Diff: example3.h

Revision:

12:1dfee7208043

Child:

13:846c8b6ffb7f

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/example3.h	Sun Mar 13 23:28:21 2011 +0000
@@ -0,0 +1,125 @@
+/*
+ * Demonstrates capturing the GPIO P0.4 to P0.7 "nibble" to memory 
+ * using GPDMA. The transfers from port pins to memory buffer are
+ * triggered using Timer1 MAT1.0 match compare.
+ *
+ * In this example all inputs have pullups. So with nothing connected
+ * the P0.4/7 reads as 0xF. Connecting a wire from one or more of the four 
+ * inputs to ground will show up in the captured buffer sequence.
+ */
+ 
+#include "mbed.h"
+#include "MODDMA.h"
+#include "iomacros.h" // within MODDMA library.
+
+// How long between grabbing GPIO FIO0PIN register.
+// Value is in microseconds. (50000 is half a second).
+#define SAMPLE_PERIOD   500000
+
+#define NUM_OF_SAMPLES  5
+
+Serial pc(USBTX, USBRX);
+
+DigitalOut led1(LED1);
+DigitalOut led2(LED2);
+DigitalOut led3(LED3);
+
+uint32_t buffer[NUM_OF_SAMPLES];
+
+bool dmaTransferComplete;
+
+MODDMA dma;
+MODDMA_Config *conf;
+
+void TC0_callback(void);
+void ERR0_callback(void);
+
+int main() {
+    
+    // Macros defined in iomacros.h, saves messing with DigitalIn
+    p30_AS_INPUT; p30_MODE( PIN_PULLUP ); // P0.4
+    p29_AS_INPUT; p29_MODE( PIN_PULLUP ); // P0.5
+    p8_AS_INPUT;  p8_MODE( PIN_PULLUP );  // P0.6
+    p7_AS_INPUT;  p7_MODE( PIN_PULLUP );  // P0.7
+    
+    // Clear the buffer.
+    memset(buffer, 0, sizeof(buffer));
+    
+    // Setup the serial port to print out results.
+    pc.baud(115200);
+    pc.printf("Starting up...\n");
+    
+    // Set-up timer1 as a periodic timer.
+    LPC_SC->PCONP    |= (1UL << 2); // TIM1 On
+    LPC_SC->PCLKSEL0 |= (3UL << 4); // CCLK/8 = 12MHz
+    LPC_TIM1->PR      = 11;         // TC clocks at 1MHz.
+    LPC_TIM1->MCR     = 2;          // Reset TCR to zero on match.
+    LPC_TIM1->MR0     = SAMPLE_PERIOD;
+    
+    // Prepare the GPDMA system.
+    conf = new MODDMA_Config;
+    conf
+     ->channelNum    ( MODDMA::Channel_0 )
+     ->srcMemAddr    ( (uint32_t)&LPC_GPIO0->FIOPIN )
+     ->dstMemAddr    ( (uint32_t)&buffer[0] )
+     ->transferSize  ( NUM_OF_SAMPLES )
+     ->transferType  ( MODDMA::g2m ) // pseudo transfer code MODDMA understands.
+     ->transferWidth ( MODDMA::word )
+     ->srcConn       ( MODDMA::MAT1_0 )
+     ->dmacSync      ( MODDMA::MAT1_0 ) 
+     ->attach_tc     ( TC0_callback )
+     ->attach_err    ( ERR0_callback )
+    ; // end conf.
+    
+    // Prepare configuration.
+    if (!dma.Setup( conf )) {
+        error("Doh!");
+    }
+    
+    // Enable GPDMA to be ready for the TIM1 "ticks".       
+    dma.Enable( conf );
+    
+    // Begin.
+    LPC_TIM1->TCR = 1;
+       
+    while (1) {          
+        led1 = !led1; // Show some sort of life.
+        
+        if (dmaTransferComplete) {
+            dmaTransferComplete = false;
+            for (int i = 0; i < NUM_OF_SAMPLES; i++) {
+                int val = (buffer[i] >> 4) & 0xF; 
+                pc.printf("Buffer index %d = 0x%x\n", i, val);
+            }
+            pc.printf("Done.\n");            
+        }
+    }       
+}
+
+// Configuration callback on TC
+void TC0_callback(void) {
+    
+    // Just show sample sequence grab complete.
+    led3 = !led3; 
+    
+    // Disable firing timer.
+    LPC_TIM1->TCR = 0;
+    
+    // Get configuration pointer.
+    MODDMA_Config *config = dma.getConfig();
+    
+    // Finish the DMA cycle by shutting down the channel.
+    dma.Disable( (MODDMA::CHANNELS)config->channelNum() );
+    
+    // Tell main() while(1) loop to print the results.
+    dmaTransferComplete = true;            
+    
+    // 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) {
+    error("Oh no! My Mbed EXPLODED! :( Only kidding, go find the problem");
+}