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Micron MR001a 2.4GHz DSM2/DSMX Receiver
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The MR001a receiver is well suited for use in large scale live-steam or battery powered locos. It operates on 2.4GHz using the Spektrum DSM2 or DSMX protocols; thus it operates just like any other DSM2/DSMX receiver but includes some useful features for model railway control. The MR001a is small (30x18x11mm) and space for it is easily found in most locos.
The MR001 family of receivers includes two hardware variants:
The MR001a free-air range, when used with a Micron low-power transmitter, is 40m-50m and approximately 200m when used with a full-power (100mW) transmitter. This range will be reduced indoors due to absorption by furniture / fittings and reflections from metal surfaces. Range is also reduced if the receiver aerial is in a metal enclosure. Ideally, the aerial should be placed outside the vehicle body and clear of any metal. The active tip of the extended aerial needs to 'see' the transmitter so should be placed through a hole in the loco body - e.g. into the cab space. The MR001a aerial should not be cut short or made longer as this will affect operation of the receiver. It is important to perform a range check after installation to ensure you have full control of your loco at all positions around the layout.
Features (top)
Connections and Indicators
MR001a has 7 sets of output pins which can be used for servos or LEDs for lighting. The pin sets, numbered from the top of the diagram below, are 0.1" pitch to take standard R/C plugs. An additional 8th output for LED or sound card trigger is available via a JST-ZH socket at the rear of the receiver - this output cannot be used for connecting a servo as the positive pin is powered from the on-board 3.3V regulator which has insufficient current capacity for a servo.
MR001a can be powered from a battery of 3.45V up to 8V; use of a 4 or 5 cell NiMH rechargeable battery or the 5V regulated output from a speed controller is typical.
The standard configuration has servo outputs on P1 to P5, front/rear lighting on P6 and P7 and a channel 3 switched output on P8:
MR001a has 2 LED indicators, one on the top near the aerials and another on the bottom, these are labeled 'LED RF' and 'LED CPU' on the diagram below. There are actually 2 LEDs on the bottom, but only one of them is used.
Live Steam
For live-steam use, the MR001a outputs can be connected to standard R/C servos to operate the regulator, reverser, blower, gas valve and whistle. MR001a will work with any servo that uses a standard (1ms - 2ms) pulse width control signal and operates off the selected battery voltage - e.g. Blue Arrow 3gm.
When used with a Micron model rail transmitter, throttle is on P1/ch1 controlled using the large speed knob and direction is on P3/ch3 controlled using the toggle switch. The Micron transmitter should ideally be configured for low-off throttle with no centre detent and a non-biased direction toggle switch. When used with an aeromodel type stick transmitter, throttle is controlled using the throttle stick and direction is controlled by the elevator stick. Servos, plugged into MR001a P1 and P3, are linked to the regulator and reverser. The battery can be connected, via an on/off switch, into any of the unused pins.
Battery Powered Loco
An Electronic Speed Controller (ESC) that supports forward and reverse should be connected to P1/ch1 as shown in the diagram. The MR001a is powered from the ESC 5V output.
The resettable fuse is essential to protect the battery in the event of a ESC or wiring fault. The switch must be capable of carrying the maximum motor current; if a suitable mechanical switch cannot be found, an electronic switch should be used instead (contact Micron for details).
Any of the Micron model rail transmitters can be used or a Spektrum compatible stick type transmitter. Tx21 and Tx22 transmitters have an inertia control which gives a more realistic acceleration and deceleration by slowing down the rate at which the throttle channel is changed.
Binding (top)
MR001a must be bound to a transmitter before use. Once bound, MR001a remembers the transmitter identity and searches for this when it is switched on. When binding, we recommend that servo rods are disconnected in case they are incorrectly set. Battery powered locos should have the motor unplugged in case the throttle is not set correctly or the ESC not calibrated for the throttle off position.
To bind a receiver, it is switched on with no transmitter active (for normal operation, the transmitter should be switched on before the receiver).
