Tx2 - v2.0.3 Instructions


Tx2 is a reprogrammed receiver which is used to make a 2.4GHz transmitter compatible with other DSM2 receivers.
It has 6 'profiles' to help you find the most suitable for your needs.

EXAMPLE:
Tx21, Tx22 and Tx23 are controllers for trains using Profile 1 and Profile 3 of Tx2.
Controls for Speed, Direction, Inertia, Lights.
EXAMPLE:
Coax heli and cheap plane transmitters
Proportional or switched control of up to 7 channels


PRODUCT: Tx2

GENERAL INFORMATION:


Converted receiver
(3.1v is source for Vref)

Supply power to any of the 3.2-10v pins
(1-2S lipo or 3-6 AA or 9v PP3)

PIN FUNCTIONS:
(* = Default profile)



Control Pin
PROFILE 1*
Trains
(Tx22)

PROFILE 2
Conventional
(5ch)
PROFILE 3
Trains
(Tx23)
PROFILE 4
Conventional
(7ch)
PROFILE 5
Trains
(Tx20)

PROFILE 6
Trains
(Tx21)

Pin1 Ch1 analogue Ch1 analogue Ch1 analogue Ch1 analogue Ch1 analogue Ch1 analogue
Pin2 Ch2 analogue Ch2 analogue Ch2 analogue Ch2 analogue Ch2 digital (mid/low) Ch2 digital (mid/low)
Pin3 Ch3 analogue Ch3 analogue Ch3 analogue Ch3 analogue Ch3 analogue Ch3 analogue
Pin4 Ch4 digital (mid/low) Ch4 analogue Inertia analogue Ch4 analogue Ch4 digital (mid/low) Ch4 digital (mid/low)
Pin5 Ch5 digital + BIND Ch5 digital + BIND Ch5 analogue + BIND Ch5 analogue + BIND/REVERSE Ch5 digital (high/low) + BIND Ch5 digital (high/low) + BIND
Pin6 Inertia analogue REVERSE Ch6 analogue Ch6 analogue Ch6 digital (high/low) Inertia analogue
Pin7 TRIM TRIM Ch7 analogue + TRIM Ch7 analogue + TRIM TRIM TRIM
LED on PCB LED1 output LED1 output LED1 output LED1 output LED1 output LED1 output
Pin8 LED2 output + PROFILE LED2 output + PROFILE LED2 output + PROFILE LED2 output + PROFILE LED2 output + PROFILE LED2 output + PROFILE

ANALOGUE INPUTS:
Tx2 is designed to have joysticks and potentiometers connected to create proportional channel movements.
The proportional movements come from the division of a reference voltage by each pot.
Inputs that are capable of this are called 'analogue' (= infinitely adjustable).
Channel positions will be random if analogue pins are left unconnected (they 'float').

REFERENCE VOLTAGE:
Tx2 has a 3.1v reference voltage (Vref) but the analogue inputs can only measure up to 2.1v.
It is easy to create a 50% voltage with 2 equal resistors so this is necessary to create a 1.55v reference.
For example, a 10k pot creates a proportional 0-1.55v range when in series with a 10k resistor.
The pot and resistor can be any equal value between 4k7 and 100k but 10k for both is a common choice (10k = 10 000 ohms).


DIGITAL INPUTS:
Some inputs are classed as 'digital' which means they can only have two states, High (3.1v) or Low (0v).
When nothing is connected to digital inputs, their internal resistors pull them up to 3.1v.
A switch or bind plug is used to pull them Low (0v).

THROWS:
Tx2 uses 10bit resolution (1024 steps max).
150% throws: 0-1.55v = 0-1023 = 0.9-2.1ms servo pulse.
100% throws: 0-1.55v = 171-852 = 1.1-1.9ms servo pulse.

THROW OPTIONS:
1: Pin1 (motor) 100% and Pins2-7 150% (default).
2: Pins1-7 150%.
3: Pins1-7 100%.

LED:
If Tx2 is built into a box, Pin8 can drive an external 'LED2'.

MAXIMUM VOLTAGES:
PIN 1-8 Analogue input: 0-1.55v.
PIN 1-8 Digital input: 0v or 3.1v.
PIN 1-8 Max input: 3.6v.
Battery: 3.2-10v.
Low voltage protection: None.



