Every one of Marty's motors is a Smart Servo, which provides feedback about its position and the electrical current flowing through it. A motor generally draws more current when it works harder, so the current reading gives an indication of the load on a joint. It is not a direct measurement of force.

===== In Blocks =====

  - Open [[https://robotical.app/blocks|Blocks]] and connect to Marty.
  - Select your Marty device, open **Code**, and choose **Sensing**.
  - Find **Current at [joint] joint (in mA)** and select a joint from its dropdown. The example below uses **right arm**.
  - Tick the checkbox beside the block to display its current reading in milliamps (mA).

{{ :martyv2:userguides:sensorsandaddons:motor-current-block-2026.jpg?nolink&600 |Current at right arm selected in Sensing, with the current monitor displayed}}

Try asking Marty to move and watch how the reading changes. Make sure the joint selected in the Current block is the one you want to monitor.

==== Reacting to force ====

We can use motor current to make Marty react to a change in load. This example raises Marty's **right arm**, holds it in position, and then dances when the current rises above a threshold as you gently press the arm:

{{ :martyv2:userguides:sensorsandaddons:motor-current-force-example-2026.jpg?nolink&600 |Program to raise the right arm and dance when the right arm motor current exceeds 50 mA}}

  - Move the **right arm** to **90 degrees** in **1 second**.
  - Wait **0.5 seconds** for the movement to settle.
  - Repeat **Hold this position for 0.5 s** until **Current at right arm joint (in mA) > 50**.
  - Run **Dance!** when the condition becomes true.

Use **right arm** in both the Move and Current blocks. **50 mA is an example threshold**: watch the current while the arm is holding still, then choose a value above that normal reading. If Marty dances immediately or does not respond to a gentle press, adjust the threshold.

The **Hold this position** block matters because Marty is normally poseable when not moving. Without it, Marty may simply let you move the arm instead of resisting and drawing more current.