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SPI Transfer
March 27, 2017
11:23 am
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undermeadow
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March 24, 2017
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Am I doing something wrong or is the SPI function poorly implemented? Even if I set the Transfer Mode to Continue there is still huge 5ms delay between transferred bytes. How can I get rid of it?
And what about Data Command? How can I set whenever the transferred data are data or command. I can see that everything is sent as Command automatically.
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April 3, 2017
1:46 pm
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ddowning1327
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Are you watching the output with an oscilloscope?  Could you attach a screenshot? Which arduino are you using?  I used a Due and i only had 1us between bytes.

April 3, 2017
2:28 pm
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Steffan
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undermeadow said
Am I doing something wrong or is the SPI function poorly implemented? Even if I set the Transfer Mode to Continue there is still huge 5ms delay between transferred bytes. How can I get rid of it?
And what about Data Command? How can I set whenever the transferred data are data or command. I can see that everything is sent as Command automatically.

Yes, unfortunately for AVR boards (non Due), there is an intentional delay added between CS low and start of transfer.  This is because the AVR boards to not handle CS in hardware and it has to be handled in software using a GPIO output.  There has to be some delay between CS low and transfer for slave devices.  If you use a Due, the CS is handled by the SPI peripheral so that delay should be smaller.  To control that delay on AVR boards, you could wrap a custom library to achieve what you want.

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