Speedometer - Page 2 - Electronic Circuits Projects Diagrams Free

gramo · 10th March 2007, 07:16 AM

There were a couple of things that could have been improved in your program;

- many compilers cant handle cross variable type operations with floats
- you were not polling the info before it was displayed (PIC's work extremely fast, esp @ 20Mhz, and if the value has not changed, why re-write it too the display?
- There is no need to re-write "KM/Hr" over and over
- ALL_DIGITAL = True is a Compiler setting, no need to throw it in the main loop of the program

I modified it a little (you will have to change over the RS and E pins as I've swapped them over - force of habbit as that way they are all connected straight onto the PIC)

Watch the circuit in action here

Code:

Device 16F876A
Declare XTAL 20

Config XT_OSC , WDT_OFF , PWRTE_ON , BODEN_OFF , LVP_OFF , CPD_OFF, CP_OFF , DEBUG_OFF

ALL_DIGITAL = TRUE

Declare LCD_TYPE 0
Declare LCD_DTPIN PORTB.4
Declare LCD_ENPIN PORTB.3
Declare LCD_RSPIN PORTB.2
Declare LCD_INTERFACE 4
Declare LCD_LINES 2

Dim KMH As Float
Dim Temp_Float As Float
Dim KMHT As DWord
Dim KMH_Last As DWord

TRISC.0 = 1

DelayMS 1000
Cls

Print At 1,5, "KM/Hr"
KMHT = 0

Start:

        KMHT = Counter PORTC.0, 250
	
	If KMHT = 0 Then Goto Display
	
	Temp_Float = KMHT
	Temp_Float = (Temp_Float * 4) * 7.2
        KMH =  Temp_Float / 1000
	KMHT = KMH

Display:
	
	If KMH_Last <> KMHT Then
            Print At 1, 1, DEC3 KMHT
	    KMH_Last = KMHT
	EndIf
    
    GoTo Start

Notice I do all the Float functions with floats - so theres no multiplying a Word (0 - 65535) by decimal numbers (such as 7.2) as the answer will be calulated in Word format, and the deciamls will be dropped..

I've used a DWord for KMHT as some of the values can get quite high, and this allows storage of extremely large whole numbers. The Data from KMH is transferred to KMHT so that the decimals are dropped, and to allow the DEC3 modifier to always display three whole numbers i.e. 010, 060, 122 not 10.1, 60.5, 122.9 (theres no need to see the decimal place for speed)

7.2 was calulated by just doing the math before hand (0.002 * 3600)

I threw in the config lines just out of force of habbit

Hope this helps improve the program a little

Kiko · 10th March 2007, 02:37 PM

Quote:

Originally Posted by gramo

There were a couple of things that could have been improved in your program;

- many compilers cant handle cross variable type operations with floats
- you were not polling the info before it was displayed (PIC's work extremely fast, esp @ 20Mhz, and if the value has not changed, why re-write it too the display?
- There is no need to re-write "KM/Hr" over and over
- ALL_DIGITAL = True is a Compiler setting, no need to throw it in the main loop of the program

I modified it a little (you will have to change over the RS and E pins as I've swapped them over - force of habbit as that way they are all connected straight onto the PIC)

Watch the circuit in action here

Code:

Device 16F876A
Declare XTAL 20

Config XT_OSC , WDT_OFF , PWRTE_ON , BODEN_OFF , LVP_OFF , CPD_OFF, CP_OFF , DEBUG_OFF

ALL_DIGITAL = TRUE

Declare LCD_TYPE 0
Declare LCD_DTPIN PORTB.4
Declare LCD_ENPIN PORTB.3
Declare LCD_RSPIN PORTB.2
Declare LCD_INTERFACE 4
Declare LCD_LINES 2

Dim KMH As Float
Dim Temp_Float As Float
Dim KMHT As DWord
Dim KMH_Last As DWord

TRISC.0 = 1

DelayMS 1000
Cls

Print At 1,5, "KM/Hr"
KMHT = 0

Start:

        KMHT = Counter PORTC.0, 250
	
	If KMHT = 0 Then Goto Display
	
	Temp_Float = KMHT
	Temp_Float = (Temp_Float * 4) * 7.2
        KMH =  Temp_Float / 1000
	KMHT = KMH

Display:
	
	If KMH_Last <> KMHT Then
            Print At 1, 1, DEC3 KMHT
	    KMH_Last = KMHT
	EndIf
    
    GoTo Start

Notice I do all the Float functions with floats - so theres no multiplying a Word (0 - 65535) by decimal numbers (such as 7.2) as the answer will be calulated in Word format, and the deciamls will be dropped..

