Motor driver problem w/ HPWM

[Amoque]

I am using a 16F88 and HPWM, but this isn’t a PBP question, so I suppose I cannot be too far wrong in posting here? If I am wrong, someone will say where is better?

I am using an SN754410 (4x Half-H driver) to control one motor, so 2/4 of chip to one motor lead, 2/4 to other. I have used this chip successfully many times; I know it is wired correctly in this regard.

The difficulty is that I have not ever used PWM on enable pins… and my current difficulty makes me wonder if it is correct to short 1 and 9 (enable pins) and tie to HPWM signal for speed control. The ‘scope shows very nice square wave from PIC to enable, but 12V output from chip is not so nice and VOM shows no less than ~10V during a complete 0-255-0 sweep of HPWM signal. ‘scope of output signal is not square either—I am at a loss to describe the shape of it, but something like the tail from a ‘q’ shaped like ¼ sine wave hanging from the signal high.

I read that using an inverter chip (Xor, I think?) could be used, but I did not understand fully and it seemed that perhaps this was for generating power while the motor coasts—not a concern for me. I only need to ramp up, control speed, and brake.

Anyone use this chip with PWM and can offer some advice to a knoob?

[Amoque]

For those staying awake nights trying to figure this out () and to complete the thread-- bad soldier joint causing one of the half-drivers not to come on. Fixed...

[mackrackit]

Wheww, now I ca zzzzzzzzzzzzzzzzzzzzz