[TOC]

----

# Transmitter “HotRC CT-4A”


## Power on
* Press and hold <kbd>ON</kbd>
* Ascending tone series can be heard
* Release <kbd>ON</kbd>

## Power off
* Press and hold <kbd>ON</kbd>
* Decending tone series can be heard
* Release <kbd>ON</kbd>

## Power LED (red)
* Permanently on → Power OK
* Blinking (and repeated beeping) → Low Battery

## Mixed LED (green)
* on: Some setting possibilities are deactivated
* off: Some setting possibilities are activated

## Lock mode (Green LED “MIXED”)
Enable or disable lock mode
* Power off
* Press and hold <kbd>CH4</kbd>
* Power on
* Release all
-> Green LED "MIXED" is toggled (Illuminated = lock enabled)
Some setting possibilities are deactivated in lock mode

## Neutral position trim adjustment (CH1 & CH2)
Lock mode must be deactivated to make this setting.
* Power on
* Press or hold <kbd>ST.TRIM +/-</kbd> for CH1 or <kbd>TH.TRIM +/-</kbd> for CH2
* A short, high-pitched beep indicates adjustment
* A longer, lower beep indicates the center position

## Max stroke adjustment (CH1 & CH2)
* Power off
* Press and hold <kbd>REV</kbd>
* Power on
* <kbd>POWER</kbd> is blinking
* Release <kbd>REV</kbd>
* Press or hold <kbd>ST.TRIM +/-</kbd> CH1 or <kbd>TH.TRIM +/-</kbd> for CH2
* A short, high-pitched beep indicates adjustment
* A longer, lower beep indicates the minimal or maximal setting
* Use the steering wheel to test the current min and max setting
* Press <kbd>REV</kbd> to confirm the setting. (Two longer beeps)

## Reversal of signal (CH1 & CH2)
Lock mode must be deactivated to make this setting.
* Power on
* Press and hold <kbd>REV</kbd> (It beeps continuously)
* Rotate the CH1 wheel or CH2 throttle in the desired direction
* It beeps twice as confirmation
* Release <kbd>REV</kbd>

## Mixed/Hybrid control of CH1 & CH2
Steering with two motors.
* Power off
* Press and hold <kbd>CH3</kbd>
* Power on
* Release all

## Fail save
Lost connection defaults, out of control protection)
* Power off
* Press and hold <kbd>TH.TRIM -</kbd>
* Press <kbd>ON</kbd>
* <kbd>ON</kbd> LED is blinking + beeping (Receiver might show blinkcode for "Out of control protection" setup mode)
* Adjust and hold channels as you want them to be as default
* Press <kbd>TH.TRIM -</kbd> to set the Current channel values as defaults

## Modes for CH3 & CH4
Switch between toggle or up/down mode for CH3 & CH4
* Power off
* Press and hold <kbd>ST.TRIM -</kbd>
* Power on

## Uni-, bidirectional CH2
Switch between unidirectional or bidirectional mode of CH2
* Power off
* Press and hold <kbd>TH.TRIM +</kbd>
* Power on
(Observation: When the receiver is turned on and the throttle is pressed, this mode maybe is automatically set.)

## ?
* Power off
* Press and hold <kbd>ST.TRIM +</kbd>
* <kbd>POWER</kbd> LED is blinking
* ??
* Press <kbd>ST.TRIM -</kbd> to exit

----

# Receiver “HotRC F-04A”


## Green LED
* Slowly blinking → No connection to transmitter
* Fast blinking → not paired
* Continuously lit → Connected to transmitter

## Blue LED “digital” and “analog” mode
* Off → PWM signal with period of 20ms (50Hz). 50% duty cycle is the neutral position. Called "analog mode"

     ┏━━━━━┓     ┏━━━━━┓ 
     ┃     ┃     ┃     ┃
    ━┛     ┗━━━━━┛     ┗━━
     ├─50%─┤
     ├────20ms───┤

* On → Square signal every 3ms (333Hz). (Positive signal length unknown.) Called "digital mode"
* Fast blinking (together with fast blinking green LED) → "Out of control protection" setup mode

## Switch between “digital” and “analog” mode
* Press and hold <kbd>BIND</kbd> for 5 seconds
* Blue LED indicator changes mode
* Release <kbd>BIND</kbd>

## Bind
* Turn transmitter off
* Green LED of receiver flashes slowly
* Press <kbd>BIND</kbd>
* Green LED of receiver flashes fast
* Turn on the transmitter
* Green LED of receiver lit continuously

## Fail save, lost connection function (Out of control protection)
See instruction for transmitter

https://www.youtube.com/watch?v=AY9xh2v6Wjs