I've used a DWord for KMHT as some of the values can get quite high, and this allows storage of extremely large whole numbers. The Data from KMH is transferred to KMHT so that the decimals are dropped, and to allow the DEC3 modifier to always display three whole numbers i.e. 010, 060, 122 not 10.1, 60.5, 122.9 (theres no need to see the decimal place for speed)

7.2 was calulated by just doing the math before hand (0.002 * 3600)

I threw in the config lines just out of force of habbit

Hope this helps improve the program a little

OK sir I got it, as I'm not a programmer nor a enginner any help with a exemple like you did are welcome. Thank you very much...

And like I post before this is not the only problem I have because I want to make a gear indicator and this is the worse problem I'm having and I think you can help with this issue. I'll try to explain the problem (in english) in another post. Thank you again.

Kiko · 10th March 2007, 03:11 PM

My Suzuki bike has an OEM gear position sensor (GPS) that gives the output voltage as follow:

1st gear = 1.782v
2nd gear = 2.242v
3rd gear = 2.960v
4th gear = 3.630v
5th gear = 4.310v
6th gear = 4.660v
Neutral = 5.000v

My circuit have a voltage divider using RA0 as input and with this setup I can do a routine to show me the gear I'm on the LCD. But the problem start to grow up when I start the engine because the voltage that come from the GPS is not the same when just the ignition is on and in the 6th gear for exemple I have a voltage that vary from 4 to 5v and them the the LCD shows sometimes 5th gear neutral and 6th gear when I'm in the 6th gear.

Follows are the voltages I've taken running the bike:

1st gear = 1.243v to 2.586v
2nd gear = 2.124v to 3.210v
3rd gear = 3.178v to 3.486v
4th gear = 3.633v to 4.400v
5th gear = 4.215v to 4.887v
6th gear = 4.461v to 4.942v
Neutral = 4.678v to 5.245v

The idea then is to write a routine that whem I'm in 6th (betwen 4.461 and 4.942) the program lock only the reading (6th gear on LCD) but still monitoring the voltages and jump to another gear without interfere with each other.

I don't know if I could explain... But any help will be wellcome.

gramo · 10th March 2007, 03:20 PM

Quote:

Originally Posted by Kiko

My Suzuki bike has an OEM gear position sensor (GPS) that gives the output voltage as follow:

1st gear = 1.782v
2nd gear = 2.242v
3rd gear = 2.960v
4th gear = 3.630v
5th gear = 4.310v
6th gear = 4.660v
Neutral = 5.000v

Follows are the voltages I've taken running the bike:

1st gear = 1.243v to 2.586v
2nd gear = 2.124v to 3.210v
3rd gear = 3.178v to 3.486v
4th gear = 3.633v to 4.400v
5th gear = 4.215v to 4.887v
6th gear = 4.461v to 4.942v
Neutral = 4.678v to 5.245v

The idea then is to write a routine that whem I'm in 6th (betwen 4.461 and 4.942) the program lock only the reading (6th gear on LCD) but still monitoring the voltages and jump to another gear without interfere with each other.

I don't know if I could explain... But any help will be wellcome.

Hmm, over lapping voltages for different gears, leave it with me, I'm sure with enough samples we could calculate the average that would be a lot closer to the actual manufacture's specifications.. Its 2am here, I'll get on it tomorrow and make another program for you

Kiko · 10th March 2007, 03:51 PM

Quote:

Originally Posted by gramo

Hmm, over lapping voltages for different gears, leave it with me, I'm sure with enough samples we could calculate the average that would be a lot closer to the actual manufacture's specifications.. Its 2am here, I'll get on it tomorrow and make another program for you

Over lapping... I hate this word at this moment (just kidding).

