diff --git a/main.c b/main.c
index 83e895a..4a5e0d2 100644
--- a/main.c
+++ b/main.c
@@ -1,4 +1,5 @@
 #include <stdio.h>
+#include <string.h>
 #include <stdlib.h>
 #include "scpi_parser.h"
 
@@ -15,7 +16,7 @@ const SCPI_command_t scpi_cmd_lang[4] = {
 		.callback = cmd_aIDNq_cb
 	},
 	{
-		.level_cnt = 2, .levels = {"APPLy", "SINe"},
+		.level_cnt = 3, .levels = {"APPLy", "SINe"},
 		.param_cnt = 3, .params = {SCPI_DT_INT, SCPI_DT_FLOAT, SCPI_DT_FLOAT},
 		.callback = cmd_APPL_SIN_cb
 	},
@@ -57,9 +58,15 @@ void cmd_FREQ_cb(const SCPI_argval_t *args)
 
 
 
-int main(int argc, const char**argv)
+int main()
 {
-	const char *inp = argv[1];
+	//const char *inp = "*IDN?\n";
+	const char *inp = "FREQ 123\n";
+
+	for(int i=0;i<strlen(inp); i++) {
+		scpi_handle_byte(inp[i]);
+	}
+
 
 //	printf("%d\n", char_equals_ci('a','A'));
 //	printf("%d\n", char_equals_ci('z','z'));
diff --git a/main.elf b/main.elf
index e79e323..0cc4236 100755
Binary files a/main.elf and b/main.elf differ
diff --git a/scpi_parser.c b/scpi_parser.c
index bb943b4..135b1c4 100644
--- a/scpi_parser.c
+++ b/scpi_parser.c
@@ -8,10 +8,14 @@
 
 typedef enum {
 	PARS_COMMAND,
-	PARS_ARG, // collect generic arg, terminated with comma or newline. Leading and trailing whitespace ignored.
+	// collect generic arg, terminated with comma or newline. Leading and trailing whitespace ignored.
+	PARS_ARG,
 	PARS_ARG_STR_APOS, // collect arg - string with single quotes
 	PARS_ARG_STR_QUOT, // collect arg - string with double quotes
 	PARS_ARG_BLOB_PREAMBLE,
+	// command with no args terminated by whitespace, discard whitespace until newline and then run callback.
+	// error on non-whitespace
+	PARS_DISCARD_WHITESPACE_ENDL,
 	PARS_DISCARD_LINE, // used after detecting error
 } parser_state_t;
 
@@ -19,42 +23,42 @@ typedef enum {
 /** parser internal state struct */
 static struct {
 	char err_queue[ERR_QUEUE_LEN][MAX_ERROR_LEN];
-	uint8_t err_queue_ptr;
+	uint8_t err_queue_i;
 
 	parser_state_t state; // current parser internal state
 
 	// string buffer, chars collected here until recognized
 	char charbuf[256];
-	uint16_t charbuf_ptr;
+	uint16_t charbuf_i;
 
 	// recognized complete command level strings (FUNCtion) - exact copy from command struct
 	char cur_levels[MAX_LEVEL_COUNT][MAX_CMD_LEN];
-	uint8_t cur_level_ptr; // next free level slot index
+	uint8_t cur_level_i; // next free level slot index
 
 	bool cmdbuf_kept; // set to 1 after semicolon - cur_levels is kept (removed last part)
 
-	SCPI_command_t *detected_cmd; // command is put here after recognition, used as reference for args
+	const SCPI_command_t * matched_cmd; // command is put here after recognition, used as reference for args
 
 	SCPI_argval_t args[MAX_PARAM_COUNT];
-	uint8_t arg_ptr; // next free argument slot index
+	uint8_t arg_i; // next free argument slot index
 } pstate = {
 	// defaults
-	.err_queue_ptr = 0,
+	.err_queue_i = 0,
 	.state = PARS_COMMAND,
-	.charbuf_ptr = 0,
-	.cur_level_ptr = 0,
+	.charbuf_i = 0,
+	.cur_level_i = 0,
 	.cmdbuf_kept = false,
-	.detected_cmd = NULL,
-	.arg_ptr = 0
+	.matched_cmd = NULL,
+	.arg_i = 0
 };
 
 
-
 static void pars_cmd_colon(void); // colon starting a command sub-segment
 static void pars_cmd_space(void); // space ending a command
 static void pars_cmd_newline(void); // LF
 static void pars_cmd_semicolon(void); // semicolon right after a command
-static void pars_match_level(void); // match charbuf content to a level, advance level ptr (or fail)
+static bool pars_match_cmd(bool partial);
+
 
