I2C Control for Hitechnic Motor Controller

Hi everyone,

While waiting for our FIRST Tech Challenge electronics to arrive (I am at an international school in China), I decided to look into using an EV3 as an interim robot controller for doing some testing. We have a Hitechnic motor controller connected to port 1 of the EV3. I saw in the Hitechnic controller documentation that bytes at 0x45 and 0x44 are for the motor 1 power and mode. I figured it would be an easy task to send an I2C signal using the motor block. I’ve attached an image of the simple program I created and the Hitechnic manual.

I’ve tried a number of different permutations of sending bytes to the two addresses, but nothing has resulted in anything coming out of the controller. I’ve also tried reading bytes that should be static values sent by the controller, but I don’t get anything logical back. I’ve also tried the decimal equivalents to 00x44 and 0x45 (68 and 69) but the same null behavior occurs. I also tried sending the value of 100 to every address from 0 to over 1000, and still nothing. The manual says that the controller is expecting a power value from -100 to 100, but the EV3 block is limited to positive integers only. I’m not sure if it’s possible to send a byte through this block.

Any ideas? I know there’s something simple I’m missing. Several students looking to test out some designs will be grinning ear-to-ear if you can give us a hand.

Thanks for the help!