Yet another Evo9 2.4GHz conversion

[mmormota]

I converted my Evo9 to FASST spreaded spectrum radio, using a T6EXA rf pcb and a PIC12F683 uC. Let the pictures tell the story... ;)

The failsafe mode and the range check mode is controlled by the Evo, programmable in the usual way.


"I am not recommending this modification to anybody. I am only reporting what I did and how."

It is working for me, but there are possible errors in the code or the method itself. A malfuction may cause the loss of control, injury etc.

[mmormota]

The source code:
;
; -------------------------------------------------------------------
; | |
; | Interface program for using the Futaba T6EX radio's |
; | FASST Rf pcb in the Multiplex Royal Evo9 radio |
; | |
; -------------------------------------------------------------------
;
; The Futaba FASST pcb needs a special 8 channel ppm input. The length of the 1st positive
; pulse determines if the module transmits on normal or reduced power level.
; 1st pulse:
; 420 usec: normal power
; 440 usec: reduced power, range check mode
; 2nd to 9th pulse:
; 400 usec
; The value of the 8th channel determinies the fail-safe value and mode.
; The failsafe mode means that in case of connection break the 3rd channel output gets the last
; value of the 8th channel.
; If the 8th channel value is 0,9 ms = -110% (on a -100% to +100% scale) then fail-safe is off, the 3rd channel just keeps the
; last valid value.
;
; This firmware made for a PIC12F683 uC. It receives the ppm signal from the Evo9 on GP2 pin5, and sends
; out the the modified pulses on GP0 pin7. (Vdd: pin1 Gnd:pin8 all other pins NC)
; The delay on receiving the pulses and sending them out is negligible, a few usecs only.
;
; The interface has 2 basic modes.
; Mode 1:
; the Evo9 must be in 8 channel mode (8th channel assigned to a function, the 9th is not)
; the interface sends out the pulses to choose the "normal power" mode.
; Mode 2:
; The mode is programmable in the usual way using the 9th. channel. As the range check mode is critical, never
; program it to a normal switch. Use a pushbutton to avoid unwanted reduced power mode during normal flight.
; the Evo9 must be in 9 channel mode (the 9th channels assigned to a function)
; the 9th channel tells to the interface the necessary power mode
; range check mode: set ch9 to 2000 usec or 90% (on a -100% to +100% scale)
; normal power mode: set ch9 to 1000 usec or -90% (on a -100% to +100% scale)
; the interface just receives ch9, but not sends out the 10th pulse, as the FASST pcb needs 8ch ppm

; A possible way to program the modes in the Evo9:
; In the setup menu, assign the H pushbutton to the AUX1 menu.
; In the servo menu, assign ch8 to AUX1. The is the servo/calibrate menu, turn all points to the same value (getting a horizontal line),
; this value is the fail-safe for the 3rd channel. Turn all points to -110% for fail-safe mode off.
; For range check, assign ch9 to AUX1. Turn the end points to -80% and +80%. Push and keep pushed the H button to get range-check mode.
; (the red led blinks to indicate the reduced power mode)
;
list p=12f683
#include P12F683.INC
__CONFIG _MCLRE_OFF&_CP_OFF&_WDT_OFF&_INTRC_OSC_NOCLKOUT

; Bit definitions for the GPIO register and the TRIS register

#DEFINE no_pulse 0 ; no output pulse on irq
#DEFINE norm_power D'420' ; 420 usec, normal power
#DEFINE range_check D'440' ; 440 usec, reduced power
#DEFINE normal_pulse D'400' ; 400 usec, normal 3...9th pulse
#DEFINE ch9_range_min D'1900' ; if 1900 < 9th_channel <2000 it's range check
#DEFINE ch9_range_max D'2050' ; if no 9th channel or the pulse is out of the above range it's normal power mode

;================================================= ==========================
; Macro to create offsets for variables in RAM
;
ByteAddr SET 32 ; user RAM starts here

BYTE MACRO ByteName
ByteName EQU ByteAddr
ByteAddr SET ByteAddr+1
ENDM

; ================================================== ========================
; RAM Variable Definitions
;
BYTE mode ; bit7: the irq sends a message to the main program by clearing the bit
; it means, that an input pwm pulse received
BYTE counter ; time counter, 12usec / step
BYTE pulse_length ; the main program sets it, and the irq creates a pulse according to this value
BYTE first_pulse ; the length of the first pulse according to mode
BYTE startup_counter ; it counts the frames sat startup
BYTE delay_counter



