Implement serial command parser with floating point support

src/common.h

@@ -5,6 +5,7 @@
 #include "common/types.h"
 #include "common/watchdog.h"
 #include "common/memory.h"
+#include "common/parser.h"
 
 #include <stddef.h>
 #include <stdarg.h>

src/common/parser.c

@@ -0,0 +1,72 @@
+#include "common.h"
+
+#include <stdlib.h>
+#include <ctype.h>
+#include <errno.h>
+
+#define CMD_MAX_LEN 128
+
+// TODO: Write documentation.
+// TODO: Implement start and stop commands.
+// TODO: Reset command buffer on timeout?
+
+static char cmdbuf[CMD_MAX_LEN + 1];
+static char *tail = cmdbuf + CMD_MAX_LEN - 1;
+static char *head = cmdbuf;
+
+static bool ParseLine(cmd_t *out);
+
+bool CMD_Parse(char ch, cmd_t *out)
+{
+	bool is_valid;
+
+	if (ch == '\n' || ch == '\r') {
+		is_valid = ParseLine(out);
+		tail = cmdbuf + CMD_MAX_LEN - 1; 
+		head = cmdbuf;
+		return is_valid;
+	}
+
+	if (head < tail) {
+		*head++ = ch;
+		*head = '\0';
+	}
+
+	return false;
+}
+
+static bool ParseLine(cmd_t *out)
+{
+	head = cmdbuf;
+
+	// Command SET <float> <float>
+	if (tolower(head[0] == 's')) {
+		if ((tolower(head[1]) != 'e') ||
+		    (tolower(head[2]) != 't')) {
+			return false;
+		}
+
+		out->type = T_SET;
+		head += 3;
+
+		// Parse <float> arguments
+		for (int i = 0; i < 2; i++) {
+			errno = 0;
+
+			// Try converting string to floating point
+			// Skips whitespace and moves tail pointer
+			out->args[i] = (float) strtod(head, &tail);
+
+			if ((errno == ERANGE) ||
+			    (out->args[i] == 0 && head == tail)) {
+				return false; // Conversion failed
+			}
+
+			head = tail;
+		}
+
+		return true;
+	}
+
+	return false;
+}

src/common/parser.h

@@ -0,0 +1,18 @@
+#ifndef MAD_CORE_COMMON_PARSER
+#define MAD_CORE_COMMON_PARSER
+
+#include "common/types.h"
+
+// Command types
+#define T_SET  0
+
+struct cmd_s {
+	int    type;
+	float  args[2];
+};
+
+typedef struct cmd_s cmd_t;
+
+bool CMD_Parse(char ch, cmd_t *out);
+
+#endif // MAD_CORE_COMMON_PARSER

src/main.c

@@ -7,14 +7,13 @@
 #include <avr/interrupt.h>
 
 // TODO: Config header for chip specifics like EEPROM size.
-// TODO: Make sure wear leveling resets memory correctly.
+// TODO: Fix huge serial command input triggering watchdog.
+// TODO: Only update EEPROM if value differs from previous.
+// TODO: Check thermistor conversion results /w thermometer.
 // TODO: Implement primary state machine for update loop.
 // TODO: Migrate to ATMega 1284P-PU for 2nd 16-bit timer.
-// TODO: Check thermistor conversion results /w thermometer.
-// TODO: Implement optional CRC8 sensor measurement check.
 // TODO: Use 18.432MHz quarz crystal, burn required fuses.
-// TODO: Make sure nothing breaks with negative temperatures.
-// TODO: Write an improved command parser (low priority).
+// TODO: Implement optional CRC8 sensor measurement check.
 // TODO: Proper error handling and recovery (after testing).
 // TODO: Check why the MCUCSR EXTRF reset flag is set.
 
@@ -30,6 +29,10 @@ static enum state_e state;
 static word temp, temp_target;
 static word dewp, dewp_target;
 
+static int   Init(void);
+static void  Update(void);
+static void  UpdateSensors(void);
+
 static int Init(void)
 {
 	mem_block_t mem;
@@ -82,8 +85,11 @@ static int Init(void)
 
 	if (MEM_Read(&mem) == 0) {
 		Info("Found persistent configuration in EEPROM!");
-		Info("Setting targets TEMP='%.2f', DEWP='%.2f'.",
+		Info("Setting targets TEMP='%.2fC', DEWP='%.2fC'.",
 			mem.temp, mem.dewp);
+
+		temp_target = mem.temp;
+		dewp_target = mem.dewp;
 	}
 
 	// There is a possiblity to use interrupt signals
@@ -130,6 +136,50 @@ static int Init(void)
 }
 
 static void Update(void)
+{
+	char ch;
+	cmd_t cmd;
+	mem_block_t mem;
+
+	// Parse serial commands
+	while ((ch = USART_Getc()) >= 0) {
+		if (!CMD_Parse(ch, &cmd)) {
+			WDT_Reset();
+			continue;
+		}
+		switch(cmd.type) {
+		case T_SET: // Configure new persistent target
+			Info("Setting new target TEMP='%.2fC'...", cmd.args[0]);
+			Info("Setting new target DEWP='%.2fC'...", cmd.args[1]);
+			mem.temp = temp_target = cmd.args[0];
+			mem.dewp = dewp_target = cmd.args[1];
+			MEM_Write(&mem);
+			return;
+		}
+	}
+
+	// Poll sensor values
+	UpdateSensors();
+
+	// Handle state
+	switch (state) {
+	case S_IDLE:
+		break;
+	case S_HEAT_UP:
+		break;
+	case S_COOL_DOWN:
+		break;
+	case S_DEHUMIDIFY:
+		break;
+	}
+
+	UNUSED(temp);
+	UNUSED(dewp);
+	UNUSED(temp_target);
+	UNUSED(dewp_target);
+}
+
+static void UpdateSensors(void)
 {
 	float t[6], rh[3], dp[3];
 	float t_avg, rh_avg, dp_avg;
@@ -167,25 +217,6 @@ static void Update(void)
 	Info("T2=%.2fC, RH2=%.2f%%, NT2=%.2fC, DEW2=%.2fC", t[1], rh[1], t[4], dp[1]);
 	Info("T3=%.2fC, RH3=%.2f%%, NT3=%.2fC, DEW3=%.2fC", t[2], rh[2], t[5], dp[2]);
 	Info("T_AVG=%.2fC, RH_AVG=%.2f%%, DP_AVG=%.2fC", t_avg, rh_avg, dp_avg);
-
-	// TODO: Implement state machine
-	// TODO: Handle serial commands
-
-	switch (state) {
-	case S_IDLE:
-		break;
-	case S_HEAT_UP:
-		break;
-	case S_COOL_DOWN:
-		break;
-	case S_DEHUMIDIFY:
-		break;
-	}
-
-	UNUSED(temp);
-	UNUSED(dewp);
-	UNUSED(temp_target);
-	UNUSED(dewp_target);
 }
 
 int main(void)