I apreciate your help.

gramo · 11th March 2007, 01:59 AM

All finished, heres the code;

Code:

Device 16F876
Declare XTAL 20

Config XT_OSC , WDT_OFF , PWRTE_ON , BODEN_OFF , LVP_OFF , CPD_OFF, CP_OFF , DEBUG_OFF

Declare LCD_TYPE 0
Declare LCD_DTPIN PORTB.4
Declare LCD_ENPIN PORTB.3
Declare LCD_RSPIN PORTB.2
Declare LCD_INTERFACE 4
Declare LCD_LINES 2

Dim KMH As Float
Dim Temp_Float As Float
Dim KMHT As DWord
Dim KMH_Last As DWord

Dim Result As Word
Dim Total As Float
Dim Last_Result As Float
Dim X As Byte

Symbol _1_Min = 1.243
Symbol _1_Max = 2.355

Symbol _2_Min = 2.356
Symbol _2_Max = 3.194

Symbol _3_Min = 3.195
Symbol _3_Max = 3.709

Symbol _4_Min = 3.710
Symbol _4_Max = 4.307

Symbol _5_Min = 4.308
Symbol _5_Max = 4.674

Symbol _6_Min = 4.675
Symbol _6_Max = 4.810

Symbol _N_Min = 4.811
Symbol _N_Max = 5.245

TRISC.0 = 1

DelayMS 1000
Cls

Print At 1,5, "KM/Hr"
KMHT = 0

TRISA.0 = 1
ADCON1 = %10000000 			' Set analogue input, Vref is Vdd

Start:

	Result = 0
	Total = 0
	X = 0
	
	Repeat
	
		  Result = ADIN 0
		  Result = Result * 2
		  Total = Total + Result
		  
		  Inc X
	
	Until X = 15
	
	Total = Total / 15
	
	Total = Total * 5 / 1023
	
	Select Total
		   Case _1_Min To _1_Max
		   		Print At 2, 1, "1st Gear ", DEC3 Total, "V"
		   Case _2_Min To _2_Max
		   		Print At 2, 1, "2nd Gear ", DEC3 Total, "V"
		   Case _3_Min To _3_Max
		   		Print At 2, 1, "3rd Gear ", DEC3 Total, "V"
		   Case _4_Min To _4_Max
		   		Print At 2, 1, "4th Gear ", DEC3 Total, "V"
		   Case _5_Min To _5_Max
		   		Print At 2, 1, "5th Gear ", DEC3 Total, "V"
		   Case _6_Min To _6_Max
		   		Print At 2, 1, "6th Gear ", DEC3 Total, "V"
		   Case _N_Min To _N_Max
   		   		Print At 2, 1, "Neutral  ", DEC3 Total, "V"
		   Case Else
   		   		Print At 2, 1, "Unknown  ", DEC3 Total, "V"
	EndSelect
				
        KMHT = Counter PORTC.0, 250
	
	If KMHT = 0 Then Goto Display
	
	Temp_Float = KMHT
	Temp_Float = Temp_Float * 4 * 7.2
        KMH =  Temp_Float / 1000
	KMHT = KMH

Display:
	
	If KMH_Last <> KMHT Then
            Print At 1, 1, DEC3 KMHT
	    KMH_Last = KMHT
	EndIf
    
    GoTo Start

You can modify the Symbols Containing the Min and Max voltage values that are allowed for each gear.

The program can probably be tweaked - eg I left the volt display on there for debugging and you can remove it once you feel happy you know all of the volages are correct.

Watch the circuit in action here The SIM appears laggy as there are 7 Signal gererators in use. It will be much faster in real time.

gramo · 11th March 2007, 03:05 AM

You might be asking why on earth I used a voltage divider in the circuit - its because in Neutral, the were voltages over 5V, and PIC's don’t like that!

