Micron Receiver Features

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Radio | Speed Controller (ESC) | Servo Output | Input/Output | General Configuration | Programming

Micron receivers implement a set of features for model rail locomotives and land-based vehicles. The majority of features are common to all receivers, but some will be specific - refer to a receiver's user manual and programming table for details:

• MR001: micronrc.co.uk/mr001, micronrc.co.uk/mr001-progtable
• MR601: micronrc.co.uk/mr601 micronrc.co.uk/mr601-progtable
• MR603: micronrc.co.uk/mr603 micronrc.co.uk/mr603-progtable

Each receiver is configured with a default set of features which is described on the receiver's web page and in the user manual for the receiver. Most receivers contain 4 pre-set configurations which can be selected using a power-on jumper or by programming the receiver (see the user manual for details). Different configurations are always available to special order - contact us.

The radio part of the receiver is responsible for connecting with a transmitter and decoding the control data. Some receivers have a separate RF module with its own LED to indicate signal quality, others integrate the RF and receiver behaviour into one chip with a common status LED. Almost all Micron model rail and land vehicle components use the Spektrum DSM2/DSMX protocols which gives access to a wide variety of 3rd party products. it also means that a Micron receiver can be used with any real Spektrum or third party transmitter that implements the Spektrum protocols. This includes all Micron model rail transmitters.

DSM2/DSMX uses a spread-spectrum type radio protocol where the contol information is 'encrypted' using the transmitter ID. Thus, only a receiver which has stored a transmitter's ID is able to decode the control data. That is how many R/C systems can be used within a small space without interferring with each other.

The association of Tx control to R/C channel and channel values for Micron model rail transmitters is described in the user manual for each transmitter. All of them provide these common mappings:

ch1:	throttle/regulator fwd/rev: full reverse=chan low, stop=chan mid, full forward=chan high low-off: stop=chan low, full throttle=chan high
ch2:	Selecta (if implemented on that transmitter) #1=chan low, #6=chan mid, #12=chan high
ch3:	toggle switch for direction (if low-off throttle) or auxiliary functions, also used for Rx programming reverse/down=chan low, forward/up=chan high
ch5:	bind button pressed=chan low, not pressed=chan high

Micron receivers have a variety of outputs, each type is denoted by a letter (H, F, P, etc):

• H: one or more fwd/rev motor speed controllers
• F: switch (usually 2A capable), used as an on/off switch to control an external device (e.g. high current LED, smoke generator, ...) or with PWM as a single direction motor speed controller or light dimmer
• P: low current logic level, usually 0V when off and 3.3V when on; used to control low-current LEDs or can output a servo signal

Receivers are provided with a set of predefined R/C channel to output mappings - the configuration. Most receivers have 4 selectable configurations for common usage.

A transmitter can be bound with any number of receivers, so long as they use compatible protocols, but a receiver can normally be bound to only one transmitter. All receivers will respond to the transmitter, so only one receiver should normally be switched on at any time. An exception to this is for receivers and transmitters that support the Selecta feature (all Micron receivers support Selecta and some of the Micron transmitters also support Selecta).

The general process for binding is:

1. receiver is placed into bind mode - usually indicated by a rapid LED flash
2. the transmitter is then switched on in bind mode - the method for doing this varies, refer to the transmitter manual

Most Micron receivers support manual and auto binding:

Selecta enabled transmitters have a 12-way rotary switch for controlling the value (i.e. code) sent on the Selecta channel. A receiver's Selecta code is store during bind. Simply rebind if you need to change Selecta switch position for a model.

Micron receivers have at least one integrated bi-directional ESC (Electronic Speed Controller) for brushed motors. Some receivers also support the connection of an external ESC for either brushed or brushless motors - this is done by configuring an output as a SERVO-ESC.

The default direction control behaviour is latching - i.e. the centre position is not a neutral gear. This is essential when using a joystick type transmitter where the control is self-centring. The mode may be changed by programming to implement a neutral gear where the throttle/speed control has no effect when the direction control is centred.

ESC Behaviour

For both options, the direction control affects the ESC direction only when the ESC is stopped. If the loco is moving, an intent to change is saved and implemented when the loco has stopped.

latching:

Allows use of a 3-way self-centred toggle switch or a self-centred stick on a model aircraft type transmitter. ESC direction is changed by pushing the control in the forward or reverse direction and releasing.

stop when neutral:

For use with a latching 3-way toggle switch. The ESC, or regulator servo, output is disabled when the 3-way toggle switch is in the centre.

Servo Behaviour

follows control:

The servo immediately follows the direction control movement. This is the default and useful for variable reversing gear which can be adjusted while the loco is in motion.

change when stopped:

The servo moves only when the throttle/regulator control is at stop. This should be selected when the reversing gear must be not moved unless the loco is stopped.

