffer ^= 1;
IFS0bits.DMA0IF = 0; //Clear the DMA0 Interrupt Flag
}

[gast (Gast)]

AMODE = 0;