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Basic questions on USB (MC9S08JM)

Question asked by SP Lee on Dec 27, 2010
Latest reply on Jan 7, 2011 by Tsuneo Chinzei

I am learning the implementation of USB on MC9S08JM. I have a few questions:


- What is meant by a USB transaction? For example in a Control Transfer, does it mean the completion of each phase (Setup phase, Data phase, Handshake phase), or the completion of all 3 phases?


- The TOKDNE interrupt is triggered after each phase, or after the 3 phases has completed?


- If TOKDNE interrupt is triggered after each phase - that means for the entire Control Transfer, 3 interrupts will be triggered. How does the CPU handle each interrupt?