BIND:
Receivers have to be bound to Tx2 for them to accept its signals:
1. Get the receiver into bind mode (led flashing fast).
2. Press and hold the BIND button, switch Tx2 on and then release the BIND button.
3. The Led will flash slowly for a few seconds.

TRIMS:
Trims change in steps of 4 and can shift the entire range without restriction.
One button is used to change trims of any channel:
1. Move joystick/pot/switch to 'center' position (0.8v).
2. Press and hold TRIM button and the Led will go off.
3. Move joystick/pot/switch 'full throw' in direction required for trim change (0v or 1.55v).
4. Led will flash and Trim will change '1 click' per half second.
5. Trims have 128 'clicks' each way and the Led will stay on for 2 seconds when the trim value returns to center.
6. Release TRIM button to save.

Separate trim pots can also be used with each channel. See 'trim pot' section below.

REVERSE:
One button is used to reverse any channel:
1. Move joystick/pot/switch to 'center' position (0.8v).
2. Press and hold REVERSE button and the Led will go off.
3. Move joystick/pot/switch to 'full UP' (1.55v) and the channel will change to NORMAL direction immediately.
4. Move joystick/pot/switch to 'full DOWN' (0v) and the channel will change to REVERSE direction immediately.
5. Release REVERSE button to save.

PROFILE:
Pin8 is used to change the Profile.
You will normally set this before doing anything else and never change it again.
1. Make sure Pin5 has nothing connected (Pin5 floating or at 3.1v).
2. Connect Pin8 to 3.1v (Pin8 = 3.1v).
3. Apply power to Tx2.
4. LED1 will flash the current Profile twice
5. While Pin8 continues to be 3.1v, the LED will scroll through the options.
6. Release Pin8 to save.
7. Switch Tx2 off when the led stays on.

THROWS:
Pins 5 and 8 are used to change Throw options.
1. Place the Bind plug on Pin5 or press Bind button (Pin5 = 0v).
2. Connect Pin8 to 3.1v (Pin8 = 3.1v).
3. Apply power to Tx2.
4. LED1 will flash the current Throws option twice
5. While Pin5 continues to be 0v, the LED will scroll through the options.
6. Release Pin5 to save (Pin5 floating).
7. Switch Tx2 off when the led stays on.




TRAIN FEATURES:

'MOTOR' CHANNEL:
The motor channel controls speed and uses different channel numbers to control up to 7 trains individually.
It will normally be 'center off' if the Direction feature is not used.

'DIRECTION' CHANNEL:
The direction channel will only have any effect with ESC's that require a second channel to set Fwd/Rev direction.
On Tx21 and Tx22 the Direction switch is often used for directional lights.

INERTIA / BRAKE / MOMENTUM:
The inertia control modifies the Motor channel to smooth out changes in speed.
It ranges from having no effect to making the speed ramp up/down progressively over up to 60 seconds.
The Led flickers while a transition is in progress and reducing the inertia setting while in motion has a braking effect.

LIGHTS:
The Direction channel can be used to switch up to 4 lights on and off with DT receivers.
The Bind button can be used to switch up to 2 lights on and off DT receivers.

LOCO SELECTION:
Rx6x receivers have a 'Selecta' feature which allows locos to be brought in and out of service without touching them.
Tc22 has a 12-way switch to allow up to 12 locos to be controlled at the same time.

COUPLING:
Several channels can be used to control a servo to operate a coupling.



PROFILE 1:

Profile 1 is intended for trains.

Note: The TRIM, REVERSE and PROFILE CHANGE features will not normally be used.


Control Pin

Function
Pin1 Ch1 analogue (Motor)
Pin2 Ch2 analogue
Pin3 Ch3 analogue (Direction)
Pin4 Ch4 digital (mid/low)
Pin5 BIND + Ch5 digital
Pin6 Inertia analogue
Pin7 TRIM + CAL1
LED on PCB LED1 output
Pin8 LED2 output + PROFILE

WIRING DIAGRAM:
1 train controller with switches for Direction and Ch2
1 train controller with switch for Direction (Tx21)
1 train controller with pot for Direction

PIN 1:
Pin1 is expected to control motor speed using Channel 1.
Changes are smoothed by the Inertia feature.

