Do SPI pins need pull-up/pull-down resistors?

afromero · September 2, 2014, 1:58pm

The core set this inboard or do I need to set a pull-up/pull-down resistor? Very thankful.

kennethlimcp · September 2, 2014, 2:27pm

I believe it’s done with the internal resistors and the user is not required to add it externally.

At least that’s what i have been doing with my SPI devices…

Digging into the core-firmware reveals it as well:

particle-iot/firmware/blob/9b01d795ecaaf657399dc4888f30f3898d91d74a/src/spark_wiring_spi.cpp

/**
 ******************************************************************************
 * @file    spark_wiring_spi.cpp
 * @author  Satish Nair
 * @version V1.0.0
 * @date    13-March-2013
 * @brief   Wrapper for wiring SPI module
 ******************************************************************************
  Copyright (c) 2013 Spark Labs, Inc.  All rights reserved.
  Copyright (c) 2010 by Cristian Maglie <c.maglie@bug.st>

  This library is free software; you can redistribute it and/or
  modify it under the terms of the GNU Lesser General Public
  License as published by the Free Software Foundation, either
  version 3 of the License, or (at your option) any later version.

  This library is distributed in the hope that it will be useful,
  but WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  Lesser General Public License for more details.

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peekay123 · September 2, 2014, 2:58pm

@afromero, I agree with @kennethlimcp that no pull-ups are necessary for the SPI bus.