So to keep everything to operating standards, the voltage divider is just halving the sample voltage; eg, 5.5V from the gear selector output will now be sampled as 2.25V by the PIC. The program scales it back up mathematically

Kiko · 11th March 2007, 04:24 AM

Quote:

Originally Posted by gramo

All finished, heres the code;

Code:

Device 16F876
Declare XTAL 20

Config XT_OSC , WDT_OFF , PWRTE_ON , BODEN_OFF , LVP_OFF , CPD_OFF, CP_OFF , DEBUG_OFF

Declare LCD_TYPE 0
Declare LCD_DTPIN PORTB.4
Declare LCD_ENPIN PORTB.3
Declare LCD_RSPIN PORTB.2
Declare LCD_INTERFACE 4
Declare LCD_LINES 2

Dim KMH As Float
Dim Temp_Float As Float
Dim KMHT As DWord
Dim KMH_Last As DWord

Dim Result As Word
Dim Total As Float
Dim Last_Result As Float
Dim X As Byte

Symbol _1_Min = 1.243
Symbol _1_Max = 2.355

Symbol _2_Min = 2.356
Symbol _2_Max = 3.194

Symbol _3_Min = 3.195
Symbol _3_Max = 3.709

Symbol _4_Min = 3.710
Symbol _4_Max = 4.307

Symbol _5_Min = 4.308
Symbol _5_Max = 4.674

Symbol _6_Min = 4.675
Symbol _6_Max = 4.810

Symbol _N_Min = 4.811
Symbol _N_Max = 5.245

TRISC.0 = 1

DelayMS 1000
Cls

Print At 1,5, "KM/Hr"
KMHT = 0

TRISA.0 = 1
ADCON1 = %10000000 			' Set analogue input, Vref is Vdd

Start:

	Result = 0
	Total = 0
	X = 0
	
	Repeat
	
		  Result = ADIN 0
		  Result = Result * 2
		  Total = Total + Result
		  
		  Inc X
	
	Until X = 15
	
	Total = Total / 15
	
	Total = Total * 5 / 1023
	
	Select Total
		   Case _1_Min To _1_Max
		   		Print At 2, 1, "1st Gear ", DEC3 Total, "V"
		   Case _2_Min To _2_Max
		   		Print At 2, 1, "2nd Gear ", DEC3 Total, "V"
		   Case _3_Min To _3_Max
		   		Print At 2, 1, "3rd Gear ", DEC3 Total, "V"
		   Case _4_Min To _4_Max
		   		Print At 2, 1, "4th Gear ", DEC3 Total, "V"
		   Case _5_Min To _5_Max
		   		Print At 2, 1, "5th Gear ", DEC3 Total, "V"
		   Case _6_Min To _6_Max
		   		Print At 2, 1, "6th Gear ", DEC3 Total, "V"
		   Case _N_Min To _N_Max
   		   		Print At 2, 1, "Neutral  ", DEC3 Total, "V"
		   Case Else
   		   		Print At 2, 1, "Unknown  ", DEC3 Total, "V"
	EndSelect
				
        KMHT = Counter PORTC.0, 250
	
	If KMHT = 0 Then Goto Display
	
	Temp_Float = KMHT
	Temp_Float = Temp_Float * 4 * 7.2
        KMH =  Temp_Float / 1000
	KMHT = KMH

Display:
	
	If KMH_Last <> KMHT Then
            Print At 1, 1, DEC3 KMHT
	    KMH_Last = KMHT
	EndIf
    
    GoTo Start

You can modify the Symbols Containing the Min and Max voltage values that are allowed for each gear.

The program can probably be tweaked - eg I left the volt display on there for debugging and you can remove it once you feel happy you know all of the volages are correct.

Watch the circuit in action here The SIM appears laggy as there are 7 Signal gererators in use. It will be much faster in real time.

Looks great for me, I'll try to understand what you did and run it on the bench and then on the bike. But I can tell you that for some reason that I don't know yet the speedo when I install on the bike have a strange behavior, I mean, the speed readings are not accurated, but it's on the bench when I simulate the speed with signal generator, tomorrow if my wife permit, I'll troubleshoot my bike's voltage regulator and generator.