; -------------------------------------------------------------------
; | |
; | Code start |
; | |
; -------------------------------------------------------------------

org 0x000

goto Start ; Start application beyond vector area
org 04h
goto interrupt

; -------------------------------------------------------------------
; | |
; | Main program start |
; | |
; -------------------------------------------------------------------

org 8h
Start:
nop
nop
nop
nop
BCF STATUS,RP0 ;Bank 0
CLRF GPIO ;Init GPIO
MOVLW 07h ;Set GP<2:0> to
MOVWF CMCON0 ;digital I/O
BSF STATUS,RP0 ;Bank 1
CLRF ANSEL ;digital I/O
MOVLW 04h ;Set GP2 as input
MOVWF TRISIO ;and set GP<5,4,3,1,0> as outputs
bsf OSCCON,4 ;switch to 8MHz, default on startup is 4MHz
BCF STATUS,RP0 ;Bank 0
bsf INTCON,INTE


bsf GPIO,0 ; 220 msec high on startup

bsf mode,7
movlw no_pulse
movwf pulse_length
bcf INTCON,INTF
bsf INTCON,GIE

movlw D'72' ; waits for several pulses before start
movwf startup_counter

wait_pulses:
bsf mode,7
wait_0:
btfsc mode,7
goto wait_0

decfsz startup_counter
goto wait_pulses

bcf GPIO,0 ; startup pulse end


default_pulses:
movlw norm_power/4 ; default mode setting: normal power
movwf first_pulse

wait_frame_gap:
bsf mode,7
call time_counter

addlw 0ffh ; if the time_counter reaches 3ms, it comes back with 1
bnz wait_frame_gap ; jumps to wait_frame_gap, if the counter comes back before 3ms

movf first_pulse,w
movwf pulse_length
bsf mode,7
wait_1:
btfsc mode,7
goto wait_1

movf normal_pulse/4
movwf pulse_length
bsf mode,7
wait_2:
btfsc mode,7
goto wait_2

movlw normal_pulse/4
movwf pulse_length
bsf mode,7
wait_3:
btfsc mode,7
goto wait_3

movlw normal_pulse/4
movwf pulse_length
bsf mode,7
wait_4:
btfsc mode,7
goto wait_4

movlw normal_pulse/4
movwf pulse_length
bsf mode,7
wait_5:
btfsc mode,7
goto wait_5

movlw normal_pulse/4
movwf pulse_length
bsf mode,7
wait_6:
btfsc mode,7
goto wait_6

movlw normal_pulse/4
movwf pulse_length
bsf mode,7
wait_7:
btfsc mode,7
goto wait_7

movlw normal_pulse/4
movwf pulse_length
bsf mode,7
wait_8:
btfsc mode,7
goto wait_8

movlw normal_pulse/4
movwf pulse_length
bsf mode,7
wait_9:
btfsc mode,7
goto wait_9

wait_10:
movlw no_pulse/4
movwf pulse_length
bsf mode,7
call time_counter

addlw 0ffh
bz default_pulses ; if no 9th channel (10th pulse) then use the default settings

movlw D'400'/D'12'
addwf counter,f ; because the counter starts at the end of the pulse
movf counter,w ; 1 counter step means 12 usec
addlw D'256'-ch9_range_min/D'12'
bnc default_pulses ; if the 9th channel is too short then use the default setting

movf counter,w ; 1 counter step means 12 usec
addlw D'256'-ch9_range_max/D'12'
bc default_pulses ; if the 9th channel is too long, then use the default pulse setting

movlw range_check/4 ; settings for reduced power (range check) and failsafe on
movwf first_pulse

goto wait_frame_gap ; if the 9th channel is in the proper range,
; then use the above pulse settings
;
; -------------------------------------------------------------------
; | |
; | Interrupt |
; | |
; -------------------------------------------------------------------
;
; Interrupt starts on positive edge of the irq input, GP2.
; The routine sends out a pulse_length long positive pulse on GP0. One step gives 4 usec.
; If pulse_length = 0 no pulse generated.
; The routine clears the mode.7 bit, it tells to the main program that irq occoured.
;
interrupt:
movf pulse_length,w
addlw 0
bz nopulse

bsf GPIO,0 ; output pulse start
irq1:
nop
nop
nop
nop
nop
decfsz pulse_length
goto irq1

bcf GPIO,0 ; output pulse end
nopulse:
bcf mode,7
bcf INTCON,INTF
retfie

; -------------------------------------------------------------------
; | |
; | Time counter |
; | |
; -------------------------------------------------------------------
;
; It's a 3 ms delay loop, if no input pulse received. In this case it returns with 1.
; If a pulse received, irq starts and clears the mode.7 bit. Then the routine returns with 0.
; In this case the run time is stored in counter, 1 step means 12 usec.

