First commit of partly-working reflow oven controller.

humancontrol/Makefile

@@ -0,0 +1,3 @@
+# Makefile
+
+soldertimer: soldertimer.c

humancontrol/soldertimer.c

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+/* soldertimer.c */
+
+#include <stdio.h>
+#include <stdint.h>
+
+#include <stddef.h>
+#include <string.h>
+#include <time.h>
+
+
+typedef struct profile_line {
+    int32_t temperature; /* store degrees C * 4096 */
+    unsigned int time;
+} profile_line_t;
+
+typedef struct profile {
+    char name[21];
+    int32_t start_temp;
+    profile_line_t lines[6];
+} profile_t;
+
+#define DEGREES * 4096
+
+profile_t profile = {"Lead-free solder", 25 DEGREES, {
+	{ 150 DEGREES, 100 },
+	{ 200 DEGREES, 100 },
+	{ 250 DEGREES,  40 },
+	{ 250 DEGREES,  30 },
+	{ 100 DEGREES,  30 },
+	{ 0, 0 } }
+    };
+
+static int32_t expand_profile_temperature(uint8_t row)
+{
+    int32_t temp;
+
+    if (row > 1)
+	temp = profile.lines[row-2].temperature;
+    else
+	temp = profile.start_temp;
+
+    return temp;
+}
+
+static uint32_t profile_time(uint8_t line)
+{
+    uint32_t time = profile.lines[line].time;
+    return time;
+}
+
+static int finished;
+
+static int32_t temperature_at_time(uint32_t time) {
+    uint32_t time0, time1;
+    int32_t temp0, temp1;
+    uint8_t i;
+
+    temp1 = expand_profile_temperature(1);
+    time1 = 0;
+
+    i = 0;
+    do {
+	uint32_t ptime;
+	temp0 = temp1;
+	time0 = time1;
+	ptime = profile_time(i);
+	if (ptime > 0) {
+	    temp1 = expand_profile_temperature(2+i);
+	    time1 += ptime;
+	}
+	i++;
+	if (i >= 6)
+	    break;
+    } while (time > time1);
+
+    if (time > time1) {
+	finished = 1;
+	temp0 = temp1;
+	time0 = time1;
+	time1 += 60; /* Arbitrary number here */
+	temp1 = expand_profile_temperature(1);
+    }
+
+    if (time > time1)
+	return expand_profile_temperature(1);
+
+    return temp0 + (temp1 - temp0) * (int32_t)(time - time0) / (int32_t)(time1 - time0);
+}
+
+int main(void) {
+    time_t start;
+    time_t now;
+    time_t end;
+
+    finished = 0;
+
+    time(&start);
+
+    start = start + 10;
+
+    while (!finished) {
+	int32_t temp;
+	struct timespec interval = {0, 2000000};
+	time(&now);
+	if (now < start)
+	    temp = temperature_at_time(0);
+	else
+	    temp = temperature_at_time(now - start);
+	printf("\r%4ds       %.1f degrees", (int)(now - start), (double)temp / 4096);
+	fflush(stdout);
+	nanosleep(&interval, NULL);
+    }
+    printf("\n");
+}
+