Pan tilt hat (w/ servo) question


#1

using RPi 2B

when HAT is on top of RPi (pin-to-pin)…servos work fine

however I need to use external 5V source to power both servos

so…I tried to run jumper wires between pins 27/28 on RPi (SMBus 1) to 27/28 on HAT
& 4/6 (5V/gnd) on RPi to 4/6 on HAT

RPi does not show device (ie i2cdetect) and (of course) servos do not activate

what am I missing…I assume HAT should work without being on top of RPi!!

any help is greatly appreciated


#2

The pins used for Pan-Tilt HAT are 2 and 3 (SDA/SCL), as you’ll see at the pinout link below.


#3

You don’t need to take the HAT off necessarily. You can just jumper the servo data pin over from PanTilt HAT to the servo connector and feed 5v into the servo connector directly from your power source. Make sure to tie the ground of your power supply though.


#4

thanks.
re: You can just jumper the servo data pin over from PanTilt HAT to the servo connector
I am having trouble picturing this
the servo connector has 3 connections…so I am having trouble picturing what you are suggesting…unless I chop off the connector and connect each of the 3 wires separate to accomplish what you are saying

if you could possibly sketch your scenario…it would help me!
thanks


#5

You can just push wires into the connections on the servo connector. So grab some male-to-female jumper jerky, connect it to the data pin on each of the PanTilt HATs servo headers, and then into the corresponding data pin hole on the connector of each servo.

The connector will then have the power/ground connections free, you can feed a 5v supply directly into these and make sure to also connect the ground of this 5v supply back to PanTilt HAT so you have one common ground reference across your circuit.

If you’re okay with soldering, you could grab a perf board and connect some 3-pin strip header to it to make some more permanent connections.


#6

This might help!