-DataPoint * GetData(int sensor_id, DataPoint * d)
-{
- //TODO: We should ensure the time is *never* allowed to change on the server if we use gettimeofday
- // Another way people might think of getting the time is to count CPU cycles with clock()
- // But this will not work because a) CPU clock speed may change on some devices (RPi?) and b) It counts cycles used by all threads
- gettimeofday(&(d->time_stamp), NULL);
+#include "gpio.h"
+
+/**
+ * Read a DataPoint from a Sensor; block until value is read
+ * @param id - The ID of the sensor
+ * @param d - DataPoint to set
+ * @returns True if the DataPoint was different from the most recently recorded.
+ */
+bool Sensor_Read(Sensor * s, DataPoint * d)
+{
- switch (sensor_id)
+ // Set time stamp
+ struct timeval t;
+ gettimeofday(&t, NULL);
+ d->time_stamp = TIMEVAL_DIFF(t, g_options.start_time);
+
+ // Read value based on Sensor Id
+ switch (s->id)
{
- //TODO: test buffer size on actual hardware
- // maybe map the sensor path to an array/structure that can be looked up via sensor_id?
- // not sure about the best place to do unit conversions, especially for nonlinear sensors
- case SENSOR_TEST0:
+ case ANALOG_TEST0:
+ d->value = ADCRead(0); //ADC #0 on the Beaglebone
+ break;
+ case ANALOG_TEST1:
{
- int sensor = open("/sys/devices/platform/tsc/ain0", O_RDONLY); //need unique path for each sensor ADC, check path in documentation
- char buffer[128]; //ADCs on Beaglebone are 12 bits?
- int read = read(sensor, buffer, sizeof(buffer);
- if (read != -1) {
- buffer[read] = NULL; //string returned by read is not null terminated
- int value = atoi(buffer);
- double convert = (value/4096) * 1800; //sample conversion from ADC input to 'true value'
- d->value = convert;
- lseek(sensor, 0, 0); //after read string must be rewound to start of file using lseek
- }
- else {
- perror("Failed to get value from sensor");
- }
- close(sensor);
+ d->value = ADCRead(1);
break;
}
- case SENSOR_TEST1:
- int sensor = open("/sys/devices/platform/tsc/ain1", O_RDONLY);
- char buffer[128];
- int read = read(sensor, buffer, sizeof(buffer);
- if (read != -1) {
- buffer[read] = NULL;
- int value = atoi(buffer);
- double convert = (value/4096) * 1800;
- d->value = convert;
- lseek(sensor, 0, 0);
- }
- else {
- perror("Failed to get value from sensor");
- }
- close(sensor);
- break;
+ case ANALOG_FAIL0:
+ d->value = (double)(rand() % 6) * -( rand() % 2) / ( rand() % 100 + 1);
+ //Gives a value between -5 and 5
break;
- }
- //TODO: think about a better way to address individual pins
- // i.e. pass an int to a separate function that builds the correct filename
- // doesn't really matter if the pins we're using are fixed though
case DIGITAL_TEST0:
- int fd = open("/sys/class/gpio/gpio17/value", O_RDONLY) //again need the right addresses for each pin
- char ch; //just one character for binary info
- lseek(fd, 0, SEEK_SET);
- int read = read(fd, &ch, sizeof(ch);
- if (read != -1) {
- if (ch != '0') {
- d->value = 1;
- }
- else {
- d->value = 0;
- }
- }
- else {
- perror("Failed to get value from pin");
- }
+ d->value = pinRead(0); //replace 0 with correct pin number
break;
case DIGITAL_TEST1:
- int fd = open("/sys/class/gpio/gpio23/value", O_RDONLY)
- char ch;
- lseek(fd, 0, SEEK_SET);
- int read = read(fd, &ch, sizeof(ch);
- if (read != -1) {
- if (ch != '0') {
- d->value = 1;
- }
- else {
- d->value = 0;
- }
- }
- else {
- perror("Failed to get value from pin");
- }
+ d->value = pinRead(1); //replace 1 with correct pin number
+ break;
+ case DIGITAL_FAIL0:
+ if( rand() % 100 > 98)
+ d->value = 2;
+ d->value = rand() % 2;
+ //Gives 0 or 1 or a 2 every 1/100 times
break;
default:
- Fatal("Unknown sensor id: %d", sensor_id);
+ Fatal("Unknown sensor id: %d", s->id);
break;
}
usleep(100000); // simulate delay in sensor polling
- return d;
+ // Perform sanity check based on Sensor's ID and the DataPoint
+ Sensor_CheckData(s->id, d->value);
+
+ // Update latest DataPoint if necessary
+ bool result = (d->value != s->newest_data.value);
+ if (result)
+ {
+ s->newest_data.time_stamp = d->time_stamp;
+ s->newest_data.value = d->value;
+ }
+ return result;
}
\ No newline at end of file
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