THIS IS A SAFETY FEATURE AND DISABLING IS DISCOURAGED.

Any P output can be configured as a servo with the normal 1ms-2ms pulse width signal repeated every 20ms. For rotary or stick-type transmitter controls, the position of the servo arm is proportional to the position of the controlling channel. Transmitter push buttons and toggle switches may also be used to control a servo output, in this case the servo arm moves immediately to the low, mid or high position as specified in the transmitter user manual.

Many Micron receivers have a 3.3V output which can be used to power a small servo. The maxium current is usually limited to no more than 200mA - see the receiver user manual for the specific max current.

A typical use is to drive 2 external ESC mixing throttle and steering R/C channels for differential steering on a boat or tracked vehicle. For example: MR001d with ESC on P1 and P2, throttle on R/C ch1 and steering on R/C ch2:

2-1-1-1-1           external ESC on p1 using R/C ch1
2-1-4-2-1           external ESC on p2 differential with P1
2-1-5-2-2           50% mix with R/C ch2

Another use is to drive an external switch unit to control a sound unit. For example, a MR001d with Mtroniks microSwitcher on P4 controlling a digiSound horn and engine start/stop from a Tx20v2 using F1 and F2:

2-4-1-4-1           switcher connected to P4 controlled by R/C ch4 (Tx20 F1)
2-4-4-8-1           P8 as 2nd output (this is not used)
2-4-5-2-4           100% mix with R/C ch2 (Tx20 F1)

One servo output may be adjusted at a time. The output is first selected by programming and then the transmitter control is used to increase or decrease the servo throw:

• R/C channel 3 (toggle switch on most Micron transmitters, elevator on stick type transmitters) is used for most outputs
• R/C channel 1 (throttle) is used when adjusting a servo on R/C channel 3

• within 5 seconds, move the control for the output being adjusted to the end that needs adjustment
• increase or decrease the servo end-point:
  • on Micron or stick type transmitters, use the throttle control if a servo on R/C channel 3 is being adjusted:
    • hold throttle knob fully CCW or throttle stick at low throttle to decrease travel
    • hold throttle knob fully CW or throttle stick at high throttle to increase travel
  • use the direction toggle, reverser control or elevator stick for servos on all other R/C channels:
    • hold toggle down, reverser to REV or elevator stick down to decrease travel
    • hold toggle up, reverser to FWD or elevator stick up to increase travel
    The receiver LED will flash twice per second as the servo travel is being adjusted and stop flashing when the limit is reached. Take care: the servo may reach its mechanical stop before the increase side adjustment limit is reached.
  • move the servo control to the opposite side if you also need to adjust that end-point
  • centre both controls to finish the adjustment, the receiver will return to normal operating mode after the control corresponding to the P port being adjusted has been centred for 5 seconds.

Go through the above steps to adjust a different servo output pin.

The standard servo range for 100% is 1.1ms to 1.9ms and 0.9ms to 2.1ms for the full 150%. Sometimes this is not enough, e.g. to control bespoke electronics or for a servo with extended travel (the Emax ES9052D can handle a pulse width range of 0.6ms to 2.4ms). This feature allows the servo pulse width range to be increased by up to 200% (3 x the base range or 0.3ms to 2.7ms for a 100% R/C data input).

Note: increasing the output pulse width range beyond +50% should be used with care if a servo is connected - make sure that your servo and control linkages can handle the increased range. If you are not sure, it is recommend to increase the range incrementally.

Receivers have a number of general purpose input and outputs (GPIO) ports, mostly used for output. There are 2 types:

• P - these are logic level outputs that can supply a low current (typically 20mA max), 0V when off and 3.3V when on. They can be used to power LEDs via a series resistor suitable for the desired LED current and for driving servos where the P pad provides the control signal to the white or yellow wire of the servo lead. Some receivers are able to provide 3.3V to micro servos, larger servos must be powered from a separate source - e.g. a 5V regulator connected to the battery. P pads can also be used for input - e.g. shuttle control, remote sensors; see the receiver user manual for information.
• F - these are switches and can control up to 2A; they are open when off and connected to negative when on. For programming, F switches are given numbers sequentially after all P outputs, e.g. if a receiver has 6 x P and 4 x F, the F outputs are numbered 7 to 10. For compatibility with Deltang receivers, F outputs are also labeled with letters, e.g. F1 is A, F2 is B, etc.

