Can I set MOSI default HIGH, and set CS low separately for ~1ms? about py-spidev HOT 6 OPEN

Hi,
Did you arrive at any conclusion about this?

Thank you very much,
Sofia

from py-spidev.

I'm having similar issues. Any solution?

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You may be able to get the same effect as MOSI default HIGH (also called "active low") by inverting the data you're sending (i.e. flipping each bit before transmission, e.g. converting 0b00110011 to 0b11001100). You can do this easily; if foo is a byte of data, instead of spi.xfer(foo) you'd spi.xfer(~foo).

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As far as setting the CS pin to wake up the chip, will it work if you just send a byte (or a few bytes) of non-data (e.g. 0x00 or 0xFF etc.) first? My cursory inspection of the datasheet implies that for the LTC6804, that should work, although I haven't taken the time to fully understand the function of the device.

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I believe the OP described the situation well.
I have Arduino witch is generating same SPI command, but data line rests HIGH, but is not inverted. CS will wake the device.
Raspberry sends same command, but MOSI is resting in LOW state and cannot get chip to wake up.

Problem here is that this is not direct SPI connection, but trough LTC6820 isoSPI bus converter.
RaspBerry <-- SPI --> LTC6820 <-- isoSPI --> LTC6804

Next step is to add OR gate in MOSI line that another GPIO line can force MOSI up during WAKEUP sequence

from py-spidev.

I can confirm that I got this working with help of additional IO line witch will force MOSI line rest to HIGH. Simple solution with 2 shotky diodes was enough to achieve this.

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