PIN 2:
Pin2 is used to control the Selecta feature in Tx22 using Channel 2.
Alternatively, Ch2 is a spare channel for any purpose.

PIN 3:
Pin3 is expected to control 'motor direction' using Channel 3 on receivers/ESCs that use a separate Direction channel.
Alternatively, Ch3 is a spare channel which is often used for lights with Tx22.

PIN 4:
Pin4 is digital and has an internal pullup and is used to control Channel 4.
It is at its mid position when high (button released) or low position (button pressed).

PIN 5:
Pin5 is digital and has an internal pullup.
It requires a pushbutton switch or bind plug to pull down to 0v.
The Transmitter will enter Bind mode if the Bind button is being pressed when Tx2 is switched on.
The Bind button can be used to toggle Ch5 in normal use for lights, servo etc.
It is also used to calibrate Ch1 and Ch2 (see below).

PIN 6:
Pin6 controls Inertia.
It modifies the Ch1 position and is not used for Ch6.

PIN 7:
Pin7 is digital and has an internal pullup.
A bind plug is normally used to pull down to 0v (=active) to set TRIM.


PIN 1 AND PIN 2 CALIBRATION:
Tx22 has a pot that has a 'click' at the center position. When Throttle is used 'center off' it needs to center accurately so that the 'click' on the Tx matches the 'off' position in the receiver. Tx22 uses Ch2 for a 12-way Selecta switch. This can also be calibrated so it uses the same position on all units. Calibration is done using the Bind button while Tx22 is on. After ~20s Ch1 is calibrated and after ~25s Ch2 is calibrated.
1. Center the Motor pot. On Tx22 put the 12-way Selecta switch in the 6th position (starting from full CCW/0v).
2. Press and hold the Bind button for ~20s until the led goes off. Ch1 should now be calibrated.
3. Release the Bind button if only Ch1 needs calibrating. Continue holding to calibrate Ch2.
4. The led will come on for 3s then go off again. Ch2 should now be calibrated. Release the Bind button.
Calibration uses the TRIM feature. So the effect it has can be adjusted by following the TRIM instructions.



PROFILE 2:

Profile 2 is a simple 5 channel transmitter.

Profile 2 is identical to Profile 1 except:
1. Pin4 is transmitted as Channel 4.
2. There is no Inertia function.


Control Pin

Function
Pin1 Ch1 analogue
Pin2 Ch2 analogue
Pin3 Ch3 analogue
Pin4 Ch4 analogue
Pin5 BIND + Ch5 digital  
Pin6 REVERSE
Pin7 TRIM
LED on PCB LED1 output
Pin8 LED2 output + PROFILE

WIRING DIAGRAM:
5 channels

PINS 1-4:
Pins 1-4 are analogue and require pots to control their values.

PIN 5:
Pin5 is digital and has an internal pullup.
It requires a pushbutton switch or bind plug to pull down to 0v (=active).
It controls BIND on startup and Ch5 in normal use.
Ch5 can only be at one extreme (position 0) or the other (position 1023).
Ch5 cannot be reversed or trimmed.

PIN 6:
Pin6 is digital and has an internal pullup.
It requires a pushbutton switch or bind plug to pull down to 0v (=active).
It controls channel REVERSE.

PIN 7:
Pin7 is digital and has an internal pullup.
It requires a pushbutton switch or bind plug to pull down to 0v (=active).
It controls TRIM.



PROFILE 3:

Profile 3 is intended for trains.

Note:
1. If you don't need to control 3 trains, you can use spare inputs to control other things.
2. The TRIM feature will normally only be used if the motor control knob needs 'centering' more accurately.
3. The PROFILE change switch will not normally be needed.
4. There is no channel REVERSE feature.


Control Pin

Function
Pin1 Ch1 analogue (Motor1)
Pin2 Ch2 analogue (Motor2)
Pin3 Ch3 analogue (Direction1)
Pin4 Inertia analogue
Pin5 Ch5 analogue (Direction2) + BIND
Pin6 Ch6 analogue (Motor3)
Pin7 Ch7 analogue (Direction3) + TRIM
LED on PCB LED1 output
Pin8 LED2 output + PROFILE

WIRING DIAGRAM:
3 train controller

'MOTOR' CHANNELS:
Pins 1, 2 and 6 are used with pots to control motor speed with Channels 1, 2 and 6.
When used with conventional ESCs (forward/reverse on one channel), center is usually off.
When used with ESCs that have a separate Direction channel, full rotation controls the full power range.
Pins 1, 2 and 6 are all set to 100% with Throws Option 1.

