testing H-bridge

I am answering myself on this one, Its the Vdd from the motor that is turned on and Off from the enable, Thats is what changes the speed. k

What is connected to the two supply pins, 8 and 16?

Are you intending to run the motor either direction, by connecting it between 3 and 6?

With pin 7 grounded, you are telling the driver that, when enabled, it is to pull down on pin 6. And by connecting pin

I would select a direction for motor voltage by pulsing high (PWM) one of 2 and 7, while lowering the other, continuously. Enable would also be high, continuously. This causes the effective motor voltage to be approximately the supply times the duty cycle. If you want the motor to coast, lower the enable.

The PIC output may read 2.5 volts with a meter, but that is an average reading of a pulse that is 5 volts half the time, and zero volts the other half the time. It is never steady at 2.5 volts. The 293 does not respond to the average voltage from the PIC, but pulses its outputs in synchronism with it (if it can keep up).

I don't think you should be pulsing the enable pin to PWM the motor. This does not apply an effective voltage of the supply times the duty cycle (supply voltage during the on time, and zero volts during the off time, by shorting the motor), but much less. It pulses between supply voltage (minus losses) when on, and negative supply voltage plus diode drops when off, as the motor inductance reverses the voltage to try to keep the current going through the clamp diodes. At 50% duty cycle, the current runs down to zero before the off time is over, so the average voltage is approximately zero.