I apreciate you help indeed and thank you very much

ps: If you have any more ideas please let me know.

Kiko · 11th March 2007, 04:28 AM

Quote:

Originally Posted by gramo

You might be asking why on earth I used a voltage divider in the circuit - its because in Neutral, the were voltages over 5V, and PIC's don’t like that!

So to keep everything to operating standards, the voltage divider is just halving the sample voltage; eg, 5.5V from the gear selector output will now be sampled as 2.25V by the PIC. The program scales it back up mathematically

OK I understand and I have it in my circuit, thank you.

Pommie · 11th March 2007, 05:36 AM

Does the gear voltage vary with engine RPM. If so, the voltage may be relative to the battery voltage and you may be able to fix it by setting the ADC reference voltage to a division of the battery voltage.

BTW, have you changed to a schmitt trigger input and if you have, did it work?

Mike.

gramo · 11th March 2007, 06:46 AM

I used PORTC.0 as the RPM sensor, all of the Pins have a built in schmitt trigger on PORTC, so I hope that helps him out

Kiko · 11th March 2007, 03:35 PM

Quote:

Originally Posted by Pommie

Does the gear voltage vary with engine RPM. If so, the voltage may be relative to the battery voltage and you may be able to fix it by setting the ADC reference voltage to a division of the battery voltage.

BTW, have you changed to a schmitt trigger input and if you have, did it work?

Mike.

Unfortunately not and I have changed de input port to RC7 and still the same. I think I have some kind of noise that come from the generator because when the engine is not runnig or the circuit is on the bench it works ok. I didn't have time to try the gramo routine yet and to troubleshoot the generator.

I will post the news later just for information. Thank you very much.

Kiko · 11th March 2007, 04:30 PM

FYI attached is the circuit I'm using.

I increased the value of C5 and C7 to try to filter any noise (didn't work).

I've placed a 10k resistor (pull-down) on PORTC7 then I removed because it killed the signal to the original bike's speedometer.

danci1973 · 12th March 2007, 07:22 PM

I think your problem is in the ground - what ground did you use when you measured the voltages? I think you should use the black/white wire on the gear position switch connector, not just any ground on the bike.

Attached is a picture of how I think the Suzuki gear position switch is wired.

D.

Kiko · 12th March 2007, 11:00 PM

Quote:

Originally Posted by gramo

All finished, heres the code;

Code:

Device 16F876
Declare XTAL 20

Config XT_OSC , WDT_OFF , PWRTE_ON , BODEN_OFF , LVP_OFF , CPD_OFF, CP_OFF , DEBUG_OFF

Declare LCD_TYPE 0
Declare LCD_DTPIN PORTB.4
Declare LCD_ENPIN PORTB.3
Declare LCD_RSPIN PORTB.2
Declare LCD_INTERFACE 4
Declare LCD_LINES 2

Dim KMH As Float
Dim Temp_Float As Float
Dim KMHT As DWord
Dim KMH_Last As DWord

Dim Result As Word
Dim Total As Float
Dim Last_Result As Float
Dim X As Byte

Symbol _1_Min = 1.243
Symbol _1_Max = 2.355

Symbol _2_Min = 2.356
Symbol _2_Max = 3.194

Symbol _3_Min = 3.195
Symbol _3_Max = 3.709

Symbol _4_Min = 3.710
Symbol _4_Max = 4.307

Symbol _5_Min = 4.308
Symbol _5_Max = 4.674

Symbol _6_Min = 4.675
Symbol _6_Max = 4.810

Symbol _N_Min = 4.811
Symbol _N_Max = 5.245

TRISC.0 = 1

DelayMS 1000
Cls

Print At 1,5, "KM/Hr"
KMHT = 0

TRISA.0 = 1
ADCON1 = %10000000 			' Set analogue input, Vref is Vdd

Start:

