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PaxInstruments / labwiz-board

A development board based on the STM32 series processors specifically targeting the STM32F103RxT series.
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SPI pullup/pulldown resistors #125

Open charlespax opened 7 years ago

charlespax commented 7 years ago

Do we need any pullup or pulldown resistors on the SPI lines?

electrokean commented 7 years ago

Generally I'd put a pullup on the SPI_NSS (!CS) signal at the slave. I may also put a pullup on the MISO at the master, but this can usually be done via the internal I/O pin configuration. An external (lower value) may be needed if there are long connecting cables. A reference to Arduino SPI best practices: https://www.dorkbotpdx.org/blog/paul/better_spi_bus_design_in_3_steps

charlespax commented 7 years ago

In the STM32 datasheet and reference manual I cannot find anything indicating that SPI has any pullup resistors. However, GPIO does. I'm not sure if that also translates to that pin in SPI mode. I'll just keep them for now.

I'm putting this in the ice box for future investigation.

charlespax commented 7 years ago

I'm putting pullups on the board. We can try them. screen shot 2017-01-27 at 17 28 24

charlespax commented 7 years ago

Moved to Milestone 4.1 for review after we have the 0.4 boards.