'DIRECTION' CHANNELS:
Pins 3, 5 and 7 are used with switches to control motor direction with Channels 3, 5, and 7.
These pins are only effective with receivers/ESCs that use a separate channel for Direction.
Alternatively, they can be used to control up to 4 lights each with DT receivers (eg: center off switches as per Tx23).

PIN 4:
Pin4 controls Inertia.
Pin4 modifies the Ch1, 2 and 6 positions and is not used for Ch4.
Ch4 can be changed with the Bind button to switch up to 2 lights on and off with DT receivers (see below).

PIN 5:
Pin5 requires two switches:
1. A toggle switch selects Direction2 using Channel 5 (between 0.13v and 1.42v).
2. A pushbutton (or 'Bind' plug) pulls Pin5 down to 0v to set BIND.
The Transmitter will enter Bind mode if the Bind button is being pressed when Tx2 is switched on.

The Bind button can also be used to control Ch4 in normal use:
When the Bind button is pressed, Ch4 is transmitted at its low position (0 / 0.9ms).
When the Bind button is released, Ch4 is transmitted at its mid position (511 / 1.5ms).

PIN 7:
Pin7 requires two switches:
1. A toggle switch selects Direction3 using Channel 7 (between 0.13v and 1.42v).
2. A pushbutton (or 'Bind' plug) pulls Pin7 down to 0v to set TRIM.



PROFILE 4:

Profile 4 is a 7 channel transmitter.


Control Pin

Function
Pin1 Ch1 analogue
Pin2 Ch2 analogue
Pin3 Ch3 analogue
Pin4 Ch4 analogue
Pin5 Ch5 analogue + BIND/REVERSE
Pin6 Ch6 analogue
Pin7 Ch7 analogue + TRIM
LED on PCB LED1 output
Pin8 LED2 output + PROFILE

WIRING DIAGRAMS:
7ch: 7 pots
7ch: 1 motor pot and 6 switched channels

PINS 1-4 and 6:
Pins 1-4 and 6 are analogue and require pots to control their values.

PIN 5:
Pin5 requires a pot and pushbutton for BIND/REVERSE:
1. The pot controls channel 5.
2. The pushbutton pulls Pin5 down to 0v to set BIND on startup and REVERSE in normal use.

PIN 7:
Pin7 requires a pot and pushbutton if trim is required:
1. The pot controls channel 7.
2. One pushbutton pulls Pin7 down to 0v to set TRIM.



PROFILE 5:

Profile 5 is intended for trains (Tx20).

Note: The TRIM and PROFILE CHANGE features will not normally be used.


Control Pin

Function
Pin1 Ch1 analogue (Motor)
Pin2 Ch2 digital (mid/low)
Pin3 Ch3 analogue (Direction)
Pin4 Ch4 digital (mid/low)
Pin5 Ch5 digital (high/low) + Bind
Pin6 Ch6 digital (high/low)
Pin7 TRIM
LED on PCB LED1 output
Pin8 LED2 output + PROFILE

WIRING DIAGRAM:
Tx20 circuit

PIN 1:
Pin1 is expected to control motor speed using Channel 1.

PIN 2:
Pin2 is digital and has an internal pullup and is used to control Channel 2.
It is at its mid position when high (button released) or low position (button pressed).

PIN 3:
Pin3 is expected to control 'motor direction' using Channel 3 on receivers/ESCs that use a separate Direction channel.
Alternatively, Ch3 is a spare channel which is often used for lights with Tx21/Tx22.

PIN 4:
Pin4 is digital and has an internal pullup and is used to control Channel 4.
It is at its mid position when high (button released) or low position (button pressed).

PIN 5:
Pin5 is digital and has an internal pullup.
It requires a pushbutton switch or bind plug to pull down to 0v.
The Transmitter will enter Bind mode if the Bind button is being pressed when Tx2 is switched on.
The Bind button can be used to toggle Ch5 in normal use for lights, servo etc.
It is also used to calibrate Ch1 (see below).

