uart: fix uart_break_p() polarity

.gitignore

@@ -15,4 +15,4 @@ gerber/*.pdf
 *.map
 *.o
 *.s
-
+*.EI

src/Makefile

@@ -8,14 +8,14 @@ all: $(PROJ).hex
 
 SN_bate = 1
 MCU_bate = attiny424
-C_FILES_bate = uart.c rtc.c calib.c
+C_FILES_bate = uart.c rtc.c calib.c mul.c
 
 BATE_PERIOD=76
 bate_CFLAGS = -DPERIOD=$(BATE_PERIOD)
 
 MCU = $(MCU_$(PROJ))
 
-CC=avr-gcc -v -Wall -Wno-parentheses -MMD -std=c99 -O3 \
+CC=avr-gcc -v -Wall -Wno-parentheses -MMD -std=c99 -O2 \
   -mmcu=$(MCU) \
   -funsigned-char \
   -funsigned-bitfields \
@@ -113,6 +113,11 @@ fuse: $(PROJ).fuse$F
 	echo "$*: fuse$F = $(fuse$F_$*)"
 	[ -n "$(fuse$F_$*)" ] && $(AD) -B 5 -U fuse$F:w:$(fuse$F_$*):m
 
+BATE_CONFIG=0xba 0x01 0x00 0x8a 0x08 0x00 0xff 0xff 0x00 0x00
+bate.config:
+	$(AD) -U userrow:v:"$(BATE_CONFIG)":m \
+     ||	$(AD) -U userrow:w:"$(BATE_CONFIG)":m
+
 clean:
 	rm -f *.hex *.o *.s *.map *.elf *.d
 

src/bate.c

@@ -5,6 +5,8 @@
 // !!! int = int8_t
 
 #include <stdint.h>
+#include <string.h>
+
 #include <avr/io.h>
 #include <avr/interrupt.h>
 #include <avr/sleep.h>
@@ -87,7 +89,7 @@ void rfen(uint8_t on)
 static inline
 void init_mclk(uint8_t p)
 {
-	if (p < 120 || p > 200)
+	if (p < 50 || p > 100)
 		p = PERIOD;
 	PORTB.DIRSET = Bit(0);
 	MCLK.INTCTRL = TCA_SINGLE_CMP0_bm;
@@ -293,18 +295,25 @@ void read_bate()
 
 ////////////////////////////////////////////////////////////////////////////////
 //
-//  Configutarion in USERROW
+//  Configuration in USERROW
 
 struct config {
+	uint8_t magic;
+	uint8_t version;
 	uint8_t power;
 	uint8_t send;
 	uint8_t triggers;
 	uint8_t mclk_period;
+	uint8_t mclk_delay;
+	uint8_t pit_period;
 	uint16_t baud_div;
-	uint16_t mclk_delay;
 };
 
-static const struct config *config = (struct config *) & USERROW;
+enum magic_flags {
+	USE_USERROW       = 0xBA,
+	USE_VERSION       = 0x01,
+};
+
 
 enum power_flags {
 	POWER_DOWN        = 0x01,
@@ -316,6 +325,7 @@ enum send_flags {
 	SEND_CLOCK        = 0x02,
 	SEND_HEX          = 0x04,
 	SEND_CALIB        = 0x08,
+	SEND_DEBUG        = 0x80,
 };
 enum trigger_flags {
 	TRIGGER_ONCE  = 0x01,
@@ -325,6 +335,15 @@ enum trigger_flags {
 	TRIGGER_BREAK = 0x10,
 };
 