	Result = 0
	Total = 0
	X = 0
	
	Repeat
	
		  Result = ADIN 0
		  Result = Result * 2
		  Total = Total + Result
		  
		  Inc X
	
	Until X = 15
	
	Total = Total / 15
	
	Total = Total * 5 / 1023
	
	Select Total
		   Case _1_Min To _1_Max
		   		Print At 2, 1, "1st Gear ", DEC3 Total, "V"
		   Case _2_Min To _2_Max
		   		Print At 2, 1, "2nd Gear ", DEC3 Total, "V"
		   Case _3_Min To _3_Max
		   		Print At 2, 1, "3rd Gear ", DEC3 Total, "V"
		   Case _4_Min To _4_Max
		   		Print At 2, 1, "4th Gear ", DEC3 Total, "V"
		   Case _5_Min To _5_Max
		   		Print At 2, 1, "5th Gear ", DEC3 Total, "V"
		   Case _6_Min To _6_Max
		   		Print At 2, 1, "6th Gear ", DEC3 Total, "V"
		   Case _N_Min To _N_Max
   		   		Print At 2, 1, "Neutral  ", DEC3 Total, "V"
		   Case Else
   		   		Print At 2, 1, "Unknown  ", DEC3 Total, "V"
	EndSelect
				
        KMHT = Counter PORTC.0, 250
	
	If KMHT = 0 Then Goto Display
	
	Temp_Float = KMHT
	Temp_Float = Temp_Float * 4 * 7.2
        KMH =  Temp_Float / 1000
	KMHT = KMH

Display:
	
	If KMH_Last <> KMHT Then
            Print At 1, 1, DEC3 KMHT
	    KMH_Last = KMHT
	EndIf
    
    GoTo Start

You can modify the Symbols Containing the Min and Max voltage values that are allowed for each gear.

The program can probably be tweaked - eg I left the volt display on there for debugging and you can remove it once you feel happy you know all of the volages are correct.

Watch the circuit in action here The SIM appears laggy as there are 7 Signal gererators in use. It will be much faster in real time.

How did you find the constants assigned below?

Symbol _1_Min = 1.243
Symbol _1_Max = 2.355

Symbol _2_Min = 2.356
Symbol _2_Max = 3.194

Symbol _3_Min = 3.195
Symbol _3_Max = 3.709

Symbol _4_Min = 3.710
Symbol _4_Max = 4.307

Symbol _5_Min = 4.308
Symbol _5_Max = 4.674

Symbol _6_Min = 4.675
Symbol _6_Max = 4.810

Symbol _N_Min = 4.811
Symbol _N_Max = 5.245

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Anyone make their own top gear indicator? - Page 8 - Stromtrooper.com	This thread	Refback	21st May 2008 09:22 PM
Anyone make their own top gear indicator? - Page 8 - Stromtrooper.com	This thread	Refback	21st May 2008 04:11 AM
Anyone make their own top gear indicator? - Page 8 - Stromtrooper.com	This thread	Refback	20th May 2008 04:52 AM
RENAULT 9-11 KULÜBÜ - Dijital km göstergesi ?	This thread	Refback	18th May 2008 12:36 PM

