Diff: main.cpp

Revision:

1:256d7a2f8391

Parent:

0:b0f98b83cb07

Child:

2:a57a5501152c

--- a/main.cpp	Thu Jul 03 19:55:29 2014 +0000
+++ b/main.cpp	Mon Jul 07 23:39:59 2014 +0000
@@ -1,46 +1,68 @@
-#include "mbed.h"
+#include "mbed.h" 
+ 
+int main() {
+    // NOTE: 24MHz is half the 48MHz clock rate.  The PWM registers
+    //       seem to only allow 24MHz at this point, so I'm matching
+    //       the SPI bus speed to be the same.
+    //
+    //       1/24MHz  =>  1/(24*10^6)  =>  41.6*10^-9 second period,
+    //       which means 41.6ns period and 20.8ns pulse width at
+    //       50% duty cycle (which seems to be right for the SPI clock
+    //       line as well as a reasonable choice for the PWM line).
 
 
-/////////////////////////////////////////////////
-//              SPI SETUP
-/////////////////////////////////////////////////
-// We are not using MISO, this is a one-way bus
-SPI device(SPI_MOSI, NC, SPI_SCK);
+    /////////////////////////////////////////////////
+    //              SPI SETUP
+    /////////////////////////////////////////////////
+    // We are not using MISO, this is a one-way bus
+    //SPI device(SPI_MOSI, NC, SPI_SCK);
 
-// Note: Polarity and phase are both 0 for the TC62D723FNG
-// For a graphical reminder on polarity and phase, visit:
-//     http://www.eetimes.com/document.asp?doc_id=1272534
-//
-device.format(16, 0);
-device.frequency(1000000); // 1 MHz
-/////////////////////////////////////////////////
+    // Note: Polarity and phase are both 0 for the TC62D723FNG
+    // For a graphical reminder on polarity and phase, visit:
+    //     http://www.eetimes.com/document.asp?doc_id=1272534
+    //
+    //device.format(16, 0);
+    //device.frequency(24000000); // 24 MHz
+    //device.frequency(1000000); // 1 MHz
+    /////////////////////////////////////////////////
 
 
 
-/////////////////////////////////////////////////
-//               PWMCLK
-/////////////////////////////////////////////////
-PwmOut pinPWMCLK(D9); // For Nucleo board, not for Redgarden board
-pinPWMCLK.write(0.5f); // Set to 50% duty cycle for testing
+    /////////////////////////////////////////////////
+    //               PWMCLK
+    /////////////////////////////////////////////////
+    //PwmOut pinPWMCLK(D9); // For Nucleo board, not for Redgarden board
+    //pinPWMCLK.write(0.5f); // Set to 50% duty cycle for testing
+
+
+    /////////////////////////////////////////////////
+    //              OTHER / DEBUG
+    /////////////////////////////////////////////////
+    /////////////////////////////////////////////////
+
+
 
 
-/////////////////////////////////////////////////
-//              OTHER / DEBUG
-/////////////////////////////////////////////////
-Serial pc(SERIAL_TX, SERIAL_RX);
-DigitalOut myled(LED1);
-/////////////////////////////////////////////////
- 
- 
-int main() {
-    int i = 0;
-    pc.printf("Hello World!\n");
+    printf("17:22\n");
+    //int i = 0;
     while(1) {
-        wait(1);
-        pc.printf("Alive for %d seconds.\n", i++);
-        myled = !myled;
-               
-        device.write(0x55);
-        device.write(0xE0);
+        wait_us(50);
+        
+        // S0 Command: Needs only SCK and SIN (which are SPI_SCK and SPI_MOSI respectively)
+        // This is because TRANS can be 0 for this command according to the datasheet
+        SPI data(SPI_MOSI, NC, SPI_SCK);
+        data.format(16, 0);
+        data.frequency(1000000); // 1 MHz
+        data.write(0xFF);
+    
+        // S1 Command: TRANS / "LATCH"
+        // The S1 command doesn't use SIN, but TRANS needs to be on for exactly
+        // three clock pulses.  The easiest way to do this is re-configuring
+        // the SPI bus to use the TRANS line as MOSI and sending 0x07.  If this
+        // doesn't work, we need to bitbang it.
+        SPI latch(PA_9, NC, SPI_SCK);
+        latch.format(16, 0);
+        latch.frequency(1000000); // 1 MHz        
+        latch.write(0x07); // Three clock pulses
     }
 }
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