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Old Feb 15, 2013, 11:49 PM
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help esc brushed for airplan

Hi everyone
I search internet some circuit control motor brushed
and I found here http://www.bhabbott.net.nz/ICS100Li.html



but I meet difficulty,motor turns max when joystick at position 50% !!!!

I see code ASM throttle min 1.2ms and max 1.8ms.
perhaps my TX and RX is not in this range
how to change?setting limits max and min for each tx and rx?
thanks
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Old Feb 16, 2013, 04:45 AM
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please help me everyone
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Old Feb 16, 2013, 11:29 AM
"Unnecessary Necessity"
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What Tx and Rx are you using, and how are the trims set?
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Old Feb 16, 2013, 01:22 PM
Really?!?
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Could it be as simple as adjusting your throttle ATV back some?

Chris
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Old Feb 16, 2013, 08:08 PM
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hi coriolan and ChrisS
I use TX and RX Esky 4 ch
maybe circuit not setting throttle min and max as to Esc brushless ?
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Old Feb 16, 2013, 11:59 PM
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this is code and schematic of Bruce abbot

change program is hard,because 12f675 have not pin creat PWM , should replace by 12f683 (1 pin PWM ) or 12f617 (2 pin PWM )
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Old Feb 17, 2013, 05:15 AM
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Quote:
Originally Posted by Jame David View Post
hi coriolan and ChrisS
I use TX and RX Esky 4 ch
I tested an E-Sky 0404 transmitter and it was producing about 1.1~1.9mS, with ~1.5mS at center stick.

If you have an oscilloscope then it should be easy to check the pulse width. If you don't have a scope then you could try using a software oscilloscope that works with your soundcard, eg. sound card oscilloscope V1.41 by Christian Zeitnitz.

If the pulse width is OK then you may have accidentally erased the OSCCAL byte in your PIC (located at address 0x3ff). Try different values ranging from 0x00 to 0xff (0x80 is center frequency).
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Old Feb 17, 2013, 08:48 AM
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Quote:
Originally Posted by Bruce Abbott View Post
I tested an E-Sky 0404 transmitter and it was producing about 1.1~1.9mS, with ~1.5mS at center stick.

If you have an oscilloscope then it should be easy to check the pulse width. If you don't have a scope then you could try using a software oscilloscope that works with your soundcard, eg. sound card oscilloscope V1.41 by Christian Zeitnitz.

If the pulse width is OK then you may have accidentally erased the OSCCAL byte in your PIC (located at address 0x3ff). Try different values ranging from 0x00 to 0xff (0x80 is center frequency).
Thank you,I will try .

but I do not know setting OSCCAL byte in PIC. It can change limit signal from 1.0 - 2.0ms ?
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Old Feb 17, 2013, 03:16 PM
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Quote:
Originally Posted by Jame David View Post
but I do not know setting OSCCAL byte in PIC. It can change limit signal from 1.0 - 2.0ms ?
The OSCCAL byte is used to 'tune' the PIC to the correct clock frequency. Due to manufacturing tolerances every individual chip is different, so Microchip measures the clock frequency and programs the instruction 'RETLW xx' (where xx = the specific OSCAL byte for that chip) into the last program location. In hex this appears as two bytes '34 xx' at memory location 03FF.

Changing OSCCAL can vary the system clock frequency by as much as 40%. If the clock is fast then the PIC will think the throttle signal is higher than reality. For example, if the PIC is running at 4.8MHz (20% fast) then a pulse width of 1.5mS (mid throttle) will be detected as 1.8mS (high throttle!).

To see if this might be your problem, try the 3 hex files below. The first one sets OSCCAL to 0x00, the second one sets it to 0x80, and the last one sets it to 0xFF.
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Old Apr 01, 2013, 12:57 AM
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Quote:
Originally Posted by Bruce Abbott View Post
The OSCCAL byte is used to 'tune' the PIC to the correct clock frequency. Due to manufacturing tolerances every individual chip is different, so Microchip measures the clock frequency and programs the instruction 'RETLW xx' (where xx = the specific OSCAL byte for that chip) into the last program location. In hex this appears as two bytes '34 xx' at memory location 03FF.