time_counter:
clrf counter
tc1:
btfss mode,7
retlw 0 ; 0 means that it returns because of irq occoured
nop
nop
nop
nop
nop
nop
nop
nop
nop
nop
nop
nop
nop
nop
nop
nop
nop
nop
nop
incfsz counter
goto tc1
retlw 1 ; 1 means it counted up to 3ms

; -------------------------------------------------------------------
; | |
; | delay counter |
; | |
; -------------------------------------------------------------------
;
; It's delay loop. delay = delay_counter * 10 usec.

delay_loop:
goto dl2
dl1:
nop
nop
nop
nop
nop
nop
dl2:
nop
nop
nop
nop
nop
nop
nop
nop
nop
nop
nop
decfsz delay_counter
goto dl1
return




end


The hex code:
:020000040000FA
:020000000828CE
:020008006D2861
:1000100000000000000000008312850107309900F5
:1000200083169F01043085000F1683120B160514EA
:10003000B2170030B4008B108B174830B600B217DF
:10004000B21B2028B60B1F2805106930B500B21767
:100050007D20FF3E031D27283508B400B217B21BD0
:100060002F28E408B400B217B21B34286430B4005F
:10007000B217B21B39286430B400B217B21B3E2845
:100080006430B400B217B21B43286430B400B21716
:10009000B21B48286430B400B217B21B4D2864303C
:1000A000B400B217B21B52286430B400B217B21BAE
:1000B00057280030B400B2177D20FF3E03192528D1
:1000C0002130B3073308623E031C25283308563E0F
:1000D000031825286E30B50027283408003E031980
:1000E0007A28051400000000000000000000B40B96
:1000F00072280510B2138B100900B301B21F00342F
:1001000000000000000000000000000000000000EF
:1001100000000000000000000000000000000000DF
:10012000000000000000B30F7E2801349D2800006D
:1001300000000000000000000000000000000000BF
:1001400000000000000000000000000000000000AF
:06015000B70B9728080020
:02400E00D43F9D
:00000001FF

[pegase]

Hi mmormota,

I'am studying your source code to make something like for my FX18 radio.

Your modul seems to need positive input pulses and generate positive output pulses.

Is it exact ? I suppose it is.

I scope input signal of radio board : 3.3V peak to peak, positive pulses.

So as I only have PPM with negative pulses available I have to change input polarity of firmware. I'll try by patching bin.

Thanks mmormota to give us source and bin. This will be a great help for me.

Pegase

[coro]

Thank You very much for the great idea and sharing the code.
I have EVO9, and also I like Futaba FASST system much more than any other available.
Subscribed and really thank You.
Next step, I have to purchase RF module (is it usable with any Futaba FASST module?) and PIC, or perhaps I will rewrite Your code for some ATTiny mcu.
Merry Christmas!

[cp1]

GCC code for an ATtiny25 is available on www.drivecalc.de. I made it for my son's MPX Cockpit SX. The adapter swaps channels 3 and 4 and adds a 0% signal on channel 8 for failsafe.

Christian

[mmormota]

Another version built with unmodified Evo9 , the external FASST box connected via trainer port. The radio is working with the internal 35MHz synth module too.

The firmware and the shamatics is the same, just the ppm input is limited to 3V using a series 47kOhm and a parallel white Led.

Range check and fail-safe function is working.

[coro]

Thank You very much for writing and sharing GCC source code, it saves a lot of time.
External module using trainer port is excellent idea.

[cp1]

Hi coro,

you're welcome. Are you going to use a Cockpit SX? Otherwise, if there is no need to swap channels, you could use much simpler code. PM me your address, if you want to receive that simpler version.

Christian

[cp1]

I have posted a new software version today, featuring true 16 bit resolution.

[coro]

Dear Christian, no, than You, I have no FASST module yet. I am using and I will be upgrading MPX Royal Evo 9. Not right now..
I have stopped thinking about new transmitter purchase, and I am glad that I found this sollution. I will look into Your code, as well as mmormota code, further, once I get ready.
And thank You for 16-bit version as well.

[cp1]

Hi Coro,

for the Evo 9 you could use the code I have made for my Evo 12. Just PM me if want to receive it.

Christian

[mmormota]

Warning

The additional box version becames ZEROID.
It's possible reason, that sometimes the FASST panel didn't boot up properly (I mean the LED's keep blinking). The owner in order to test it, many times switched on and off the radio. It happened before the ZEROID issue surfaced in this forum.

-------------------------

The built-in pcb works without issues, and boot up properly without a single exception. The same the situation, if the additional box version is switched on with RF tilt (pushing the wrench button...).

The cause of the boot up issue is that the radio communicates first with the internal synth module. It takes some time, and during this time no proper ppm signal is generated for the FASST pcb input. The late start of the ppm signal causes that sometimes that the FASST panel just keeps blinking.

