Switch Case Error

[augustinemwendwa72]

Hey @gideonmaina , Under fetchSensorPMS(String& s), we are switching "len" which is predefined with value 0.
Also here: if (len == frame_len) { unless frame_len ==0 the function will not execute.

/*****************************************************************
 * read Plantronic PM sensor sensor values                       *
 *****************************************************************/

static void fetchSensorPMS(String& s) {
	char buffer;
	int value;
	int len = 0;
	int pm1_serial = 0;
	int pm10_serial = 0;
	int pm25_serial = 0;
	int checksum_is = 0;
	int checksum_should = 0;
	bool checksum_ok = false;
	int frame_len = 24;				// min. frame length

	debug_outln_verbose(FPSTR(DBG_TXT_START_READING), FPSTR(SENSORS_PMSx003));
	if (msSince(starttime) < (cfg::sending_intervall_ms - (WARMUPTIME_SDS_MS + READINGTIME_SDS_MS))) {
		if (is_PMS_running) {
			is_PMS_running = PMS_cmd(PmSensorCmd::Stop);
		}
	} else {
		if (! is_PMS_running) {
			is_PMS_running = PMS_cmd(PmSensorCmd::Start);
		}

		while (serialSDS.available() > 0) {
			buffer = serialSDS.read();
			debug_outln(String(len) + " - " + String(buffer, DEC) + " - " + String(buffer, HEX) + " - " + int(buffer) + " .", DEBUG_MAX_INFO);
//			"aa" = 170, "ab" = 171, "c0" = 192
			value = int(buffer);
			switch (len) {
			case 0:
				if (value != 66) {
					len = -1;
				};
				break;
			case 1:
				if (value != 77) {
					len = -1;
				};
				break;
			case 2:
				checksum_is = value;
				break;
			case 3:
				frame_len = value + 4;
				break;
			case 10:
				pm1_serial += ( value << 8);
				break;
			case 11:
				pm1_serial += value;
				break;
			case 12:
				pm25_serial = ( value << 8);
				break;
			case 13:
				pm25_serial += value;
				break;
			case 14:
				pm10_serial = ( value << 8);
				break;
			case 15:
				pm10_serial += value;
				break;
			case 22:
				if (frame_len == 24) {
					checksum_should = ( value << 8 );
				};
				break;
			case 23:
				if (frame_len == 24) {
					checksum_should += value;
				};
				break;
			case 30:
				checksum_should = ( value << 8 );
				break;
			case 31:
				checksum_should += value;
				break;
			}
			if ((len > 2) && (len < (frame_len - 2))) { checksum_is += value; }
			len++;
			if (len == frame_len) {
				debug_outln_verbose(FPSTR(DBG_TXT_CHECKSUM_IS), String(checksum_is + 143));
				debug_outln_verbose(FPSTR(DBG_TXT_CHECKSUM_SHOULD), String(checksum_should));
				if (checksum_should == (checksum_is + 143)) {
					checksum_ok = true;
					//debug_outln_info(F("Pms Sensor Is Okay----------------"));
				} else {
					len = 0;
					//debug_outln_info(F("Pms Sensor Is Not Okay----------------"));
				};

[gideonmaina]

@augustinemwendwa72 I will have an in-depth look at this. Please clarify which function won't run unless len==0 because I can only see the if statement.

From the look of things, the case statements are used to check which indices of the serial data we are at for it to do something e.g. extract distinct PM size values.

[gideonmaina]

@augustinemwendwa72 if you think this is a bug, could you post the expected behaviour or correct procedure that can be reproduced?