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JWiec
JWiec
Associate
March 10, 2019
Question

STM32F4 DCMI - difference between IT_FRAME vs IT_VSYNC interrupt

  • March 10, 2019
  • 2 replies
  • 1095 views

I'm trying to get OV5642 Arducam camera module to send data to STM32F429 (Discovery DISC1 board), I am using hardware synchronization. Could you tell me what is the difference between two DCMI interrupts: IT_FRAME and IT_VSYNC? I had trouble understanding this from reference manual:

"IT_FRAME - Indicates the end of frame capture, IT_VSYNC - Indicates the synchronization frame".

What is synchronization frame, is it connected somehow with embedded synchronization? What does this interrupt mean if I'm using hardware synchronization?

Knowing that these two interrupts probably appear after every frame I was expecting to see same amount of them. In fact, IT_VSYNC shows much more often than IT_FRAME. Additionally, amount of IT_VSYNC interrupts seems to be reasonable, compared to IT_LINE interrupts it is consistent with expected image vertical size. But why IT_FRAME interrupt is not shown after every IT_VSYNC interrupt?

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2 replies

waclawek.jan
waclawek.jan
Super User
March 10, 2019

I am not a DCMI expert, but from reading the RM, VSYNC interrupt occurs always upon VSYNC changing from inactive to active, regardless of whether there's a capture ongoing or not - FRAME interrupt occurs only when capture achieves end of frame, either indicated by VSYNC or before that if crop is set, but certainly only if capture is going on.

JW

JWiec
JWiecAuthor
Associate
April 6, 2019

Thanks!

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