 // char matching
 #define INRANGE(c, a, b) ((c) >= (a) && (c) <= (b))
@@ -64,39 +68,44 @@ static void pars_match_level(void); // match charbuf content to a level, advance
 #define IS_UCASE_CHAR(c) INRANGE((c), 'A', 'Z')
 #define IS_NUMBER_CHAR(c) INRANGE((c), '0', '9')
 
-#define IS_IDENT_CHAR(c) (IS_LCASE_CHAR((c)) || IS_UCASE_CHAR((c)) || IS_NUMBER_CHAR((c)) || (c) == '_')
+#define IS_IDENT_CHAR(c) (IS_LCASE_CHAR((c)) || IS_UCASE_CHAR((c)) || IS_NUMBER_CHAR((c)) || (c) == '_' || (c) == '*' || (c) == '?')
 #define IS_INT_CHAR(c) IS_NUMBER_CHAR((c))
 #define IS_FLOAT_CHAR(c) (IS_NUMBER_CHAR((c)) || (c) == '.' || (c) == 'e' || (c) == 'E' || (e) == '+' || (e) == '-')
 
+#define CHAR_TO_LOWER(ucase) ((ucase) + 32)
+#define CHAR_TO_UPPER(lcase) ((lcase) - 32)
+
+
 
 static void pars_reset_cmd(void)
 {
 	pstate.state = PARS_COMMAND;
-	pstate.charbuf_ptr = 0;
-	pstate.cur_level_ptr = 0;
+	pstate.charbuf_i = 0;
+	pstate.cur_level_i = 0;
 	pstate.cmdbuf_kept = false;
-	pstate.detected_cmd = NULL;
-	pstate.arg_ptr = 0;
+	pstate.matched_cmd = NULL;
+	pstate.arg_i = 0;
 }
 
+
 static void pars_reset_cmd_keeplevel(void)
 {
 	pstate.state = PARS_COMMAND;
-	pstate.charbuf_ptr = 0;
+	pstate.charbuf_i = 0;
 	// rewind to last colon
 
-	if (pstate.cur_level_ptr > 0) {
-		pstate.cur_level_ptr--; // keep prev levels
+	if (pstate.cur_level_i > 0) {
+		pstate.cur_level_i--; // keep prev levels
 	}
 
 	pstate.cmdbuf_kept = true;
 
-	pstate.detected_cmd = NULL;
-	pstate.arg_ptr = 0;
+	pstate.matched_cmd = NULL;
+	pstate.arg_i = 0;
 }
 
 
-void scpi_receive_byte(const uint8_t b)
+void scpi_handle_byte(const uint8_t b)
 {
 	// TODO handle blob here
 	const char c = (char) b;
@@ -105,7 +114,7 @@ void scpi_receive_byte(const uint8_t b)
 		case PARS_COMMAND:
 			// Collecting command
 
-			if (pstate.charbuf_ptr == 0 && pstate.cur_level_ptr == 0) {
+			if (pstate.charbuf_i == 0 && pstate.cur_level_i == 0) {
 				if (IS_WHITESPACE(c)) {
 					// leading whitespace is ignored
 					break;
@@ -116,8 +125,8 @@ void scpi_receive_byte(const uint8_t b)
 			if (IS_IDENT_CHAR(c)) {
 				// valid command char
 
-				if (pstate.charbuf_ptr < MAX_CMD_LEN) {
-					pstate.charbuf[pstate.charbuf_ptr++] = c;
+				if (pstate.charbuf_i < MAX_CMD_LEN) {
+					pstate.charbuf[pstate.charbuf_i++] = c;
 				} else {
 					printf("ERROR command part too long.\n");//TODO error
 					pstate.state = PARS_DISCARD_LINE;
@@ -127,7 +136,7 @@ void scpi_receive_byte(const uint8_t b)
 				// invalid or delimiter
 
 				if (IS_WHITESPACE(c)) {
-//					pars_cmd_space(); // whitespace in command - end of command?
+					pars_cmd_space(); // whitespace in command - end of command, start of args (?)
 					break;
 				}
 
@@ -137,7 +146,7 @@ void scpi_receive_byte(const uint8_t b)
 						break;
 
 					case '\n': // line terminator
-//						pars_cmd_newline();
+						pars_cmd_newline();
 						break;
 
 					case ';': // ends a command, does not reset cmd path.
@@ -159,16 +168,17 @@ void scpi_receive_byte(const uint8_t b)
 			break;
 