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10th March 2007, 07:16 AM	(permalink)
gramo	There were a couple of things that could have been improved in your program; - many compilers cant handle cross variable type operations with floats - you were not polling the info before it was displayed (PIC's work extremely fast, esp @ 20Mhz, and if the value has not changed, why re-write it too the display? - There is no need to re-write "KM/Hr" over and over - ALL_DIGITAL = True is a Compiler setting, no need to throw it in the main loop of the program I modified it a little (you will have to change over the RS and E pins as I've swapped them over - force of habbit as that way they are all connected straight onto the PIC) Watch the circuit in action here Code: Device 16F876A Declare XTAL 20 Config XT_OSC , WDT_OFF , PWRTE_ON , BODEN_OFF , LVP_OFF , CPD_OFF, CP_OFF , DEBUG_OFF ALL_DIGITAL = TRUE Declare LCD_TYPE 0 Declare LCD_DTPIN PORTB.4 Declare LCD_ENPIN PORTB.3 Declare LCD_RSPIN PORTB.2 Declare LCD_INTERFACE 4 Declare LCD_LINES 2 Dim KMH As Float Dim Temp_Float As Float Dim KMHT As DWord Dim KMH_Last As DWord TRISC.0 = 1 DelayMS 1000 Cls Print At 1,5, "KM/Hr" KMHT = 0 Start: KMHT = Counter PORTC.0, 250 If KMHT = 0 Then Goto Display Temp_Float = KMHT Temp_Float = (Temp_Float * 4) * 7.2 KMH = Temp_Float / 1000 KMHT = KMH Display: If KMH_Last <> KMHT Then Print At 1, 1, DEC3 KMHT KMH_Last = KMHT EndIf GoTo Start Notice I do all the Float functions with floats - so theres no multiplying a Word (0 - 65535) by decimal numbers (such as 7.2) as the answer will be calulated in Word format, and the deciamls will be dropped.. I've used a DWord for KMHT as some of the values can get quite high, and this allows storage of extremely large whole numbers. The Data from KMH is transferred to KMHT so that the decimals are dropped, and to allow the DEC3 modifier to always display three whole numbers i.e. 010, 060, 122 not 10.1, 60.5, 122.9 (theres no need to see the decimal place for speed) 7.2 was calulated by just doing the math before hand (0.002 * 3600) I threw in the config lines just out of force of habbit Hope this helps improve the program a little __________________ Spency. PIC Micro's - Your mind is the limit PIC's and interfacing with other devices - a PIC Basic Guide @ digital-diy.net Last edited by gramo; 10th March 2007 at 08:43 AM.

10th March 2007, 03:11 PM	(permalink)
Kiko	My Suzuki bike has an OEM gear position sensor (GPS) that gives the output voltage as follow: 1st gear = 1.782v 2nd gear = 2.242v 3rd gear = 2.960v 4th gear = 3.630v 5th gear = 4.310v 6th gear = 4.660v Neutral = 5.000v My circuit have a voltage divider using RA0 as input and with this setup I can do a routine to show me the gear I'm on the LCD. But the problem start to grow up when I start the engine because the voltage that come from the GPS is not the same when just the ignition is on and in the 6th gear for exemple I have a voltage that vary from 4 to 5v and them the the LCD shows sometimes 5th gear neutral and 6th gear when I'm in the 6th gear. Follows are the voltages I've taken running the bike: 1st gear = 1.243v to 2.586v 2nd gear = 2.124v to 3.210v 3rd gear = 3.178v to 3.486v 4th gear = 3.633v to 4.400v 5th gear = 4.215v to 4.887v 6th gear = 4.461v to 4.942v Neutral = 4.678v to 5.245v The idea then is to write a routine that whem I'm in 6th (betwen 4.461 and 4.942) the program lock only the reading (6th gear on LCD) but still monitoring the voltages and jump to another gear without interfere with each other. I don't know if I could explain... But any help will be wellcome.

11th March 2007, 03:05 AM	(permalink)
gramo	You might be asking why on earth I used a voltage divider in the circuit - its because in Neutral, the were voltages over 5V, and PIC's don’t like that! So to keep everything to operating standards, the voltage divider is just halving the sample voltage; eg, 5.5V from the gear selector output will now be sampled as 2.25V by the PIC. The program scales it back up mathematically __________________ Spency. PIC Micro's - Your mind is the limit PIC's and interfacing with other devices - a PIC Basic Guide @ digital-diy.net

11th March 2007, 05:36 AM	(permalink)
Pommie	Does the gear voltage vary with engine RPM. If so, the voltage may be relative to the battery voltage and you may be able to fix it by setting the ADC reference voltage to a division of the battery voltage. BTW, have you changed to a schmitt trigger input and if you have, did it work? Mike.

11th March 2007, 06:46 AM	(permalink)
gramo	I used PORTC.0 as the RPM sensor, all of the Pins have a built in schmitt trigger on PORTC, so I hope that helps him out __________________ Spency. PIC Micro's - Your mind is the limit PIC's and interfacing with other devices - a PIC Basic Guide @ digital-diy.net