[En-Nut-Discussion] SPIBUS and PullUp and testing Miso line.

Uwe Bonnes bon at elektron.ikp.physik.tu-darmstadt.de
Thu Aug 28 14:52:18 CEST 2014

>>>>> "Ole" == Ole Reinhardt <ole.reinhardt at embedded-it.de> writes:

    Ole> Hi Uwe, Am 26.08.2014 16:55, schrieb Uwe Bonnes:
    >> to see if the ADC is ready, for SPI Sigma Delta ADC from Linear
    >> Technology like the LTC2484, one has to select the device, apply a
    >> pullup to SDI and query the SDI pin without toggling SCK. Only if SDI
    >> is low, data is available.  - Is it OK to add SPI_MODE_PULLUP
    >> properity in include/dev/spibus.h?  - Is it worth to add a method to
    >> query the Miso pin?  I would implement handling of those mode bits
    >> and function in STM32 and GPIO. However I can also circumvent the
    >> driver and use GPIO Functions directly...

    Ole> I never heard of such a requirement, but do you have a clue, if
    Ole> this is a standard?

Standard asr fine, so everybody has it's own standards. But at least the
Analog devices AD7982 in "CS MODE, 3-WIRE WITH BUSY INDICATOR" has also SDO
floating while busy and pulled low when ready.

    Ole> In this case we should add it to the driver, but I assume it is a
    Ole> very special case for these ADCs, so a solution implemented with
    Ole> the GPIO functions would be better in my eyes.

Probably it's not worth to abstract those things...

Uwe Bonnes                bon at elektron.ikp.physik.tu-darmstadt.de

Institut fuer Kernphysik  Schlossgartenstrasse 9  64289 Darmstadt
--------- Tel. 06151 162516 -------- Fax. 06151 164321 ----------

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