+static struct config config_ram = {
+	.send       = SEND_BOOT_MESSAGE | SEND_CLOCK | SEND_DEBUG,
+	.triggers   = TRIGGER_CONT,
+	.mclk_delay = 0xff,
+	.pit_period = RTC_CLKSEL_INT1K_gc,
+};
+static struct config *config = & config_ram;
+static const struct config *userrow = (struct config *) & USERROW;
+
 ////////////////////////////////////////////////////////////////////////////////
 //
 //  main()
@@ -334,11 +353,16 @@ int main()
 	CCP = CCP_IOREG_gc;
 	CLKCTRL.MCLKCTRLB = CLKCTRL_PDIV_2X_gc | 1;
 	BATE_PORT.DIRSET = Bit(SCK_PORT) | Bit(DIN_PORT);
+
+	if (userrow->magic == USE_USERROW
+	    && userrow->version == USE_VERSION)
+		memcpy(config, &USERROW, sizeof(USERROW));
+
 	init_mclk(config->mclk_period);
 	init_led();
 	init_rfen();
 	init_uart(config->baud_div);
-	init_rtc();
+	init_rtc(config->pit_period);
 
 	rfen(1);
 
@@ -346,26 +370,61 @@ int main()
 	sleep_enable();
 	sei();
 
+	send_str("Hallo\n");
+
 	if (config->send & SEND_BOOT_MESSAGE) {
 		send_str("V Turbo Weather V0.01\n");
 		send_hex('S', (uint8_t *)&SIGROW, sizeof(SIGROW_t));
 		send_hex('F', (uint8_t *)&FUSE, sizeof(FUSE_t));
 		send_hex('U', (uint8_t *)&USERROW, sizeof(USERROW_t));
+		send_hex('C', (uint8_t *)config, sizeof(struct config));
 	}
 
 	uint8_t trigger = TRIGGER_CONT | TRIGGER_ONCE;
 	uint8_t mclk_delay = config->mclk_delay;
 
+//#define BATE_DEBUG
+#ifdef BATE_DEBUG
+	uint16_t nn = 0;
+	uint8_t depth = 0;
+#  define DEPTH(w, d) do { if (n>=w && d!=depth) {nn=n; n=0;} depth=d; } while(0)
+#else
+#  define DEPTH(w, d)
+#endif
+
+	uint16_t n = 0;
+	uint16_t itest = 0;
+	static const union bate testdata[4] = {
+		{ .W = { 0xabaf, 0x3c99, 0xa31a, 0xb589}, .D = { 0x470c, 0x773f }, }, //  21.2 °C, 1021.7 mbar
+		{ .W = { 0xabaf, 0x3c99, 0xa31a, 0xb589}, .D = { 0x1a51, 0x6fed }, }, //   7.5 °C, 5.4 mbar
+		{ .W = { 0xaa3d, 0x35d9, 0xcbe5, 0xb736}, .D = { 0x4bb7, 0x7487 }, }, //  17.7 °C, 1023.0 mbar
+		{ .W = { 0xaa3d, 0x35d9, 0xcbe5, 0xb736}, .D = { 0x1e25, 0x650a }, }, // -11.3 °C, 2.4 mbar
+	};
+
 	while (1) {
+
+#ifdef BATE_DEBUG
+		if (!n && config->send & SEND_DEBUG) {
+			send_str("D ");
+			send_hex_byte(depth);
+			send_hex_word(nn);
+			send_hex_word(clock);
+			send_char_sleep('\n');
+		}
+		led(n & 1);
+#endif
+
+		n++;
 		sleep_cpu();
+
 		if (uart_busy()) {
 			uart_tick();
+			DEPTH(4096, 1);
 			continue;
 		}
 		wdt_reset();
 
 		rfen(0);
-		led(0);
 
 		if (uart_tick())
 			trigger |= TRIGGER_UART;
@@ -375,6 +434,7 @@ int main()
 			trigger |= TRIGGER_CLOCK;
 
 		if (!(trigger & config->triggers)) {
+			DEPTH(0, 2);
 			if (config->power & POWER_DOWN) {
 				mclk(0);
 				if (config->power & POWER_DOWN_CLI)
@@ -382,12 +442,16 @@ int main()
 				set_sleep_mode(SLEEP_MODE_PWR_DOWN);
 				sleep_enable();
 				sleep_cpu();
+				set_sleep_mode(SLEEP_MODE_IDLE);
+				DEPTH(0, 3);
 			}
 			continue;
 		}
 