[cp1]

At this time there are 4 external moduls in our club, all driven by my ATtiny code, and we have checked them for the zero ID issue, of course. So far, there is no evidence.

mmormota, how do you identify a zero ID transmitter modul? You cannot read the ID, can you? The only way that I know of is by trying to connect to someone else's RX. If that person also has a zero ID TX, you will be able to take over the control. If you have a zero ID module, how can you be sure it had an ID when you purchased it?

By the way, I still have to see the boot up issue you are talking about. Ever since I am using code that produces accurate timing, the LEDs never kept blinking.

[mmormota]

At this time there are 4 external moduls in our club, all driven by my ATtiny code, and we have checked them for the zero ID issue, of course. So far, there is no evidence.

Most probally the reason was the test, not the modification. During the test, the radio was many times rapidly switched on/off to check if it starts properly. That time the ZGUID problem was not surfaced, so we didn§t know that this is dangerous.

mmormota, how do you identify a zero ID transmitter modul? You cannot read the ID, can you?

A brand new receiver is working with the radio without binding.

[cp1]

Today I have posted another software version for transmitters that do not need channel swapping, like the MPX Evo. It features latency free transmission, since without swapping there is no need to record and replay the signals. Nevertheless it also adds the motor off signal on channel 8 for the failsafe function, and in case the PPM stream carries less than 7 channels, it amends the missing channels on neutral servo positions.

Christian

[Alvaro Silgado]

Hi,

I'm trying to do my own EVO 2.GHz conversion with a FASST TM-7 module. I'm not an expert on electronics, but with the help of cp1 and mmormota (thank you VERY much!), I have my first schema for the adaptation. It seems this module is easier to adapt since the original Futaba radio module socket drives the module input with open collector (I don't know exactly what it means, but mmormota says so :rolleyes: ).

Now, I have a lot of questions:

1. Is this schema correct?
2. Are the values of the resistors correct?
3. Why to lower the voltage from 9v to 6.1v (due to my resistor's values) at the transistor's base? The base is supossed to act as a trigger with ANY value, isn't it?
4. Is this schema still necessary if I use a negative shift on the EVO?

Thank you very much and sorry for too much questions.


Alvaro.

[Alvaro Silgado]

IT WORKED!!!

Everithing is working perfectly, even the failsafe works OK. I haven't tried it outside home, but it is suppossed to work.

Thank you very much for your help (specially, cp1 and mmormota). This solution is simple and functional.

Now, the last question: will the same schema work with more advanced modules, like TM-10 or TM-14?

Cheers,


Alvaro.

[arocholl]

Quick question guys: is the "trainer port" connection version working for more than 5 channels? I'm asking because as far as I know, EVO9 trainer port only controls 5 channels, but I may be wrong...

[cp1]

The trainer port connection works for up to 8 channels, because it uses PPM format. It is not suitable for the M-10 and the M-14.

[mmormota]

The trainer port connection works for up to 8 channels, because it uses PPM format. It is not suitable for the M-10 and the M-14.

The necessary signal for the TM10-15 is a known format? Maybe it can be done using a uC... ;)

[Alvaro Silgado]

Quick question guys: is the "trainer port" connection version working for more than 5 channels? I'm asking because as far as I know, EVO9 trainer port only controls 5 channels, but I may be wrong...
Hola Arocholl :)

Yes, it works perfectly with the 7th channel. Is the simulator cable what only works with 4 channels.

Un saludo,


Alvaro.

[arocholl]

Hola Arocholl :)

Yes, it works perfectly with the 7th channel. Is the simulator cable what only works with 4 channels.

Un saludo,


Alvaro.

Hola Asilgado :D

Thanks for the info. I got info from some other sources that PPM output is ok till the 5th channel, but not beyond, as apparently you couldn't select "trainer" channels beyond 5th. But I never checked that. So it's nice to know that was not the case.

Gracias illo.

Ariel

[Alvaro Silgado]

Confirmed: it also works on the 4000.

Cheers,


Alvaro.

[chewytm]

Hi,

Has anyone done a similar mod with the 9-12 ch versions of the modules. Maybe internal and not thru the trainer port?

chewy

[darkfa8]

I'm following all these Multiplex Spektrum and FASST conversion articles with great interest.

With Multiplex set to debut their 2.4 version of the EVO radios over the next few days at Nuremburg, I'm curious to see whether or not it will be or can be used with FASST or Spektrum or something proprietory.

I've been a FASST user, but am contemplating a new transmitter for heli use.

I guess the course of these threads may change after we see what Multiplex will do. Maybe they'll make conversion modules for the FM transmitters.