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authorChristian Franke <nobody@nowhere.ws>2013-12-10 06:01:52 (GMT)
committerChristian Franke <nobody@nowhere.ws>2013-12-10 06:01:52 (GMT)
commit4265af272a962ce1df1f6a975fdc8210f889760a (patch)
tree5aa10060c5c76ad99d5ab6e36fd81413d72a24cb
parentee3f9c98681127496101900d65d05c8520b16732 (diff)
Add some conversions from celsius to adc valuesHEADmaster
Luckily, this ATMega is grossly oversized, so we can just throw in floating point arithmetic.
-rw-r--r--command.c8
-rw-r--r--controller.c47
-rw-r--r--controller.h4
-rw-r--r--fit.py23
4 files changed, 71 insertions, 11 deletions
diff --git a/command.c b/command.c
index 7d8c515..09b91ec 100644
--- a/command.c
+++ b/command.c
@@ -14,7 +14,7 @@ static void handle_set(char *buffer, uint16_t len)
const char *success_msg = "OK Temperature set.\r\n";
const char *input;
char *endptr;
- long temperature;
+ double temperature;
if (len < 2) {
serial_send(error_msg, strlen(error_msg), 0);
@@ -22,7 +22,7 @@ static void handle_set(char *buffer, uint16_t len)
}
input = buffer + 1;
- temperature = strtol(input, &endptr, 10);
+ temperature = strtod(input, &endptr);
if (input[0] == '\r' || input[0] == '\n' ||
(endptr[0] != '\r' && endptr[0] != '\n')) {
serial_send(error_msg, strlen(error_msg), 0);
@@ -48,8 +48,10 @@ static void handle_off(char *buffer, uint16_t len)
static void handle_get(char *buffer, uint16_t len)
{
char response[128];
+ long temp = 10 * controller_get();
- snprintf(response, sizeof(response), "OK t=%ld\r\n", controller_get());
+ /* printf won't print doubles on avr */
+ snprintf(response, sizeof(response), "OK t=%ld.%ld\r\n", temp/10, temp%10);
serial_send(response, strlen(response), 0);
}
diff --git a/controller.c b/controller.c
index bde2cac..6dee4da 100644
--- a/controller.c
+++ b/controller.c
@@ -1,9 +1,13 @@
#include <avr/io.h>
#include <avr/interrupt.h>
+#include <math.h>
+#include <stdio.h>
+#include <string.h>
#include "controller.h"
#include "bridge.h"
+#include "serial.h"
static void adc_init(void)
{
@@ -40,20 +44,43 @@ void controller_init(void)
timer_init();
}
-int controller_set(long target)
+static long celsius_to_adc(double target_temp)
{
- if (target < 50 || target > 974)
+ long rv;
+
+ rv = 1203.59290 * exp(-0.0686201496 * target_temp) + 413.59437;
+ if (rv > 1017)
+ return 1017;
+ if (rv < 450)
+ return 450;
+ return rv;
+}
+
+static double adc_to_celsius(long adc)
+{
+ double rv;
+
+ rv = adc - 413.59437;
+ rv /= 1203.59290;
+ rv = log(rv);
+ rv /= -0.0686201496;
+ return rv;
+}
+
+int controller_set(double target)
+{
+ if (target < 8.0 || target > 42.0)
return 1;
- controller_target_temp = target;
+ controller_target_temp = celsius_to_adc(target);
controller_num_iterations = 1;
controller_active = 1;
return 0;
}
-long controller_get(void)
+double controller_get(void)
{
- return controller_measured_temp;
+ return adc_to_celsius(controller_measured_temp);
}
void controller_off(void)
@@ -82,8 +109,16 @@ ISR(ADC_vect)
return;
controller_num_iterations--;
- if (controller_num_iterations)
+ if (controller_num_iterations) {
+#if 0
+ char buffer[128];
+ snprintf(buffer, sizeof(buffer), "DEBUG adc==%ld adc_target=%ld\r\n",
+ (long int)controller_measured_temp,
+ controller_target_temp);
+ serial_send(buffer, strlen(buffer), 0);
+#endif
return;
+ }
controller_num_iterations = 60;
diff --git a/controller.h b/controller.h
index 0b65a73..70e7f30 100644
--- a/controller.h
+++ b/controller.h
@@ -2,8 +2,8 @@
#define CONTROLLER_H
void controller_init(void);
-int controller_set(long target);
-long controller_get(void);
+int controller_set(double target);
+double controller_get(void);
void controller_off(void);
#endif
diff --git a/fit.py b/fit.py
new file mode 100644
index 0000000..1ecee1f
--- /dev/null
+++ b/fit.py
@@ -0,0 +1,23 @@
+from scipy.optimize import curve_fit
+import numpy
+import matplotlib.pyplot as pyplot
+
+
+data_x = numpy.array([ 10, 13, 17, 21, 24, 31, 36, 41 ])
+data_y = numpy.array([ 1017, 898, 810, 715, 620, 547, 510, 500 ])
+
+def func(x, a, b, c):
+ return a * numpy.exp(-b*x)-c
+
+popt, pcov = curve_fit(func, data_x, data_y, maxfev=5000)
+trial_x = numpy.linspace(0, 50, 200)
+trial_y = func(trial_x, *popt)
+
+print popt
+
+pyplot.figure()
+pyplot.plot(data_x, data_y, 'ro', label='Data')
+pyplot.plot(trial_x, trial_y, 'b-', label="Exp Fit")
+pyplot.legend()
+pyplot.show()
+