SPI-communication problems

Go To Last Post
2 posts / 0 new
Author
Message
#1
  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Hi,
I'm having problem with the SPI-communication. The syncronisation between the two uC:s appers
to be corrupt after startup. The slave does not send anything to the master.
But when I put the probe from the oscilloscope on the clock pin
everything works, and the SPI exchange data.

How do I change the clockpulse when put the probe on the clock pin?
Should the clock pin be loaded in some way for proper function?

Sicerely,

/ Michael

admin's test signature
 

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Hi Michael,

How have you set up the read/write cycle of your master and slave? The normal set-up is to let Write happen on the rising edge of the clock, and reading on the falling. If you've set both up to execute at rising edge, for instance, the communication would be corrupt. It is possible that the capacitive load of the probe might barely provide the delay necessary for the Slave to be able to read on the same edge on which the Master has written.

This is a long shot, but... :)

Best regards,

Morten, AVR tech. support, Atmel FAE

admin's test signature