Teensy 3.6 cant take enable of L6234 high

[owhite]

Hey Folks,

I designed a PCB for a brushless motor driver. The picture shows a subset of the total circuit. The issue is I'm using L6234 motor drivers to run the BLDCs, and I tied all of their enable pins to one pin on a teensy 3.6. I figured if the teensy can drive 30mA on each pin it would be okay. For some reason the lil guy cant pull up all the enables on the four L6234s. The spec sheet says that IENH, "Input HIGH current on enable", is 30uA. Seems to me that pulling up 3 pins on the four chips should be fine. Other items:

• The attached circuit [LINK] shows the network in the circuit M_EN highlighted in magenta.
• At present, the firmware on the teensy is only driving the M_EN pin, so there should not be additional current draw on other pins.
• My oscilloscope reports 0V on pin 37.
• I loaded the same firmware on another bare teensy and pin 37 goes to high.
• Tying the enable pin on my PCB to 3.3v (which I think I shouldnt have done without a resistor) takes the teensy pin to high.

Code is:

void setup() {
  pinMode(37, OUTPUT);
  // tried with and without next line
  pinMode(37, INPUT_PULLUP);
}
void loop() {
  digitalWrite(37, HIGH);// enable 
}

Where did I go wrong?

thanks.

 

[PaulS]

Hi,
Perhaps there is something wrong with the PCB (or soldering)?
Is it possible to isolate the T3.6 pin37 from the PCB such that you can measure pin37 itsself for correct level with the above code?
If that works then there may be a low resistance path from the L6234 EN pins to ground.
If you pullup the M_EN line with 3V3 [without T3.6 connected], what current is drawn from your 3V3 powersupply?

Regards,
Paul

 

[owhite]

I apologize it appears that there was something sporadic with the PCB. Sorry to take your time, and thanks for your help.

thx

 

[PaulS]

No problem, glad it works!
Paul