Changing OSCCAL can vary the system clock frequency by as much as 40%. If the clock is fast then the PIC will think the throttle signal is higher than reality. For example, if the PIC is running at 4.8MHz (20% fast) then a pulse width of 1.5mS (mid throttle) will be detected as 1.8mS (high throttle!).


.
Circuit work, but serious problems occur when the temperature increases.
Pulse positions are not as same at the beginning

1.5ms ----> max PWM .
 
I think, high temperature, which changes the oscillation frequency in the PIC

I see datasheet, pins 2 and 3 can be installed quartz. You can help me set quartz 4mhz pic ?

I used two your version here

http://www.bhabbott.net.nz/esc.html

http://www.bhabbott.net.nz/ICS100Li.html


thanks a lot
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Old Apr 01, 2013, 02:17 AM
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I have modified the internal oscillator as in guide of this site

http://picprojects.org.uk/projects/recal/recal.htm





but when the temperature is change, pic working wrong.

I think there must be external quartz 4mhz
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Old Apr 01, 2013, 03:12 AM
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Quote:
Originally Posted by Jame David View Post
Circuit work, but serious problems occur when the temperature increases.
Pulse positions are not as same at the beginning

1.5ms ----> max PWM .
The internal oscillator is normally very stable. Either you have a marginal chip or it is getting very hot!

You can attach a crystal or ceramic resonator to pins 2 and 3. If you use a 3 terminal resonator then you won't need any capacitors.

The clock mode must also be changed to High Speed Crystal/Resonator, by replacing the config value "_INTRC_OSC_NOCLKOUT" with "_HS_OSC". I have attached a hex file with that change incorporated.
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Old Apr 01, 2013, 09:45 AM
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Thank Bruce

perhaps I have misunderstood about temperature to affect the PIC
I do not know PIC 12f675 which I bought, can be fake chips ( i buy from china )
or another reason.?

I suspect my program load device that caused the error OSSCAL VALUE

I will try to use external quartz 4mhz with your new code
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Old Apr 18, 2013, 08:19 PM
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hello Bruce

I checked the hex file, seems 12f 675 read pulse signals are not good

i use LED display PWM
file hex 128 ----> 12f675 read 1030

file hex 255 ----->12f675 read 820

file hex crystal 4mhz ------>12f675 read 1110


read pulse position changes continuously unstable
I do not understand what has happened
begins at 1.2ms, and end 1.8ms .I never seen

I use circuit test signal pulse of Philip sun here : http://ilufa.orgfree.com/MT_E.htm

equipment load program by port COM 1
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Old Apr 19, 2013, 07:02 PM
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you should stop using the version for 12f675, and converted to version 12f617

here is version 12f617 for car http://www.rcgroups.com/forums/showt...1747098&page=4



Quote:
#define ARM ; Throttle will not operate until set to neutral position
#define FAILSAFE ; Throttle moves towards neutral when bad pulses received
#define ArmPulsesReqd 25 ; number of good servo pulses required to arm thottle
;#define LIPO ; lithium polymer battery
;#define LVC ; GP1 is battery voltage input
#define STATUSLED ; GP1 Status LED
;#define BRAKELED ; GP1 is brake LED
#define REVERSEBRAKE ; braking in reverse
#define SLOW ; rate-limited throttle response
#define STEP 10 ; maximum PWM change per frame (rate-limited only)
#define MAXTHROTTLE 1800 ; 1.8mS = full forward throttle position
#define MAXNEUTRAL 1550 ;
#define MIDTHROTTLE 1500 ; 1.45~1.55mS = neutral position
#define MINNEUTRAL 1450 ;
#define MINTHROTTLE 1200 ; 1.2mS = full reverse throttle position
;#define DEADBAND 4 ; deadband (enable this for half-bridge mode)

you need to modify the code for use on aircraft
  remove reverse, brake at 1000, Forward min at 1200 and max 1800
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Last edited by rc my life; Apr 19, 2013 at 07:31 PM.
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