• prog 3,4,1,5,1 = P4, normally off, on when Ch5 is low
• prog 3,6,1,3,6 = P6, normally on, off when Ch3 is high

1 R/C channel can be used to control 1 to 4 outputs, the switching action is based on the time that the control is activated low or high: up to 1 second or 2 seconds and greater. The options are:

• <1s momentary: the output is switched on immediately and kept on as long as the control is active - up to 2s when it will switch off
• <1s toggle: the output is toggled if the control is activated for less than 1s
• >2s momentary: the output is switched on if the control is activated for greater than 2s and kept on as long as the control is active
• >2s toggle: the output is toggled if the control is activated for greater than 2s

Front and rear lights are switched based on motor direction. Both start off and either the front or rear light is switched on when the throttle is opened for the first time and stays on when the loco/vehicle stops, changing when the motor direction is changed.

The brake light comes on briefly when the motor stops. The on duration defaults to 1 second and can be set using one of the General Configuration program options.

The reverse light is similar to the rear light and is on when the motor is moving in reverse. It goes off when the vehicle stops.

All auto-light action can be disabled and enabled using a transmitter control by programming the receiver. This feature is off by default and can be configured by programming the receiver.

A short low or high pulse (<1s) on the indicator activation channel will start the indicator flashing on that side: low=left, high=right. A long low pulse (>2s) will start both indicators flashing to simulate hazard lights; another long low pulse will stop the flashing. Hazard flashers are not cancelled by changes on the steering channel.

The flasher can be switched on and off by a low or high pulse on the activation channel.

Automation functions are enabled as soon as they are programmed and may optional be disabled or enabled again using a transmitter control.

The available automation features are:

Buffer Stop:

This allows a loco to be stopped automatically to avoid hitting a buffer or other obstacle. When triggered, the train will decelerate to a stop over a configurable 1 to 6 seconds. The throttle must be closed before the loco can be moved again. The trigger input is deactivated for a period so that the loco can be reversed out of the dead-end and over the trigger magnet (or IR LED) without causing the loco to stop again. This reactivation delay can be set between 10 and 60 seconds in 10 second increments.

Example using P5:

1. Enable Buff Stop by entering the program sequence 6,5,1,3,2 = Menu6, P5, 3 seconds deceleration time, 20 seconds delay before reactivation of trigger
2. Wire a reed switch between P5 and nagative
3. Place a magnet between the tracks 2 seconds travel from where you want the loco to stop (some experimentation may be needed)

Stop & Reverse:

Similar to Buffer Stop except that the loco reverses direction after the pause time. The same throttle setting is used for the reverse motion and changing the transmitter throttle control has mostly no effect once the first stop has been triggered. If the transmitter throttle is closed, the automation is cancelled and the loco can be moved manually until the stop is again triggered. The pause time spent stationary is adjustable for a fixed delay between 10 and 60 seconds plus a set of random delay ranges (4-8s, 8-15s, etc.)

After the pause, the loco will accelerate in the opposite direction and over the same time period specified for stopping. The trigger input is reactivated 10 seconds after the loco has started moving again.

Stop & Continue / Station Stop:

This function provides a station stop feature. The loco continues in the same direction after the pause time.

A typical e-switch configuration comprises a magnetically operated reed switch and a P channel FET to switch the power. P-FETs require a 0V input to switch on so are usually paired with a N channel FET so that a > 2V input will switch the P-FET on - i.e. 3.3V from the POWER output will keep the P-FET on. The reed switch is connected, via isolation diodes, to the P-FET gate and to the receiver SENSE input - thus activation of the reed switches the power on and also signals to the receiver that the reed is activated. The receiver behaviour is to light its LED (and LED2 if connected) when it is powered on and then flash the LED when initialisation has been completed and the POWER output is enabled. The magnet may then be removed from reed. See example e-switch.

The reed is activated again to switch the receiver off. Activating the reed results in the LED (and LED2) flashing slowly for 3s and then rapidly for a further 3s. Removing the magnet while the LED is flashing rapidly will result in the POWER output going to 0V. Keeping the reed activated until the end of the 3s rapid flash will abort the switch off.

An R/C channel may optionally be used for switching off. If this channel is activated for >3s, POWER is turned off.

This section comprises a collection of functions that apply to the receiver as a whole.

LED2 mode options:

• disabled
• normal (as described above)
• as above including when deselected
• always

The LVC trigger point is set automatically based on the battery voltage measured on start-up.

• 3V for < 6V at start-up
• 6V for 6V to 9V
• 9V for 9V to 12V
• 12V for 12V and above

Receivers also have an 'L' input which is used when an external booster module is used to raise a low voltage battery to a higher voltage (e.g. single LiPo cell to 12V). The 'L' input takes priority over the main positive pad.

Although the receiver draws a low current in sleep mode, this is not a substitute for an on/off switch.

Sleep mode can also be configured to be activated after the LVC has triggered. When enabled, the receiver goes into sleep mode 5 minutes after LVC to avoid further draining the battery.

