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SPWF04S SPI basics problem

Question asked by bernd schönlebe on Jul 24, 2017
Latest reply on Feb 7, 2018 by Rakshith KR

Hi there,

 

I have alot of problems with SPWF04S and its SPI interface. From the datasheet this is what should happen:

TX:
1. The communication starts with the host sending the write SYNC word (0x02),
2. followed by header information, and then payload, when applicable.
3. Once the command has been analyzed by the device, it asserts the IRQ interrupt line.

 

RX:
1. Then the host detects the interrupts and then
2. writes the read SYNC word (0x02) and
3. starts to generate the clock.
4. The device then clears the interrupt line and prepares the response.
5. The host then reads continuously until the SYNC pattern is detected.
6. All data until that point is discarded.
7. The SYNC word is then followed by headers and then payload, when applicable.

 

for a start, as im not sure which diagrams are correct and which are not, im not sure what the default state of the module is. is irq default low or high? do I need to receive a message already?

If I attach it to my arduino uno and hook it up to the oscilloscope I can see that the IRQ line is initially LOW. so I do as stated and start with sending my test packet {0x02, 0x00, 0x02, 0x01, 0x00} ("AT" alone) and wait for the IRQ line to go back up. This never happens! No matter if I keep CS low while waiting or not.

 

So can someone PLEASE give me a list of steps how the communication SHOULD work? Btw, I have no interrupt on that pin, so I can only check it from time to time

 

Best regards

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