PIN 6:
Pin6 is digital and has an internal pullup and is used to control Channel 6.
It is at its high position (button released) or low position (button pressed).

PIN 7:
Pin7 is digital and has an internal pullup.
A bind plug is normally used to pull down to 0v (=active) to set TRIM.


PIN 1 CALIBRATION:
Tx20 has a pot that has a 'click' at the center position. When Throttle is used 'center off' it needs to center accurately so that the 'click' on the Tx matches the 'off' position in the receiver. Calibration is done using the Bind button while Tx20 is on. After ~20s Ch1 is calibrated.
1. Center the Motor pot.
2. Press and hold the Bind button for ~20s until the led goes off. Ch1 should now be calibrated.
3. Release the Bind button.
Calibration uses the TRIM feature. So the effect it has can be adjusted by following the TRIM instructions.



PROFILE 6:

Profile 6 is intended for Tx21 (trains).

Note: The TRIM and PROFILE CHANGE features will not normally be used.


Control Pin

Function
Pin1 Ch1 analogue (Motor)
Pin2 Ch2 digital (mid/low)
Pin3 Ch3 analogue (Direction)
Pin4 Ch4 digital (mid/low)
Pin5 Ch5 digital (high/low) + Bind
Pin6 Inertia analogue
Pin7 TRIM
LED on PCB LED1 output
Pin8 LED2 output + PROFILE

WIRING DIAGRAM:
Tx21 circuit

PIN 1:
Pin1 is expected to control motor speed using Channel 1.

PIN 2:
Pin2 is digital and has an internal pullup and is used to control Channel 2.
It is at its mid position when high (button released) or low position (button pressed).
Pin2 is not used on Tx21 and can be left unconnected.

PIN 3:
Pin3 is expected to control 'motor direction' using Channel 3 on receivers/ESCs that use a separate Direction channel.
Alternatively, Ch3 is a spare channel which is often used for lights with Tx21/Tx22.
Pin3 is pulled high or low with a 2-position switch on Tx21.

PIN 4:
Pin4 is digital and has an internal pullup and is used to control Channel 4.
It is at its mid position when high (button released) or low position (button pressed).
Pin4 is not used on Tx21 and can be left unconnected.

PIN 5:
Pin5 is digital and has an internal pullup.
It requires a pushbutton switch or bind plug to pull down to 0v.
The Transmitter will enter Bind mode if the Bind button is being pressed when Tx2 is switched on.
The Bind button can be used to toggle Ch5 in normal use for lights, servo etc.
It is also used to calibrate Ch1 (see below).

PIN 6:
Pin6 controls Inertia.
It modifies the Ch1 position and is not used for Ch6.
Ch6 is fixed at its mid position and cannot be changed.

PIN 7:
Pin7 is digital and has an internal pullup.
A bind plug is normally used to pull down to 0v (=active) to set TRIM.
Ch7 is fixed at its mid position and cannot be changed.


PIN 1 CALIBRATION:
Tx21 has a pot that has a 'click' at the center position. When Throttle is used 'center off' it needs to center accurately so that the 'click' on the Tx matches the 'off' position in the receiver. Calibration is done using the Bind button while Tx21 is on. After ~20s Ch1 is calibrated.
1. Center the Motor pot.
2. Press and hold the Bind button for ~20s until the led goes off. Ch1 should now be calibrated.
3. Release the Bind button.
Calibration uses the TRIM feature. So the effect it has can be adjusted by following the TRIM instructions.



SWITCHES

A 3-position switch is a common requirement:

Rx60 and Rx61 have a feature called Selecta which requires a multi-position switch. The wiring diagrams and resistor values in the tables below describe how to set Tx2 up for these. The default throws are 150% but use the values for 100% when that option is enabled. Any analogue channel can be used except those intended for motor control in trains (these are affected by the Inertia feature). The Selecta switch never connects the Tx2 input to 0v or 1.55v. So inputs can also be used for things like Binding which connect the input to 0v to be effective.


12-way

3-way

6-way

12-way

150%

100%


TRIM POT

A separate pot can be placed in parallel with a joystick pot to create a more easily adjustable 'mechanical' trim for each channel. Two examples in the link below.




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