Diff: main.cpp

Revision:

0:2afedb12bdfd

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/main.cpp	Fri Aug 12 15:27:31 2011 +0000
@@ -0,0 +1,175 @@
+#include "mbed.h"
+
+/*
+**************************************************************************************
+AD5627.  Dual 12-bit DAC with i2C interface and external reference pin.
+(The AD56x7R have an internal reference). Power supply: 2.7V to 5.5V.
+
+If needed, the two DACs can be updated simultaneously by LDAC (pin 4)or by software.
+
+Wiring:
+pin 3 (GND) to ground. pin 9 (Vdd) to 3.3V.
+pin 10 (Vref) to 3.3V, pin 6 (ADDR) to 3.3V (A1=0, A0=0).
+4.7k pull-up resistors on pins 8 and 7 (SDA, SCL)(to mBed's pins 9 and 10).
+pin 4 (LDAC) and pin 5 (CLR) to mBed's digital output pins 11 and 12.
+
+Attach voltmeter to ground and Vout A (pin 1)  or  Vout B (pin 2).
+
+Command byte: 0 S C2 C1 C0 A2 A1 A0. s=1: multiple block write,  s=0: one block write.
+
+Commands C2 C1 C0:
+000: Write to input register.
+001: Update DAC register.
+010: Write to input register n, update all (software LDAC).
+011: Write and update DAC channel n.
+100: Power up / power down.
+101: Reset.
+110: LDAC register setup.
+111: Internal reference setup (on/off).
+
+DAC address command A2 A1 A0:
+000: DAC A.
+001: DAC B.
+111: Both DACs.
+
+
+Author: Lluis Nadal. August 2011.
+**************************************************************************************
+*/
+
+I2C i2c(p9, p10); // SDA, SCL
+Serial pc(USBTX, USBRX);
+DigitalOut LDAC (p11);
+DigitalOut CLR (p12);
+
+DigitalOut L1(LED1);
+DigitalOut L2(LED2);
+DigitalOut L3(LED3);
+DigitalOut L4(LED4);
+
+const int addr_R = 0x19; // Address to read
+const int addr_W = 0x18; // Address to write
+
+const int CA1 = 0x18; // Command: DAC A one block write
+const int CB1 = 0x19; // Command: DAC B one block write
+const int CA2 = 0x58; // Command: DAC A multiple block write
+const int CB2 = 0x59; // Command: DAC B multiple block write
+const int CA3 = 0x00; // Command: DAC A using LDAC to update.
+const int CB3 = 0x01; // Command: DAC B using LDAC to update.
+
+
+void write_A(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);
+    L = n<<4 & 0xF0;
+    H = n>>4;
+    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(CA1);    // Write command
+    i2c.write(H);      // Write high byte
+    i2c.write(L);      // Write low byte
+    i2c.stop();
+}
+
+
+void write_B(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);
+    L = n<<4 & 0xF0;
+    H = n>>4;
+    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(CB1);    // Write command
+    i2c.write(H);      // Write high byte
+    i2c.write(L);      // Write low byte
+    i2c.stop();
+}
+
+void write_A_LDAC(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);
+    L = n<<4 & 0xF0;
+    H = n>>4;
+    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(CA3);    // Write command
+    i2c.write(H);      // Write high byte
+    i2c.write(L);      // Write low byte
+    i2c.stop();
+}
+
+void write_B_LDAC(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);
+    L = n<<4 & 0xF0;
+    H = n>>4;
+    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(CB3);    // Write command
+    i2c.write(H);      // Write high byte
+    i2c.write(L);      // Write low byte
+    i2c.stop();
+}
+
+
+int main() {
+    L1 = 0;
+    i2c.frequency(100000);
+
+    // Pulsing this pin low allows any or all DAC registers to be updated if they have new data.
+    LDAC = 0;
+
+    CLR = 0; // Outputs the two DACs to 0V.
+    wait(5);
+    CLR = 1;
+    L1 = 1;
+
+    // DAC A one block write
+    write_A(2.537);
+    wait(5);
+    
+    // DAC A one block write
+    write_A(1.777);
+    L2 = 1;
+    wait(5);
+
+    // DAC B one block write
+    write_B(0.666);
+    wait(5);
+    
+    // DAC B one block write
+    write_B(3.000);
+    wait(5);
+
+
+    // Using LDAC pin
+    LDAC = 1;
+    write_A_LDAC(1.000); // DAC register A is not updated
+    write_B_LDAC(1.500); // DAC register B is not updated
+    L3 = 1;
+    wait(5);
+
+    LDAC = 0; // DAC registers A and B are updated simultaneously
+    L4 = 1;
+
+}