I want to know how to use the IFB pin in the TFC-shield.

[jeonghwanchoi]

hello

I am trying to control the DC motor through the TFC-shield.

In the TFC-shield, there is a IFB pin (as I know, This pin represent the armature current  over 375 . am I right?)

Here is my questions,

1. Can I  PID control the DC motor with just known about armature current?  I have to measure the angular velocity of the tire as far as I know .

     because armature current and angular velocity are not simply related. so In my opinion It is hard to control the DC motor using armature current .

2.  If I can, then how to use this..?

thanks.

[bobapplonie · Accepted solution]

I believe that is a current feedback pin. According to the datasheet: "The load current feedback output provides ground referenced 0.24% of the high side output current. (Tie to GND through a resistor if not used.)"

You could measure the current through each motor with this pin, but I don't think that is very useful in controlling the motor--a speed sensor on the wheels is probably more useful. The schematics for the board are here: https://community.freescale.com/servlet/JiveServlet/download/93914-26-257650/FRDM-TFC-REVB-BUILD_PAC...

From that, you will see that you enable the H-bridge thru H-Bridge-Enable connected to PTE21 and control the speeds of each motor by applying PWM to H-Bridge-A-IN1/2 (PTC3 and PTC4) and H-Bridge-B-IN1/2 (PTC1 and PTC2).

Good Luck!

Bob

[FlavioStiffan]

GregoryCAMUZAT​ johnmc(test) any idea about this?