 			// TODO
+
 	}
 }
 
 
 static void pars_cmd_colon(void)
 {
-	if (pstate.charbuf_ptr == 0) {
+	if (pstate.charbuf_i == 0) {
 		// No command text before colon
 
-		if (pstate.cur_level_ptr == 0 || pstate.cmdbuf_kept) {
+		if (pstate.cur_level_i == 0 || pstate.cmdbuf_kept) {
 			// top level command starts with colon (or after semicolon - reset level)
 			pars_reset_cmd();
 		} else {
@@ -178,13 +188,40 @@ static void pars_cmd_colon(void)
 		}
 
 	} else {
-		// internal colon
-		pars_match_level();
+		// internal colon - partial match
+		if (pars_match_cmd(true)) {
+			printf("OK partial cmd, last segment = %s\n", pstate.cur_levels[pstate.cur_level_i - 1]);
+		} else {
+			printf("ERROR no such command (colon).\n");//TODO error
+			pstate.state = PARS_DISCARD_LINE;
+		}
+	}
+}
+
+
+static void pars_cmd_newline(void)
+{
+	if (pstate.cur_level_i == 0 && pstate.charbuf_i == 0) {
+		// nothing before newline
+		pars_reset_cmd();
+		return;
+	}
+
+	// complete match
+	if (pars_match_cmd(false)) {
+		if (pstate.matched_cmd->param_cnt == 0) {
+			// no param command - OK
+			pstate.matched_cmd->callback(pstate.args); // args are empty
+		} else {
+			printf("ERROR command missing arguments.\n");//TODO error
+			pars_reset_cmd();
+		}
+	} else {
+		printf("ERROR no such command (newline) %s.\n", pstate.charbuf);//TODO error
+		pstate.state = PARS_DISCARD_LINE;
 	}
 }
 
-#define CHAR_TO_LOWER(ucase) ((ucase) + 32)
-#define CHAR_TO_UPPER(lcase) ((lcase) - 32)
 
 
 /** Check if chars equal, ignore case */
@@ -248,12 +285,66 @@ static bool level_str_matches(const char *test, const char *pattern)
 }
 
 
+// proto
+static bool try_match_cmd(const SCPI_command_t *cmd, bool partial);
 
-static void pars_match_level(void)
+
+static bool pars_match_cmd(bool partial)
 {
 	// terminate segment
-	pstate.charbuf[pstate.charbuf_ptr] = '\0';
+	pstate.charbuf[pstate.charbuf_i] = '\0';
+	pstate.charbuf_i = 0; // rewind
+
+	char *dest = pstate.cur_levels[pstate.cur_level_i++];
+	strcpy(dest, pstate.charbuf); // copy to level table
+
+	for (uint16_t i = 0; i < scpi_cmd_lang_len; i++) {
+
+		const SCPI_command_t *cmd = &scpi_cmd_lang[i];
+
+		if (cmd->level_cnt > MAX_LEVEL_COUNT) {
+			// FAIL, too deep. Bad config
+			continue;
+		}
 
-	//TODO
+		if (try_match_cmd(cmd, partial)) {
+			if (partial) {
+				// match found, OK
+				return true;
+			} else {
+				// exact match found
+				pstate.matched_cmd = cmd;
+				return true;
+			}
+		}
+	}
+
+	return false;
 }
 
+
+/** Try to match current state to a given command */
+static bool try_match_cmd(const SCPI_command_t *cmd, bool partial)
+{
+	if (pstate.cur_level_i > cmd->level_cnt) return false; // command too short
+	if (pstate.cur_level_i == 0) return false; // nothing to match
+
+	if (partial) {
+		if (pstate.cur_level_i == cmd->level_cnt) {
+			return false; // would be exact match
+		}
+	} else {
+		if (pstate.cur_level_i != cmd->level_cnt) {
+			return false; // can be only partial match
+		}
+	}
+
+	// check for match up to current index
+	for (uint8_t j = 0; j < pstate.cur_level_i; j++) {
+		if (!level_str_matches(pstate.cur_levels[j], cmd->levels[j])) {
+			return false;
+		}
+	}
+
+	return true;
+}
diff --git a/scpi_parser.h b/scpi_parser.h
index dce2d7a..76dfa49 100644
--- a/scpi_parser.h
+++ b/scpi_parser.h
@@ -49,4 +49,4 @@ extern const uint16_t scpi_cmd_lang_len; // number of commands
 extern const SCPI_command_t scpi_cmd_lang[];
 
 // --------------- functions --------------------
-
+void scpi_handle_byte(const uint8_t b);