-		if (!tick)
+		if (!tick) {
+			DEPTH(256, 4);
 			continue;
+		}
 		tick = 0;
 
 		if (!mclk_status()) {
@@ -396,11 +460,11 @@ int main()
 		}
 		if (mclk_delay) {
 			mclk_delay--;
+			DEPTH(0, 5);
 			continue;
 		}
+		DEPTH(0, 6);
 
-		trigger = TRIGGER_CONT;
-		led(1);
 		rfen(1);
 		cli();
 		uint32_t time = clock;
@@ -413,12 +477,15 @@ int main()
 		if (config->send & SEND_CLOCK) {
 			send_str("T 0x");
 			send_hex_long(time);
+			send_str(" 0x");
+			send_hex_byte(trigger);
 			send_char_sleep('\n');
 		}
 		if (config->send & SEND_HEX)
 			send_hex('B', bate.b, sizeof(bate));
 		if (config->send & SEND_CALIB) {
-			bate_calib(&bate, &pressure);
+//			bate_calib(&bate, &pressure);
+			bate_calib(testdata+(itest++&3), &pressure);
 			send_str("P ");
 			send_decimal(pressure.p, 1);
 			send_str(" mbar, ");
@@ -427,5 +494,6 @@ int main()
 		}
 		uart_tick();
 		clock_tick = 0;
+		trigger = TRIGGER_CONT;
 	}
 }

src/calib.c

@@ -6,26 +6,38 @@
 // https://media.digikey.com/pdf/Data%20Sheets/Measurement%20Specialties%20PDFs/MS5534-CM.pdf
 
 #include "calib.h"
+#include "mul.h"
 
 void bate_calib(union bate *bate, struct pressure *pt)
 {
 	uint16_t C1 = bate->W1 >> 1;
 	uint16_t C5 = (bate->W1 & 1) << 13 | (bate->W2 & 0xffc0) >> 4;
 	uint8_t  C6 = bate->W2 & 63;
-	uint16_t C4 = bate->W3 >> 6;
+	uint16_t C4 = bate->W3 >> 2  &  0x3ff0;
 	uint16_t C3 = bate->W4 >> 6;
 	uint16_t C2 = (bate->W3&63) << 8 | (bate->W4&63) << 2;
 
 	uint16_t D1 = bate->D1;
 	uint16_t D2 = bate->D2;
 
-	uint16_t UT1 = C5 + 20224;
-	int32_t  dT   = D2-UT1;
-	uint16_t TEMP = ((uint32_t)(dT*(C6 + 50) >> 2) >> 8) + 200;
-	uint16_t OFF  = C2 + ((uint32_t)((C4 - 512LL)*dT >> 4) >> 8);
-	uint16_t SENS = C1 + ((uint32_t)(C3*dT >> 2) >> 8) + 24576;
-	uint16_t X = ((uint32_t)(SENS*(D1-7168LL) << 2) >> 16) - OFF;
-	uint16_t P = ((uint32_t)(X*80LL) >> 8) + 2500;
-	pt->T = TEMP - 2732;
+	uint16_t UT1  = C5 + 20224;
+	int32_t  dT   = D2 - UT1;
+
+	uint16_t TEMPSENS = C6 + 50;
+	uint16_t TEMP = mul16su(dT, TEMPSENS) + 200;
+
+	int16_t  TCO = C4 - (512<<4);
+	uint16_t OFFT1 = C2;
+	uint16_t OFF  = OFFT1 + mul16ss(dT, TCO);
+
+	uint16_t SENST1 = C1 + 24576;
+	uint16_t TCS = C3 << 4;
+	uint16_t SENS = SENST1 + mul16su(dT, TCS);
+
+	uint16_t X = mul16uu((D1-7168)<<2, SENS) - OFF;
+
+	uint16_t P = mul16su(X, 20480) + 2500;
+
+	pt->T = TEMP + 2732;
 	pt->p = P;
 }

