SPI Pulldown Resistors Purpose

[TrisM]

Hi,

An educational query for myself, looking at the schematic, there are pulldown resistors on the SPI lines, but literature I have read insists that there is no requirement for pull-down/pull-up resistors on SPI lines. Only info I could find is regards mostly using pull-up for certain scenarios.

Thank you

[Christian_Bylund]

Hi,

An educational query for myself, looking at the schematic, there are pulldown resistors on the SPI lines, but literature I have read insists that there is no requirement for pull-down/pull-up resistors on SPI lines. Only info I could find is regards mostly using pull-up for certain scenarios.

Thank you

Hello, without saying it is right or wrong.

Why pull-down or pull-up resistors? - To avoid floating pins before they are configured.

Why pull-down instead of pull-up resistors? - To avoid 5V actively high pins from the shield.

[Roger74]

The pull down resistors given on the schematic is not what has been incorporated on the shield itself.
Interesting.
The 8101 incorporates pull up resistors on both the CS and Clock pins: