From: Mikko Rasa <tdb@tdb.fi>
Date: Wed, 3 Jul 2013 16:13:56 +0000 (+0300)
Subject: Implement current and voltage monitoring
X-Git-Url: http://git.tdb.fi/?a=commitdiff_plain;h=817742862a867673e4cbdb85d274481f7482e1ae;p=model-railway-devices.git

Implement current and voltage monitoring
---

diff --git a/arducontrol/Makefile b/arducontrol/Makefile
index 1ffdd1d..22864ff 100644
--- a/arducontrol/Makefile
+++ b/arducontrol/Makefile
@@ -1,3 +1,3 @@
 include ../common/build.mk
 
-arducontrol.elf: motorola.o packet.o serial.o timer.o
+arducontrol.elf: adc.o motorola.o packet.o serial.o timer.o
diff --git a/arducontrol/arducontrol.c b/arducontrol/arducontrol.c
index 7b0c636..d09fc09 100644
--- a/arducontrol/arducontrol.c
+++ b/arducontrol/arducontrol.c
@@ -11,6 +11,10 @@ Connections for Pololu high-powered motor driver:
 D2 <-> DIR
 D3 <-> PWM
 
+ADC connections:
+ADC0 - current sensor (adjusted for 185 mV/A, centered at Vcc/2)
+ADC1 - input voltage (adjusted for divisor of 11)
+
 This is not a complete control device.  Rather, it is a low-level bus driver,
 intended to be controlled with a computer program.  In particular, no state is
 kept about locomotives or solenoids.  It is up to the controlling program to
@@ -30,6 +34,7 @@ blocks until the operation completes.  The command returns as soon as sending
 its data to the track can start.
 */
 #include <avr/io.h>
+#include "adc.h"
 #include "commands.h"
 #include "motorola.h"
 #include "packet.h"
@@ -50,6 +55,18 @@ volatile uint8_t recv_overrun = 0;
 uint8_t cmd_buf[15];
 uint8_t cmd_length;
 
+uint16_t track_current_samples[16] = { 0 };
+uint8_t track_current_head = 0;
+volatile uint16_t track_current_sum = 0;
+uint16_t overcurrent_limit = 1000<<4;
+uint8_t overcurrent_sent = 0;
+
+uint16_t input_voltage_samples[16] = { 0 };
+uint8_t input_voltage_head = 0;
+volatile uint16_t input_voltage_sum = 0;
+
+volatile uint8_t adc_state = 0;
+
 void process_commands();
 uint8_t process_command();
 
@@ -60,6 +77,7 @@ int main()
 
 	serial_init(9600);
 	timer_start_hz(0, 80000, 1);
+	adc_init();
 
 	sei();
 
@@ -73,6 +91,23 @@ int main()
 		}
 		if(recv_fill>0)
 			process_commands();
+		if(!(adc_state&1))
+		{
+			++adc_state;
+			adc_read_async(adc_state>>1);
+		}
+		if(track_current_sum>overcurrent_limit)
+		{
+			PORTD &= ~0x08;
+			if(!overcurrent_sent)
+			{
+				overcurrent_sent = 1;
+				serial_write(0xFE);
+				serial_write(OVERCURRENT);
+			}
+		}
+		else
+			overcurrent_sent = 0;
 	}
 
 	return 0;
@@ -152,6 +187,38 @@ uint8_t process_command()
 		else
 			PORTD &= ~0x08;
 	}
+	else if(cmd_buf[0]==READ_TRACK_CURRENT)
+	{
+		if(cmd_length!=1)
+			return LENGTH_ERROR;
+
+		serial_write(0xFC);
+		serial_write(TRACK_CURRENT);
+		uint16_t value = track_current_sum>>4;
+		serial_write(value>>8);
+		serial_write(value);
+	}
+	else if(cmd_buf[0]==SET_OVERCURRENT_LIMIT)
+	{
+		if(cmd_length!=3)
+			return LENGTH_ERROR;
+
+		if(cmd_buf[1]&0xF0)
+			return INVALID_VALUE;
+
+		overcurrent_limit = (cmd_buf[1]<<12) | (cmd_buf[2]<<4);
+	}
+	else if(cmd_buf[0]==READ_INPUT_VOLTAGE)
+	{
+		if(cmd_length!=1)
+			return LENGTH_ERROR;
+
+		serial_write(0xFC);
+		serial_write(INPUT_VOLTAGE);
+		uint16_t value = (input_voltage_sum>>3)*5;
+		serial_write(value>>8);
+		serial_write(value);
+	}
 	else if(cmd_buf[0]==MOTOROLA_SPEED || cmd_buf[0]==MOTOROLA_SPEED_DIRECTION || cmd_buf[0]==MOTOROLA_SPEED_FUNCTION)
 	{
 		if(cmd_length!=4)
@@ -287,3 +354,41 @@ static inline void tick()
 }
 
 TIMER_SET_CALLBACK(0, tick)
+
+static inline void adc_complete(uint16_t value)
+{
+	if(adc_state==1)
+	{
+		// Convert to milliamps: (v*5/1024-2.5)*1000/0.185
+		if(value<512)  // Ignore negative current readings
+			value = 0;
+		else if(value>663)  // Limit range so averaging won't overflow
+			value = 4000;
+		else
+			value = (value-512)*132/5;
+
+		uint8_t i = track_current_head;
+		track_current_sum -= track_current_samples[i];
+		track_current_samples[i] = value;
+		track_current_sum += value;
+		track_current_head = (i+1)&15;
+	}
+	else if(adc_state==3)
+	{
+		// Convert to centivolts: (v*5/1024)*100*11
+		if(value>744) // Limit range so averaging won't overflow
+			value = 4000;
+		else
+			value = value*43/8;
+
+		uint8_t i = input_voltage_head;
+		input_voltage_sum -= input_voltage_samples[i];
+		input_voltage_samples[i] = value;
+		input_voltage_sum += value;
+		input_voltage_head = (i+1)&15;
+	}
+
+	++adc_state;
+}
+
+ADC_SET_CALLBACK(adc_complete)
diff --git a/arducontrol/commands.h b/arducontrol/commands.h
index bbd8dc8..64cbe54 100644
--- a/arducontrol/commands.h
+++ b/arducontrol/commands.h
@@ -5,6 +5,9 @@ enum Command
 {
 	POWER_ON = 0x01,
 	POWER_OFF = 0x02,
+	READ_TRACK_CURRENT = 0x03,
+	SET_OVERCURRENT_LIMIT = 0x04,
+	READ_INPUT_VOLTAGE = 0x05,
 	MOTOROLA_SPEED = 0x11,
 	MOTOROLA_REVERSE = 0x12,
 	MOTOROLA_SPEED_DIRECTION = 0x13,
@@ -15,7 +18,10 @@ enum Command
 	FRAMING_ERROR = 0x82,
 	INVALID_COMMAND = 0x83,
 	LENGTH_ERROR = 0x84,
-	INVALID_VALUE = 0x85
+	INVALID_VALUE = 0x85,
+	OVERCURRENT = 0xA0,
+	TRACK_CURRENT = 0xC0,
+	INPUT_VOLTAGE = 0xC1
 };
 
 #endif