src/calib.py

@@ -0,0 +1,76 @@
+#!/usr/bin/python3
+# encoding: UTF-8
+
+import sys
+
+def calibrate(Word, D):
+
+    print(f"""INPUT Words
+W1 = 0x{Word[1]:04x}
+W2 = 0x{Word[2]:04x}
+W3 = 0x{Word[3]:04x}
+W4 = 0x{Word[4]:04x}
+D1 = 0x{D[1]:04x}
+D2 = 0x{D[2]:04x}
+""", file=sys.stderr)
+
+    C=[0]*7
+    C[1] = Word[1] >> 1
+    C[2] = ((Word[3] & 0x3f)<<6) | (Word[4] & 0x3f) 
+    C[3] = Word[4]>>6
+    C[4] = Word[3]>>6
+    C[5] = ((Word[1] & 1)<<10) | (Word[2]>>6)
+    C[6] = Word[2] & 0x3f
+
+    print(f"""CAL Words
+C1 = {C[1]}
+C2 = {C[2]}
+C3 = {C[3]}
+C4 = {C[4]}
+C5 = {C[5]}
+C6 = {C[6]}
+""", file=sys.stderr)
+    
+    UT1 = 8*C[5]+20224
+    dT = D[2] - UT1
+    TEMPSENSE = C[6]+50
+    TEMP = 200 + dT*TEMPSENSE//1024
+    
+    print(f"""Temperature
+D2        = {D[2]}
+UT1       = {UT1}
+dT        = {dT}
+TSENSENSE = {TEMPSENSE}
+TEMP      = {TEMP*0.1:.1f} °C
+""", file=sys.stderr)
+
+    TCO = C[4]-512
+    OFFT1 = C[2]*4 
+    OFF = OFFT1 + (TCO*dT) // 4096
+
+    SENST1 = C[1] + 24576;
+    TCS = C[3]
+    SENS = SENST1 + (TCS*dT) // 1024
+    X = (SENS * (D[1]-7168)) // 16384 - OFF
+    P = X*10//32 + 2500
+    
+    print(f"""Pressure
+D1    = {D[1]} {D[1]-7168}10
+TCO   = {TCO}
+OFFT1 = {OFFT1} 
+OFF   = {OFF}
+TCS   = {TCS}
+SENST1= {SENST1}
+SENS  = {SENS}  {SENS/2**14}
+X     = {X}
+P     = {P*0.1:.1f} mbar
+""", file=sys.stderr)
+
+    return (TEMP,P)
+
+for l in sys.stdin:
+    if l[0]!='P':
+        continue
+    Word=[None]
+    Word.extend([int(ll,0) for ll in l.split()[1:]])
+    calibrate(Word, Word[4:])

