DC Motor RF Interference

I wrote a P1 driver for 433Mhz modules that is pretty stable when I run it with no load on the serial terminal. In the screenshot "253" is the number I assigned to the drive wheels. (I want to add a panning camera and I'll assign "252" to it.)
The two values below '253' control forward or reverse speed .

When I connect a geared DC motor the motor glitches badly. I connected a DC motor to 4V, no PWM, no diode, and connected an oscilloscope probe to the motor terminals. The 'Measure' menu shows a maximum voltage spike of 15.6V.
I'm guessing the the voltage spikes are caused by the brushes bouncing on the commutator producing RF interference. Part of the problem could be that I'm using two 'QuickStart' boards and there is not enough USB current to prevent a reset.
A diode would control the reverse spikes but it looks like I would still need capacitors to filter out the positive spikes.
I ordered some 0.1uf capacitors and I'll run some low voltage tests before I connect a Propeller. I would appreciate it if someone could offer some some advice.


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