Thomas Murphy
An example demonstrating the usage of the default FXOS8700CQ firmware configuration by Thomas Murphy. Uses interrupts to control flow and to cue access to the peripheral.
Configure your serial terminal as 115200, 8, none, 1, Xon/Xoff. If you don't set flow control, your terminal may spit out large piles of junk much more slowly that it was supposed to receive data.
Revision 0:6c6060a8a2f6, committed 2014-05-28
- Comitter:
- trm
- Date:
- Wed May 28 17:32:41 2014 +0000
- Commit message:
- Initial commit of complete example of using FXOS8700CQ firmware by Thomas Murphy.
Changed in this revision
--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/FXOS8700CQ.lib Wed May 28 17:32:41 2014 +0000 @@ -0,0 +1,1 @@ +http://mbed.org/users/trm/code/FXOS8700CQ/#4c2f8a3549a9
--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/main.cpp Wed May 28 17:32:41 2014 +0000
@@ -0,0 +1,123 @@
+#include "mbed.h"
+#include "FXOS8700CQ.h"
+
+#define DATA_RECORD_TIME_MS 1000
+
+Serial pc(USBTX, USBRX); // Primary output to demonstrate library
+
+// Pin names for FRDM-K64F
+FXOS8700CQ fxos(PTE25, PTE24, FXOS8700CQ_SLAVE_ADDR1); // SDA, SCL, (addr << 1)
+
+DigitalOut green(LED_GREEN); // waiting light
+DigitalOut blue(LED_BLUE); // collection-in-progress light
+DigitalOut red(LED_RED); // completed/error ligt
+
+Timer t; // Microsecond timer, 32 bit int, maximum count of ~30 minutes
+InterruptIn fxos_int1(PTC6); // unused, common with SW2 on FRDM-K64F
+InterruptIn fxos_int2(PTC13); // should just be the Data-Ready interrupt
+InterruptIn start_sw(PTA4); // switch SW3
+
+// Interrupt status flags and data
+bool fxos_int1_triggered = false;
+bool fxos_int2_triggered = false;
+uint32_t us_ellapsed = 0;
+bool start_sw_triggered = false;
+
+// Storage for the data from the sensor
+SRAWDATA accel_data;
+SRAWDATA magn_data;
+
+void trigger_fxos_int1(void)
+{
+ fxos_int1_triggered = true;
+}
+
+void trigger_fxos_int2(void)
+{
+ fxos_int2_triggered = true;
+ us_ellapsed = t.read_us();
+}
+
+void trigger_start_sw(void)
+{
+ start_sw_triggered = true;
+}
+
+void print_reading()
+{
+ pc.printf("%d A X:%5d,Y:%5d,Z:%5d M X:%5d,Y:%5d,Z:%5d\r\n",
+ us_ellapsed,
+ accel_data.x, accel_data.y, accel_data.z,
+ magn_data.x, magn_data.y, magn_data.z);
+}
+
+int main(void)
+{
+ // Setup
+ t.reset();
+ pc.baud(115200); // Print quickly! 200Hz x line of output data!
+
+ // Lights off (FRDM-K64F has active-low LEDs)
+ green.write(1);
+ red.write(1);
+ blue.write(1);
+
+ // Diagnostic printing of the FXOS WHOAMI register value
+ printf("\r\n\nFXOS8700Q Who Am I= %X\r\n", fxos.get_whoami());
+
+ // Iterrupt for active-low interrupt line from FXOS
+ // Configured with only one interrupt on INT2 signaling Data-Ready
+ fxos_int2.fall(&trigger_fxos_int2);
+ fxos.enable();
+
+ // Interrupt for SW3 button-down state
+ start_sw.mode(PullUp); // Since the FRDM-K64F doesn't have its SW2/SW3 pull-ups populated
+ start_sw.fall(&trigger_start_sw);
+
+ green.write(0); // ready-green on
+
+ // Example data printing
+ fxos.get_data(&accel_data, &magn_data);
+ print_reading();
+
+ pc.printf("Waiting for data collection trigger on SW3\r\n");
+
+ while(true) {
+ if(start_sw_triggered) {
+ break;
+ }
+ wait_ms(50); // just to slow the loop, fast enough for UX
+ }
+
+ green.write(1); // ready-green off
+ blue.write(0); // working-blue on
+
+ pc.printf("Started data collection. Accelerometer at max %dg.\r\n",
+ fxos.get_accel_scale());
+
+ fxos.get_data(&accel_data, &magn_data); // clear interrupt from device
+ fxos_int2_triggered = false; // un-trigger
+
+ t.start(); // start timer and enter collection loop
+ while (t.read_ms() <= DATA_RECORD_TIME_MS) {
+
+ if(fxos_int2_triggered) {
+ fxos_int2_triggered = false; // un-trigger
+ fxos.get_data(&accel_data, &magn_data);
+ print_reading(); // outpouring of data !!
+ }
+
+ // Continuous polling of interrupt status is not efficient, but...
+ wait_us(500); // 1/10th the period of the 200Hz sample rate
+ }
+
+ blue.write(1); // working-blue off
+ red.write(0); // complete-red on
+
+ pc.printf("Done. Reset to repeat.\r\n");
+
+ while(true) {
+ pc.putc('.'); // idle dots
+ wait(1.0);
+ }
+}
\ No newline at end of file
--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/mbed.bld Wed May 28 17:32:41 2014 +0000 @@ -0,0 +1,1 @@ +http://mbed.org/users/mbed_official/code/mbed/builds/0b3ab51c8877 \ No newline at end of file