src/mul.c

@@ -0,0 +1,119 @@
+//
+// mul.c
+//
+
+#include <stdint.h>
+
+int16_t mul16su(int16_t s, int16_t u)
+{
+	__asm__(
+		"movw  r18, %[s]"	"\n\t"
+		"mul   r18, %A[u]"	"\n\t"
+		"mov   r20, r1"		"\n\t"
+		"mulsu r19, %B[u]"	"\n\t"
+		"movw  %[s], r0"	"\n\t"
+		"mul   r18, %B[u]"	"\n\t"
+		"clr   r18"		"\n\t"
+		"add   r20, r0"		"\n\t"
+		"adc   %A[s], r1"	"\n\t"
+		"adc   %B[s], r18"	"\n\t"
+		"mulsu r19, %A[u]"	"\n\t"
+		"sbc   %B[s], r18"	"\n\t"
+		"add   r20, r0"		"\n\t"
+		"adc   %A[s], r1"	"\n\t"
+		"adc   %B[s], r18"	"\n\t"
+		"clr   r1"		"\n\t"
+		: [s] "+r" (s)
+		: [u] "a" (u)
+		: "r0", "r1", "r18", "r19", "r20"
+		);
+	return s;
+}
+
+int16_t mul16ss(int16_t a, int16_t b)
+{
+        // ((int32_t)a*b) >> 16
+	__asm__(
+		"movw  r18, %[a]"	"\n\t"
+		"mul   r18, %A[b]"	"\n\t"
+		"mov   r20, r1"		"\n\t"
+		"muls  r19, %B[b]"	"\n\t"
+		"movw  %[a], r0"	"\n\t"
+		"mulsu %B[b], r18"	"\n\t"
+		"clr   r18"		"\n\t"
+		"sbc   %B[a], r18"	"\n\t"
+		"add   r20, r0"		"\n\t"
+		"adc   %A[a], r1"	"\n\t"
+		"adc   %B[a], r18"	"\n\t"
+		"mulsu r19, %A[b]"	"\n\t"
+		"sbc   %B[a], r18"	"\n\t"
+		"add   r20, r0"		"\n\t"
+		"adc   %A[a], r1"	"\n\t"
+		"adc   %B[a], r18"	"\n\t"
+		"clr   r1"		"\n\t"
+		: [a] "+r" (a)
+		: [b] "a" (b)
+		: "r0", "r1", "r18", "r19", "r20"
+		);
+	return a;
+}
+
+int16_t mul16uu(int16_t a, int16_t b)
+{
+        // ((uint32_t)a*(uint32_t)b) >> 16
+	__asm__(
+		"movw  r18, %[a]"	"\n\t"
+		"mul   r18, %A[b]"	"\n\t"
+		"mov   r20, r1"		"\n\t"
+		"mul   r19, %B[b]"	"\n\t"
+		"movw  %[a], r0"	"\n\t"
+		"mul  %B[b], r18"	"\n\t"
+		"clr   r18"		"\n\t"
+		"add   r20, r0"		"\n\t"
+		"adc   %A[a], r1"	"\n\t"
+		"adc   %B[a], r18"	"\n\t"
+		"mul   r19, %A[b]"	"\n\t"
+		"add   r20, r0"		"\n\t"
+		"adc   %A[a], r1"	"\n\t"
+		"adc   %B[a], r18"	"\n\t"
+		"clr   r1"		"\n\t"
+		: [a] "+r" (a)
+		: [b] "a" (b)
+		: "r0", "r1", "r18", "r19", "r20"
+		);
+	return a;
+}
+
+uint16_t divmod10(uint16_t u, uint8_t *mod)
+{
+	uint16_t r;
+	uint8_t d; 
+	__asm__(
+		"ldi   r18, lo8(6554)"	"\n\t"
+		"ldi   r19, hi8(6554)"	"\n\t"
+		"mul   r18, %A[u]"	"\n\t"
+		"mov   r20, r1"		"\n\t"
+		"mul   r19, %B[u]"	"\n\t"
+		"movw  %[r], r0"	"\n\t"
+		"mul   r19, %A[u]"	"\n\t"
+		"clr   r19"		"\n\t"
+		"add   r20, r0"		"\n\t"
+		"adc   %A[r], r1"	"\n\t"
+		"adc   %B[r], r19"	"\n\t"
+		"mul   r18, %B[u]"	"\n\t"
+		"add   r20, r0"		"\n\t"
+		"adc   %A[r], r1"	"\n\t"
+		"adc   %B[r], r19"	"\n\t"
+		"ldi   r19, lo8(10)"	"\n\t"
+		"mul   r19, r20"	"\n\t"
+		"mov   %[d], r1"	"\n\t"
+		"clr   r1"		"\n\t"
+		: [r] "=&r" (r),
+		  [d] "=r" (d)
+		: [u] "d" (u)
+		: "r0", "r1", "r18", "r19", "r20"
+		);
+	*mod = d;
+	return r;
+}
+

