Bug #276

Sensors are 5v logic feeding into 3.3v inputs on the controller

Added by J. Simmons over 5 years ago. Updated about 5 years ago.

Status:Resolved Start date:02/06/2017
Priority:Normal Due date:
Assignee:Bryan Christian % Done:


Target version:-


We have somehow managed to get away feeding the 5v logic from the Hall Effect sensors into our 3.3v logic controllers (both the v0.3 controller and the in development v0.4 controller). We need to step the 5v logic down to 3.3v logic for the final design in v0.4.

SparkFunLogicLevelConverter.jpg (311.6 kB) J. Simmons, 03/10/2017 01:20 pm


Updated by J. Simmons over 5 years ago

  • Assignee set to Bryan Christian

Bryan has researched this issue and has a proposed solution (originally posted on Discord):

SparkFun Logic Level Converter - Bi-Directional

Sparkfun's bidirectional logic level converter for stepping up/down, connect your 5V side to high, your 3V side to low. 2.95 per unit, plus they have the circuit schematic available and it's only a very small total cost in components.

  • <0.21 per unit on the MOSFET and a pair of resistors
  • each stepper is 1 BSS138 MOSFET from Fairchild and two 10k resistors

PBI DEV-03 covers addressing this issue. Assigning to Bryan since he has done the research.

Updated by J. Simmons over 5 years ago

Bryan has ordered and received the logic level converter from SparkFun (shown below next to a CHIP Pro dev board for scale). Next up is to test out that it works with Holoseat.

Updated by Bryan Christian about 5 years ago

Was able to confirm proper voltage drop using the board. We do need to provide both 5V and 3.3V to the board, which I did not do during the test. VBUS to HV on the Sparkfun board, VCC3.3 to LV on board. Sensors go on the 5V side, 3.3V for the board side. The ground is routed through the ground pins on the matching side.

Updated by J. Simmons about 5 years ago

  • Status changed from New to Resolved

Also available in: Atom PDF