Diff: main.cpp

Revision:

0:afa6a5e2d11a

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/main.cpp	Wed Jul 27 19:35:48 2016 +0000
@@ -0,0 +1,132 @@
+#include "mbed.h"
+
+DigitalOut myled(LED1);
+DigitalOut convst(p18);     // Conversion Start (active low)
+DigitalOut cs(p16);         // Chip Select (active low)
+DigitalIn  eoc(p20);        // End of Conversion (active low)
+SPI spi(p11, p12, p13);     // mosi, miso, sclk
+Serial pc(USBTX, USBRX);    // tx, rx
+
+#define AIN0  0u
+#define AIN1  1u
+#define AIN2  2u
+#define AIN3  3u
+#define AIN4  4u
+#define AIN5  5u
+#define AIN6  6u
+#define AIN7  7u
+#define AIN8  8u
+#define AIN9  9u
+#define AIN10 10u
+#define AIN11 11u
+#define AIN12 12u
+#define AIN13 13u
+#define AIN14 14u
+#define AIN15 15u
+
+#define SCAN_TO_N               0u // Scans channels 0 through N.
+#define SCAN_N_TO               1u // Scans channels N through the highest numbered channel.
+#define SCAN_N_AVG              2u // Scans channel N repeatedly. The averaging register sets the number of results.
+#define SCAN_OFF                3u // No scan. Converts channel N once only
+
+#define CLKSEL_INT_INT_CNVST    0u // Internal clock, internal aqcuisition, convst
+#define CLKSEL_INT_EXT_CNVST    1u // Internal clock, external aqcuisition convst, convst
+#define CLKSEL_INT_INT_ADC      2u // Internal clock, internal aqcuisition, extra channel
+#define CLKSEL_EXT_EXT_ADC      3u // External clock, external aqcuisition sclk, extra channel
+
+#define REFSEL_INT_SLEEP        0u // Reference off after scan; need wake-up delay
+#define REFSEL_EXT              1u // Reference off; no wake-up delay.
+#define REFSEL_INT_NOSLEEP      2u // Reference always on; no wake-up delay.
+#define REFSEL_RESERVED         3u // Reserved. Do not use.
+
+#define NAVG_4                  0u // Performs four conversions and returns the average for each requested result.
+#define NAVG_8                  1u // Performs eight conversions and returns the average for each requested result.
+#define NAVG_16                 2u // Performs 16 conversions and returns the average for each requested result.
+#define NAVG_32                 3u // Performs 32 conversions and returns the average for each requested result.
+                            
+#define NSCAN_4                 0u // Scans channel N and returns four results.
+#define NSCAN_8                 1u // Scans channel N and returns eight results.
+#define NSCAN_12                2u // Scans channel N and returns 12 results.
+#define NSCAN_16                3u // Scans channel N and returns 16 results.
+
+uint8_t compile_reset(bool fifo_only){
+    if(fifo_only)
+        return 0x18;
+    else
+        return 0x10;
+}
+
+uint8_t compile_conversion(uint8_t ch, uint8_t scan){
+    return 0x80 | ((ch&0xF)<<3)|((scan&0x3)<<1);
+}
+
+uint8_t compile_setup(uint8_t clk, uint8_t ref){
+    return 0x40 | ((clk&0x3)<<4)|((ref&0x3)<<2);
+}
+
+uint8_t compile_avg(bool avgon, uint8_t navg, uint8_t nscan){
+    uint8_t y = 0x20;
+    if(avgon) y |= 0x10;
+    y |= ((navg&0x3)<<2)|(nscan&0x3);
+    return y;
+}
+
+int main() {
+    int data[4];
+    convst = 1;
+    cs = 1;
+
+    // The max11626 uses normal 8 bit spi for the registers.
+    // However, >8 bit reads can be used to read the data (mosi would be 0 during read).
+    spi.format(8,3);
+    spi.frequency(10000);
+    
+    // MAX11626 addressing.
+    // Addressing is performed by the leading zeros.
+    // - no leading zero (0x80) would be the conversion register.
+    // - one leading zeros (0x40) would be the setup register.
+    // - two leading zeros (0x20) would be the averaging register.
+    // - 3 leading zeros (0x10) would be the reset register.
+    // Transfers are MSB first.
+    // Reading data is always safe when you set MOSI to 0.
+
+    // Let the scope settle after reset
+    wait(1);
+
+    while(1) {
+        // Write reset full.
+        cs = 0;
+        spi.write(compile_reset(0)); 
+        cs = 1;
+        
+        wait_us(100);
+        
+        // Write conversion
+        cs = 0;
+        spi.write(compile_conversion(AIN3, SCAN_TO_N)); 
+        cs = 1;
+
+        wait_us(100);
+        
+        convst = 0;
+        wait_us(100);
+        convst = 1;
+        
+        wait_us(100);
+        
+        cs = 0;
+        // Read 4
+        for(int i=0; i<4; i++){
+            data[i] = 0;
+            data[i] = spi.write(0);
+            data[i] <<= 8;
+            data[i] |= spi.write(0);
+        }
+        cs = 1;
+        
+        pc.printf("%05d, %05d, %05d, %05d\n",data[0],data[1],data[2],data[3]);
+        wait(0.2);
+        
+        myled = !myled;
+    }
+}