src/mul.h

@@ -0,0 +1,8 @@
+//
+// mul.h
+//
+
+int16_t mul16su(int16_t s, int16_t u);
+int16_t mul16ss(int16_t a, int16_t b);
+int16_t mul16uu(int16_t a, int16_t b);
+uint16_t divmod10(uint16_t u, uint8_t *mod);

src/mul.py

@@ -0,0 +1,73 @@
+
+def mul(a,b):
+    return  (a & 0xff) * (b & 0xff)
+
+def mulsu(a,b):
+    a &= 0xff
+    if a & 0x80:
+        a |= 0xff00
+    return (a * (b&0xff)) & 0xffff
+
+def mul16su(a, b):
+    a &= 0xffff
+    b &= 0xffff
+    ah = a>>8
+    al = a & 0xff
+    bh = b>>8
+    bl = b & 0xff
+    r = mulsu(ah, bh) << 16
+    r |= mul(al, bl)
+    rr = mulsu(ah, bl)
+    if rr & 0x8000:
+        r -= 0x1000000
+    #c = r & 0x1000000
+    r += rr << 8
+    #if c != (r & 0x1000000):
+    #    r += 0x1000000
+    r += mul(al, bh) << 8
+    return r & 0xffffffff
+
+def test():
+    errors = 0
+    for s in range(2):
+        for l in range(4):
+            for a in range(64, 128):
+                for b in range(64, 128):
+                    for c in range(9):
+                        for d in range(10):
+                            e = a << (8-c)
+                            if l & 1:
+                                e ^= 0xff >> c
+                            if (s):
+                                e = -e
+                            f = b << (9-d)
+                            if l & 2:
+                                f ^= 0x1ff >> c
+                            r = mul16su(e, f)
+                            rr = (e*f) & 0xffffffff
+                            if r != rr:
+                                print("ERROR", e,f,hex(r),hex(rr))
+                                errors += 1
+                            else:
+                                print(e,f,r)
+    print(errors, "Errors")
+    return errors
+
+def full():
+    errors = 0
+    for u in range(0x10000):
+        print(u)
+        for s in range(0x8000):
+            r = mul16su(s, u)
+            rr = (s*u) & 0xffffffff
+            if r != rr:
+                print("ERROR", s, u, hex(r), hex(rr))
+                errors += 1
+        for s in range(0x8000):
+            r = mul16su(-s, u)
+            rr = (-s*u) & 0xffffffff
+            if r != rr:
+                print("ERROR", -s, u, hex(r), hex(rr))
+                errors += 1
+    print(errors, "Errors")
+    return errors

src/rtc.c

@@ -15,13 +15,15 @@
 uint32_t clock;
 uint8_t clock_tick;
 
-void init_rtc()
+void init_rtc(uint8_t p)
 {
+	if (p>=16)
+		p = RTC_PERIOD_CYC1024_gc;
 	RTC.CLKSEL = RTC_CLKSEL_INT1K_gc;
 	RTC.PITINTCTRL = 1;
-	RTC.PITCTRLA = RTC_PERIOD_CYC1024_gc;
+	RTC.PITCTRLA = p;
 	while (RTC.PITSTATUS & 1) ;
-	RTC.PITCTRLA = RTC_PERIOD_CYC1024_gc | 1;
+	RTC.PITCTRLA = p | 1;
 }
 