The default configuration for all receivers has cruise control enabled 'cruise control' and allows the loco to keep running if the transmitter is switched off. The cruise control / failsafe mode can be set either using a power-on change or by programming.

The default action when deselected is for the motor to continue running at the last setting; this is appropriate for a continuous loop type layout. This behaviour can be changed to stop when deselected by programming the receiver.

Receiver behaviour can be changed using the transmitter to which the receiver is bound. The receiver must first be put into programming mode and then the direction toggle switch, or reverser knob on Tx24v2, or elevator on a stick type transmitter, is used to enter a program sequence one digit at a time. The receiver LED (and LED2 if enabled) flashes to indicate the value of the current step in the programming sequence. For example, if the current value is 4, the CPU LED flashes 4 times, pauses and repeats - this is called a 4-flash. Where it is possible for the current value to be zero (e.g. low voltage cut-off tenths), this is shown as a single brief flash much shorter than the normal value flash.

The receiver feature set and, hence, the programming table is large. It is presented in a separate document for each receiver which lists all functions that may be changed by programming. The table is split into 5 blocks of related functions each with the same value in the first column.

The table columns contain the program values which must be entered to change a particular function. For example, to change the throttle behaviour from centre-off (forward and reverse on one control) to low-off (separate throttle/regulator and direction/reverser controls) the program sequence 1, 1, 2, 1, 3 is entered. Each digit of this program sequence is taken from the columns, left to right:

One function can be changed at a time. The general method is:

• set receiver into programming mode
• enter a program sequence
• repeat until all programming changes have been made

1. hold the transmitter channel 2 and channel 4 controls at high or low extremes and then switch the receiver on; these are the F1 and F2 buttons on a Tx20v2 and the Selecta switch and S2 button on a Tx22X; the receiver LED will flash rapidly shortly after switch on, centre one or both channel 2 & 4 controls (e.g. release the buttons on Tx20v2 or the S2 button on Tx22X)


2. switch the transmitter and receiver on (they must be bound), wait 5 seconds without touching any controls and then tap out morse SOS (... --- ...) on the transmitter bind button (or toggle the gear switch high to low for a stick transmitter);
   • dots (…) will be a quick press of the button and must be less than 1 second in duration
   • dashes (---) must be greater than 1 second and shorter than 5 seconds – 2 seconds is a reliable time
   • the time between each dot or dash must be less than 5 seconds

When programming mode has been successfully entered, the receiver LED will show a 1-flash - this is the 1 from the first column of the programming table. If you do not get the 1-flash, repeat the procedure to enter programming mode. It usually takes a couple of attempts to get the SOS method correct if you have never done it before.

Enter a Program Sequence

One programming change requires up to five choices to be made. These are called 'levels' and each has several options. They are documented in the programming table. Completion of a programming change exits programming mode and requires the receiver to be placed into programming mode again for the next change.

It is a good idea to write the programming sequence on a piece of scrap paper and cross off each digit as it is entered so that you don't lose track of where you are in the sequence. You always start at the top of the first column and 1-flash is displayed on entering programming mode.

• The flash count for a level is incremented by setting the R/C channel 3 control low and back to mid.
• The flash count for a level may be decremented by holding the R/C channel 4 control low while operating the R/C channel 3 control; R/C channel 4 is available on some Micron transmitters - e.g. F2 on Tx20v2 and S2 on Tx22X and Tx42v2
• The level value is accepted and the flash count for the next level is displayed by setting the R/C channel 3 control high and back to mid.

Most Micron transmitters have a toggle switch on R/C channel 3 which is marked A/B, or forward/reverse for a low-off transmitter:

• pushing the switch down (or toward 'reverse' for a low-off transmitter) sets the R/C channel to a low value and increments the flash count,
• pushing the switch up (or toward 'forward') sets the R/C channel to a high value, accepts the flash count and moves the program sequence on to next level or exits programming mode if the current level is the last in the sequence.

The receiver LED will flash rapidly while R/C channel 3 is high or low and then return to a slower repeated flash when the control is back to the middle.

After accepting the flash count for a level, the receiver LED displays a flash count for the current value of the next level. This could be higher than 1-flash if the function is set in the receiver configuration or has been previously programmed. For example:

• the default Selecta R/C channel is 2, so a 2-flash will be displayed after entering 4,8,2
• P1 is configured as a front light, so a 4-flash will be displayed after entering 3,1

When the last level for a sequence has been accepted, the receiver LED will light continously and the receiver is back in normal operating mode. The maximum number of levels is 5, but not all sequences use all 5; if level 5 in the table is blank, the CPU LED will light continously after level 4 is accepted.

Programming changes are accepted only when the receiver LED lights solid at the end of the sequence. If a mistake is made mid way through a sequence, switch the receiver off to abort.