Some variants of MR001a support autobind where the receiver automatically goes into bind mode approx 5 seconds after switching on with no pre-bound transmitter active. If autobind is available, this will be indicated on the receiver label. All variants support manual binding.
Bind mode is indicated by a rapid flashing of the receiver RF LED and the following steps should be followed to bind with your transmitter:
Loco Selection (top)
Tx22, Tx24 and Tx72 have a 12 way switch to allow control of up to 12 locos - Deltang call this feature 'Selecta'. Using the switch, locos are brought under control one at a time. When not selected, MR001a outputs hold their current setting (e.g. a loco which is moving when deselected keeps moving) and the CPU LED shows a 2-flash pattern.
The implementation of Loco Selection in MR001a is fully compatible with the Deltang Selecta feature and uses R/C channel 2 by default. When Loco Selection is enabled, the controlling R/C channel (e.g. 2) may still be mapped to a servo output but, of course, this will not change as the transmitter switch is rotated.
The receiver has a 800ms delay before enabling when the transmitter Selecta value is changed. This is to avoid obeying the transmitter while the Selecta switch is being moved - e.g. a receiver on Selecta #4 should not change any outputs while the transmitter Selecta switch is moved from #3 to #5.
MR001a is normally supplied with Loco Selection disabled. To toggle whether Loco Selection is enabled or disabled:
Loco Selection may also be enabled by programming.
Directional Lighting (top)
Pins P6 and P7 can be used to drive front and rear LED lights; P6 powers a forward LED and P7 a backward facing LED. The directional lighting pins can be changed by programming the receiver.
MR001a has an on-board 3.3V regulator and 220 ohm resistors in series with the signal pins so limits the LED current to approximately 12mA. The LED should be connected between the signal and negative pins (top and bottom rows).
The default setting is for the LEDs to follow the throttle channel with 'centre-off' and is appropriate for a battery loco with ESC. For live-steam use, the LED behaviour can be reprogrammed for 'low-off' and this uses full-range throttle on ch1 and directional control on ch3.
To toggle whether the directional LEDs operate as 'centre-off' or 'low-off':
Jumper Changes (top)
This is a summary of the configuration changes that can be made using a black jumper across the signal pins:
Receiver Programming (top)
The type of output for each MR001a pin can be changed using a bound transmitter. MR001a must first be put into programming mode and then the direction toggle switch, or elevator on a stick type transmitter, is used to enter a program sequence one digit at a time. The CPU 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.
The programming table below lists all of the functions that may be changed by programming the receiver. The table is split into 3 blocks of related functions each with the same value in the first column: 1 = core receiver functions, 2 = servo functions and 3 = general on/off functions.
The table columns contain the program values which must be entered to change a particular function. For example, to set Loco Selection on using R/C channel 2, the program sequence 1, 2, 2, 2 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:
There are 2 methods of getting the MR001a into programming mode:
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.
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 below. 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.
Most Micron transmitters have a toggle switch on R/C channel 3:
The receiver LED will flash rapidly while channel 3 is high or low and then return to a slower repeated flash when channel 3 is back to the middle.
After accepting the flash count for a level, the CPU 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:
When the last level for a sequence has been accepted, the CPU 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 CPU 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.
These examples assume MR001a is in as-received configuration and a Micron transmitter with toggle switch on channel 3. Tx24 transmitters have a variable control on channel 3 - the Reverser; the equivalent actions are:
Servo Throw Adjustment (top)
Servo throws (low and high end points) can be configured using a bound transmitter, the servo centre position will always be at the mid-point of the low and high travel. To adjust a servo, the servo output is selected first and then the travel adjusted using either the throttle control or direction toggle if the throttle servo is being adjusted.
The steps below assume a Micron transmitter is being used. If the transmitter is an aeroplane type stick transmitter then the elevator stick corresponds to the direction toggle.
Only one servo output can be changed at a time. Go through the above steps to adjust a different servo output pin.