 #if 1
@@ -31,6 +33,7 @@ ISR(RTC_PIT_vect, ISR_NAKED)
 		 "in r24, __SREG__"    "\n\t"
 		 "push r24"            "\n\t"
 		 "ldi r24,1"           "\n\t"
+		 "sts %[flag], r24"    "\n\t"
 		 "sts %[tick], r24"    "\n\t"
 		 "lds r24, %[clock]"   "\n\t"
 		 "subi r24, -1"        "\n\t"
@@ -50,12 +53,14 @@ ISR(RTC_PIT_vect, ISR_NAKED)
 		 "reti"                "\n"
 		 :[tick] "+m" (clock_tick),
 		  [clock] "+m" (clock)
+		 :[flag] "n" (&RTC.PITINTFLAGS)
 		);
 }
 #else
 ISR(RTC_PIT_vect)
 {
 	clock_tick = 1;
+	RTC.PITINTFLAGS = 1;
 	clock++;
 }
 #endif

src/rtc.h

@@ -6,4 +6,4 @@
 
 extern uint32_t clock;
 extern uint8_t clock_tick;
-void init_rtc();
+void init_rtc(uint8_t p);

src/uart.c

@@ -5,6 +5,7 @@
 // !!! int = int8_t
 
 #include "uart.h"
+#include "mul.h"
 
 #include <avr/interrupt.h>
 #include <avr/sleep.h>
@@ -54,6 +55,7 @@ uint8_t uart_tick()
 static uint8_t uart_tx[64];
 static uint8_t uart_tx_w;
 static uint8_t uart_tx_r;
+static const uint8_t uart_tx_m = sizeof(uart_tx) - 1;
 
 static inline void tx()
 {
@@ -65,8 +67,8 @@ static inline void tx()
 			uart_tx_r = r;
 			return;
 		}
-		USART0.TXDATAL = uart_tx[r];
-		r = (r+1) & (sizeof(uart_tx)-1);
+		USART0.TXDATAL = uart_tx[r & uart_tx_m];
+		r++;
 	}
 	uart_tx_r = r;
 	USART0.CTRLA &=~ USART_DREIE_bm;
@@ -77,37 +79,38 @@ ISR(USART0_DRE_vect)
 	tx();
 }
 
+__attribute__ ((noinline, noclone))
 uint8_t uart_busy()
 {
-	return (uart_tx_w - uart_tx_r) & (sizeof(uart_tx) - 1);
+	cli();
+	tx();
+	uint8_t r = uart_tx_w - uart_tx_r;
+	sei();
+	return r;
 }
 
 __attribute__ ((noinline, noclone))
 uint8_t send_char(uint8_t c)
 {
-	uint8_t ww = (uart_tx_w+1) & (sizeof(uart_tx)-1);
-	if (ww==uart_tx_r)
-		return 0;
-	uart_tx[uart_tx_w] = c;
+	uint8_t r = 0;
+	uint8_t ww = uart_tx_w + 1;
+	if ((ww & uart_tx_m) == (uart_tx_r & uart_tx_m))
+		goto full;
+	r = 1;
+	uart_tx[uart_tx_w & uart_tx_m] = c;
 	__asm__("" ::: "memory");
 	uart_tx_w = ww;
 	__asm__("" ::: "memory");
-	cli();
-	tx();
-	sei();
-	return 1;
-}
-
-void send_char_sleep(uint8_t c)
-{
-	while (!send_char(c))
-		sleep_cpu();
+full:
+	uart_busy();
+	return r;
 }
 
 uint8_t uart_rx[16];
 static uint8_t uart_rx_w;
 uint8_t uart_rx_n;
-uint8_t uart_rx_m;
+static const uint8_t uart_rx_m = sizeof(uart_rx) - 1;
+uint8_t uart_rx_mes;
 
