Diff: example2.cpp

Revision:

8:cb4d323ce6fd

Child:

9:e7ecf909e834

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/example2.cpp	Sat Feb 05 08:53:26 2011 +0000
@@ -0,0 +1,140 @@
+#ifdef COMPILE_EXAMPLE2_CODE_MODDMA
+
+/*
+ * This example was provided to support Mbed forum thread:-
+ * http://mbed.org/forum/mbed/topic/1798
+ */
+ 
+#include "mbed.h"
+#include "MODDMA.h"
+
+#define SAMPLE_BUFFER_LENGTH 32
+
+DigitalOut led1(LED1);
+DigitalOut led2(LED2);
+
+MODDMA dma;
+Serial pc(USBTX, USBRX);
+
+// ISR set's this when transfer complete.
+bool dmaTransferComplete = false;
+
+// Function prototypes for IRQ callbacks.
+// See definitions following main() below.
+void TC0_callback(void);
+void ERR0_callback(void);
+
+int main() {
+
+    // Create a buffer to hold the ADC samples and clear it.
+    // Note, we are going to sample two ADC inputs so they
+    // end up in this buffer "interleaved". So you will want
+    // a buffer twice this size to a real life given sample
+    // frequency. See the printf() output for details.
+    uint32_t adcInputBuffer[SAMPLE_BUFFER_LENGTH];    
+    memset(adcInputBuffer, 0, sizeof(adcInputBuffer));
+    
+    // We use the ADC irq to trigger DMA and the manual says
+    // that in this case the NVIC for ADC must be disabled.
+    NVIC_DisableIRQ(ADC_IRQn);
+    
+    // Power up the ADC and set PCLK
+    LPC_SC->PCONP    |=  (1UL << 12);
+    LPC_SC->PCLKSEL0 &= ~(3UL << 16); // PCLK = CCLK/4 96M/4 = 24MHz
+    
+    // Enable the ADC, 12MHz,  ADC0.0 & .1
+    LPC_ADC->ADCR  = (1UL << 21) | (1UL << 8) | (3UL << 0); 
+    
+    // Set the pin functions to ADC
+    LPC_PINCON->PINSEL1 &= ~(3UL << 14);  /* P0.23, Mbed p15. */
+    LPC_PINCON->PINSEL1 |=  (1UL << 14);
+    LPC_PINCON->PINSEL1 &= ~(3UL << 16);  /* P0.24, Mbed p16. */
+    LPC_PINCON->PINSEL1 |=  (1UL << 16);
+    
+    // Setup the serial port to print out results.
+    pc.baud(115200);
+    pc.printf("ADC with DMA example\n");
+    pc.printf("====================\n");
+    
+    // Prepare an ADC configuration.
+    MODDMA_Config *conf = new MODDMA_Config;
+    conf
+     ->channelNum    ( MODDMA::Channel_0 )
+     ->srcMemAddr    ( 0 )
+     ->dstMemAddr    ( (uint32_t)adcInputBuffer )
+     ->transferSize  ( SAMPLE_BUFFER_LENGTH )
+     ->transferType  ( MODDMA::p2m )
+     ->transferWidth ( MODDMA::word )
+     ->srcConn       ( MODDMA::ADC )
+     ->dstConn       ( 0 )
+     ->dmaLLI        ( 0 )
+     ->attach_tc     ( &TC0_callback )
+     ->attach_err    ( &ERR0_callback )
+    ; // end conf.
+    
+    // Prepare configuration.
+    dma.Setup( conf );
+    
+    // Enable configuration.
+    dma.Enable( conf );
+    
+    // Enable ADC irq flag (to DMA).
+    // Note, don't set the individual flags,
+    // just set the global flag.
+    LPC_ADC->ADINTEN = 0x100;
+
+    // Enable burst mode on inputs 0 and 1.
+    LPC_ADC->ADCR |= (1UL << 16); 
+    
+    while (1) {
+        // When transfer complete do this block.
+        if (dmaTransferComplete) {
+            delete conf; // No memory leaks, delete the configuration.
+            dmaTransferComplete = false;
+            for (int i = 0; i < SAMPLE_BUFFER_LENGTH; i++) {
+                int channel = (adcInputBuffer[i] >> 24) & 0x7;
+                int iVal = (adcInputBuffer[i] >> 4) & 0xFFF;
+                double fVal = 3.3 * (double)((double)iVal) / ((double)0x1000); // scale to 0v to 3.3v
+                pc.printf("Array index %02d : ADC input channel %d = 0x%03x %01.3f volts\n", i, channel, iVal, fVal);                  
+            }
+        }
+        
+        // Just flash LED1 for something to do.
+        led1 = !led1;
+        wait(0.25);        
+    }
+}
+
+// Configuration callback on TC
+void TC0_callback(void) {
+    
+    MODDMA_Config *config = dma.getConfig();
+    
+    // Disbale burst mode and switch off the IRQ flag.
+    LPC_ADC->ADCR &= ~(1UL << 16);
+    LPC_ADC->ADINTEN = 0;    
+    
+    // Finish the DMA cycle by shutting down the channel.
+    dma.haltAndWaitChannelComplete( (MODDMA::CHANNELS)config->channelNum());
+    dma.Disable( (MODDMA::CHANNELS)config->channelNum() );
+    
+    // Tell main() while(1) loop to print the results.
+    dmaTransferComplete = true;            
+    
+    // Switch on LED2 to show transfer complete.
+    led2 = 1;        
+    
+    // Clear DMA IRQ flags.
+    if (dma.irqType() == MODDMA::TcIrq) dma.clearTcIrq();    
+    if (dma.irqType() == MODDMA::ErrIrq) dma.clearErrIrq();
+}
+
+// Configuration callback on Error
+void ERR0_callback(void) {
+    // Switch off burst conversions.
+    LPC_ADC->ADCR |= ~(1UL << 16);
+    LPC_ADC->ADINTEN = 0;
+    error("Oh no! My Mbed EXPLODED! :( Only kidding, go find the problem");
+}
+
+#endif