From 8540be950a63bc7dddec120893e939ef9afef178 Mon Sep 17 00:00:00 2001
From: Michael Moon <triffid.hunter@gmail.com>
Date: Sun, 20 Feb 2011 17:13:09 +1100
Subject: [PATCH] use CRC16 to verify heater PID settings in eeprom

---
 Makefile |  2 +-
 crc.c    | 24 ++++++++++++++++++++++++
 crc.h    |  8 ++++++++
 heater.c | 13 +++++++++----
 4 files changed, 42 insertions(+), 5 deletions(-)
 create mode 100644 crc.c
 create mode 100644 crc.h

diff --git a/Makefile b/Makefile
index 9bd9a90..9bc1430 100644
--- a/Makefile
+++ b/Makefile
@@ -96,7 +96,7 @@ PROGBAUD = 57600
 
 PROGRAM = mendel
 
-SOURCES = $(PROGRAM).c serial.c dda.c gcode_parse.c gcode_process.c timer.c temp.c sermsg.c dda_queue.c watchdog.c debug.c sersendf.c heater.c analog.c delay.c intercom.c pinio.c clock.c home.c
+SOURCES = $(PROGRAM).c serial.c dda.c gcode_parse.c gcode_process.c timer.c temp.c sermsg.c dda_queue.c watchdog.c debug.c sersendf.c heater.c analog.c delay.c intercom.c pinio.c clock.c home.c crc.c
 
 ARCH = avr-
 CC = $(ARCH)gcc
diff --git a/crc.c b/crc.c
new file mode 100644
index 0000000..2a8a10c
--- /dev/null
+++ b/crc.c
@@ -0,0 +1,24 @@
+#include	"crc.h"
+
+#include	<util/crc16.h>
+
+// 	uint16_t _crc16_update(uint16_t crc, uint8_t a) {
+// 		int i;
+// 		crc ^= a;
+// 		for (i = 0; i < 8; ++i)
+// 		{
+// 			if (crc & 1)
+// 				crc = (crc >> 1) ^ 0xA001;
+// 			else
+// 				crc = (crc >> 1);
+// 		}
+// 		return crc;
+// 	}
+
+uint16_t	crc_block(void *data, uint16_t len) {
+	uint16_t	crc = 0;
+	for (; len; data++, len--) {
+		crc = _crc16_update(crc, *((uint8_t *) data));
+	}
+	return crc;
+}
diff --git a/crc.h b/crc.h
new file mode 100644
index 0000000..7cd9852
--- /dev/null
+++ b/crc.h
@@ -0,0 +1,8 @@
+#ifndef	_CRC_H
+#define	_CRC_H
+
+#include	<stdint.h>
+
+uint16_t	crc_block(void *data, uint16_t len);
+
+#endif	/* _CRC_H */
diff --git a/heater.c b/heater.c
index 35288ca..3e50f8f 100644
--- a/heater.c
+++ b/heater.c
@@ -6,10 +6,12 @@
 
 #include	"arduino.h"
 #include	"debug.h"
-#ifndef	EXTRUDER
-#include	"sersendf.h"
-#endif
 #include	"temp.h"
+#include	"crc.h"
+
+#ifndef	EXTRUDER
+	#include	"sersendf.h"
+#endif
 
 typedef struct {
 	volatile uint8_t *heater_port;
@@ -59,6 +61,7 @@ typedef struct {
 	int32_t		EE_i_factor;
 	int32_t		EE_d_factor;
 	int16_t		EE_i_limit;
+	uint16_t	crc;
 } EE_factor;
 
 EE_factor EEMEM EE_factors[NUM_HEATERS];
@@ -101,7 +104,8 @@ void heater_init() {
 			heaters_pid[i].d_factor = eeprom_read_dword((uint32_t *) &EE_factors[i].EE_d_factor);
 			heaters_pid[i].i_limit = eeprom_read_word((uint16_t *) &EE_factors[i].EE_i_limit);
 
-			if ((heaters_pid[i].p_factor == 0) && (heaters_pid[i].i_factor == 0) && (heaters_pid[i].d_factor == 0) && (heaters_pid[i].i_limit == 0)) {
+// 			if ((heaters_pid[i].p_factor == 0) && (heaters_pid[i].i_factor == 0) && (heaters_pid[i].d_factor == 0) && (heaters_pid[i].i_limit == 0)) {
+			if (crc_block(&heaters_pid[i].p_factor, 14) != eeprom_read_word((uint16_t *) &EE_factors[i].crc)) {
 				heaters_pid[i].p_factor = DEFAULT_P;
 				heaters_pid[i].i_factor = DEFAULT_I;
 				heaters_pid[i].d_factor = DEFAULT_D;
@@ -119,6 +123,7 @@ void heater_save_settings() {
 			eeprom_write_dword((uint32_t *) &EE_factors[i].EE_i_factor, heaters_pid[i].i_factor);
 			eeprom_write_dword((uint32_t *) &EE_factors[i].EE_d_factor, heaters_pid[i].d_factor);
 			eeprom_write_word((uint16_t *) &EE_factors[i].EE_i_limit, heaters_pid[i].i_limit);
+			eeprom_write_word((uint16_t *) &EE_factors[i].crc, crc_block(&heaters_pid[i].p_factor, 14));
 		}
 	#endif /* BANG_BANG */
 }