 ISR(USART0_RXC_vect)
 {
@@ -115,12 +118,12 @@ ISR(USART0_RXC_vect)
 	uint8_t n = uart_rx_n;
 	while (USART0.STATUS & USART_RXCIF_bm) {
 		uint8_t c = USART0.RXDATAL;
-		uart_rx[w] = c;
+		uart_rx[w & uart_rx_m] = c;
 		n++;
-		if (w < sizeof(uart_rx)-1)
+		if (w < uart_rx_m)
 			w++;
 		if (c=='\n')
-			uart_rx_m = w;
+			uart_rx_mes = w;
 	}
 	uart_rx_w = w;
 	uart_rx_n = n;
@@ -131,19 +134,35 @@ void rx_dismiss(uint8_t n)
 {
 	cli();
 	uint8_t i = 0;
-	uart_rx_m = 0;
-	if (uart_rx_w != sizeof(uart_rx)-1)
+	uart_rx_mes = 0;
+	if (uart_rx_w != uart_rx_m)
 		while (n < uart_rx_w) {
 			uint8_t c = uart_rx[n++];
 			uart_rx[i++] = c;
 			if (c=='\n')
-				uart_rx_m = i;
+				uart_rx_mes = i;
 		}
 	uart_rx_w = i;
 	uart_rx_n = i;
 	sei();	
 }
 
+static __attribute__ ((noinline, noclone))
+void send_hex_nibble(uint8_t b)
+{
+	b += '0';
+	if (b>'9')
+		b += '@' - '9'; 
+	send_char_sleep(b);
+}
+
+__attribute__ ((noinline, noclone))
+void send_hex_byte(uint8_t b)
+{
+	send_hex_nibble(b >> 4);
+	send_hex_nibble(b & 0xf);
+}
+
 __attribute__ ((noinline, noclone))
 void send_hex_word(uint16_t b)
 {
@@ -171,20 +190,15 @@ void send_hex(uint8_t header, uint8_t *s, uint8_t n)
 __attribute__ ((noinline, noclone))
 void send_decimal(uint16_t b, uint8_t dec)
 {
-	uint8_t c[5];
+	char c[7];
+	c[6] = 0;
 	uint8_t n = 0;
-	while (b) {
-		uint16_t bb = b/10;
-		uint16_t bbb = bb * 10;
-		c[n++] = b - bbb + '0';
-		b = bb;
+	uint8_t d;
+	while ((b || n < dec) && n<6) {
+		b = divmod10(b, &d);
+		c[5-n++] = '0'+d;
+		if (n==dec)
+			c[5-n++] = '.';
 	}
-	if (n <= dec)
-		send_char('0');
-	while (n-->dec)
-		send_char(c[n]);
-	if (dec)
-		send_char('.');
-	while (n--)
-		send_char(c[n]);
+	send_str(c+6-n);
 }

src/uart.h

@@ -4,43 +4,41 @@
 
 #include <stdint.h>
 #include <avr/io.h>
+#include <avr/sleep.h>
 
 void init_uart(uint16_t div);
 uint8_t uart_tick();
 uint8_t uart_busy();
 uint8_t send_char(uint8_t c);
-void send_char_sleep(uint8_t c);
 extern uint8_t uart_rx[16];
 extern uint8_t uart_rx_n;
-extern uint8_t uart_rx_m;
+extern uint8_t uart_rx_mes;
 void rx_dismiss(uint8_t n);
 
 static inline
 uint8_t uart_break_p()
 {
-	return VPORTB.IN & 0x08;
-}
-
-static inline
-void send_hex_nibble(uint8_t b)
-{
-	send_char_sleep(b<10 ? b+'0' : b+'A'-'9'+1);
-}
-static inline
-void send_hex_byte(uint8_t b)
-{
-	send_hex_nibble(b >> 4);
-	send_hex_nibble(b & 0xf);
+	return !(VPORTB.IN & 0x08);
 }
 
+void send_hex_byte(uint8_t b);
 void send_hex_word(uint16_t b);
 void send_hex_long(uint32_t b);
 void send_hex(uint8_t header, uint8_t *s, uint8_t n);
 void send_decimal(uint16_t b,  uint8_t dec);
 
+
+static inline
+void send_char_sleep(uint8_t c)
+{
+	while (!send_char(c))
+		sleep_cpu();
+}
+
 static inline
 void send_str(char *s)
 {
 	while (*s)
 		send_char_sleep(*s++);
 }
+