Diff: main.cpp

Revision:

0:07ef132e042b

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/main.cpp	Thu Aug 11 07:03:33 2011 +0000
@@ -0,0 +1,103 @@
+#include "mbed.h"
+
+/*
+***************************************************************************************
+MCP4725_Test. 12-bit DAC with i2C interface.
+pin 3(Vdd)= 3.3V. pin 6(A0) = 0. pin 4(SDA) and pin 5(SCL): 4,7k pull-up resistors.
+Attach multimeter to pin1(Vout) and ground.
+Author: Lluis Nadal. August 2011.
+***************************************************************************************
+*/
+
+I2C i2c(p9, p10); // SDA, SCL
+Serial pc(USBTX, USBRX);
+
+const int addr_R = 0xC1; // Address to read
+const int addr_W = 0xC0; // Address to write
+
+void write(float v) { // 0 < v < 3.3 V
+    char H;      // High byte
+    char L;      // Low byte
+    int n;
+    n = (int)(v*4096/3.3);
+    pc.printf(" n= %d\r\n", n);
+    H = n>>4;
+    L = (n<<4 & 0xF0);
+    pc.printf(" (H, L)=(%d, %d)\r\n", H, L);
+    pc.printf("\r\n");
+    i2c.start();
+    i2c.write(addr_W); // Write address to write
+    i2c.write(0x40);   // Write command
+    i2c.write(H);      // Write high byte
+    i2c.write(L);      // Write low byte
+    i2c.stop();
+}
+
+void write_fast(float v) {
+    char H=0;
+    char L=0;
+    int n;
+    n = (int)(v*4096/3.3);
+    pc.printf(" n= %d\r\n", n);
+    L = n & 0xFF;
+    H = (n>>8) & 0x0F;
+    pc.printf(" (H, L)=(%d, %d)\r\n", H, L);
+    pc.printf("\r\n");
+    i2c.start();
+    i2c.write(addr_W);
+    i2c.write(H);
+    i2c.write(L);
+    i2c.stop();
+}
+
+void write_EEPROM(float v) { // 0 < v < 3.3 V
+    char H;      // High byte
+    char L;      // Low byte
+    int n;
+    n = (int)(v*4096/3.3);
+    pc.printf(" n= %d\r\n", n);
+    H = n>>4;
+    L = (n<<4 & 0xF0);
+    pc.printf(" (H, L)=(%d, %d)\r\n", H, L);
+    pc.printf("\r\n");
+    i2c.start();
+    i2c.write(addr_W); // Write address to write
+    i2c.write(0x60);   // Write command
+    i2c.write(H);      // Write high byte
+    i2c.write(L);      // Write low byte
+    i2c.stop();
+}
+
+
+int main() {
+
+    i2c.frequency(100000);
+
+    // On power-up the voltage is the data stored in EEPROM.
+    pc.printf(" On power-up the voltage is the data stored in EEPROM.\r\n");
+    pc.printf("\r\n");
+    wait(5);
+
+    // Write to DAC register in normal mode
+    pc.printf(" Normal mode\r\n");
+    write(1.3585);
+    wait(5);
+    write(2.6758);
+    wait(5);
+    write(1.7554);
+    wait(5);
+
+    // Write to DAC register in fast mode
+    pc.printf(" Fast mode\r\n");
+    write_fast(1.3585);
+    wait(5);
+    write_fast(2.6758);
+    wait(5);
+    write_fast(1.7554);
+
+    // Write to EEPROM
+    pc.printf(" Write to EEPROM\r\n");
+    write_EEPROM(0.5); // On power_up the voltage will be 0.5V.
+
+
+}
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